How to determine gold purity at home
Gold is one of the most popular precious metals these days, which is widely used in jewelry production. High-quality gold jewelry is very valuable, so counterfeits of gold jewelry are increasingly appearing on the domestic and foreign markets. In this regard, it is very important to know how to determine the gold standard, and in some situations, how to test the gold standard at home.
Testing system in Russia
Precious metals assay system
The most important confirmation of the authenticity of gold jewelry is the sample. Assays are mandatory on all jewelry made of precious metals that go on sale.
The Russian assay system provides for the following gold samples:
The digital sample value corresponds to the content of pure precious metal in one kilogram of jewelry, presented in grams.
The Russian testing system is called metric. Along with it, there are also spool and carat testing systems. The correspondence of samples for each of these systems is as follows:
- 375 standard in the metric system corresponds to 36 standard - in the spool system, which is equal to 9 carats;
- 500 standard in the metric system corresponds to 48 standard - in the spool system, which is equal to 12 carats;
- 585 standard in the metric system corresponds to 56 standard - in the spool system, which is equal to 14 carats;
- 750 standard in the metric system corresponds to 72 standard - in the spool system, which is equal to 18 carats;
- 958 standard in the metric system corresponds to 92 standard - in the spool system, which is equal to 23 carats;
- 999 standard in the metric system corresponds to 96 standard in the spool system, which is equal to 24 carats.
However, the presence of a hallmark on a piece of jewelry, unfortunately, in our time does not guarantee its authenticity. Of course, the right action when choosing gold jewelry would be to go to a specialized store or salon.
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Usually, to determine the gold purity of a particular piece of jewelry, it is necessary to contact specialized government inspections, whose employees will conduct appropriate chemical experiments to help determine the gold purity in the jewelry.
However, it is not always possible to turn to professionals for help, and the need arises to independently establish the authenticity of gold jewelry.
You can determine the gold standard yourself at home using:
- magnet;
- iodine and vinegar;
- of bread;
- similar item;
- touchstone;
- reagents.
Next we will talk about each of the mentioned methods separately.
Magnet check
Magnet
Verifying the authenticity of gold jewelry with a magnet involves simple manipulations that involve bringing a magnet to the item and determining whether it is magnetized or not.
Products made from genuine gold, as well as jewelry that contains a minimal amount of impurities, should not be magnetized.
If the product sticks to the magnet, it means that its composition is dominated by foreign impurities.
Checking with iodine and vinegar
Gold ring after testing with vinegar
Exposure to iodine or vinegar should not in any way affect the structure or appearance of gold jewelry.
If a drop of one of these solutions provokes the formation of darkening, it means that you are not holding a genuine gold product in your hands or its content is not high.
It is important! If the standard of your jewelry is 585 or lower, we do not recommend testing with iodine; stains may remain, which will then need to be removed with ammonia.
Bread test
This is perhaps the longest way to check gold jewelry for authenticity.
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To conduct this experiment, you need to take a piece of fresh Borodino bread, after kneading it, put a piece of jewelry in it, and leave it in a cool and dark place for several days.
After this, you need to break the stale bread. If the product has acquired a green color, it means it is made of base metal, or with a large consistency of foreign impurities.
Similar subject
You can establish the authenticity of a piece of jewelry by comparing it with a product whose authenticity you have no doubt about.
To do this, you need to take two things (verifiable and genuine), and alternately draw lines with them on any solid object. If the clarity and color of the lines match, then both products are original, but if not, then one of the products is a fake.
touchstone
Touchstone
The most popular method of checking the purity of gold in jewelry is using a touchstone test. The versatility of this method lies, first of all, in the fact that in this way no harm is caused to the quality of the jewelry.
To conduct this experiment, you need to take a black block of siliceous slate, and draw a line on the surface of which with decoration. The set with siliceous slate always comes with a reference needle, which must be used to draw a line next to the one drawn by the jewelry.
If the two drawn lines are identical, then you have in your hands a piece of jewelry of 585 standard or higher. Otherwise, we recommend that you contact specialists for analysis, or resort to more serious methods yourself.
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Other verification methods
One of the alternative ways to more accurately determine the sample of yellow precious metal in jewelry is to check using a special device - the GXL-18 56.762X gold detector.
This device is a digital detector that, in a fairly short time (five to ten seconds), allows you to determine a quantitative indicator of the pure gold content in a product.
The device presents the results of the study in carats. The calculation is made based on the following ratio: 333-750 standard corresponds to 6-18 carats, respectively.
A characteristic feature of the detector is that it is able to distinguish true gold jewelry from gold-plated jewelry.
Typically, the detector is used in the jewelry industry to determine gold in various alloys with high accuracy. The sample determination process itself is based on an electrochemical reaction. It is often used in their activities by pawnshops, workshops and buying stores.
Another chemical way to test the sample of gold jewelry is acid reagents, which can be purchased in specialized stores.
Such reagents are produced in accordance with 375, 750 and 958 samples of gold. When the product is exposed to an acidic reagent, spots of a light brownish tint appear on the product. The intensity of the stain depends on the gold standard: the lower it is, the more intense the color of the stain.
A variety of ways to check the purity of gold in jewelry makes it quite easy to determine whether the gold product you purchased is genuine, and whether the hallmark marked on the product corresponds to reality.
Source: http://inzoloto.ru/precious-metalls/opredelyaem-probu-zolota-doma-iv-laboratorii
How to quickly and accurately determine the gold standard?
Always during times of economic instability, people preferred to keep their savings not in money, but in precious metals. And the most popular asset among them has always been and remains gold. Many people still buy gold items today. But can you always be sure that it is not a gold-plated fake? Or that there is no discrepancy between the specified and the real sample?
It is very important for all buyers to know how to determine the purity of gold. After all, it has long been no secret that gold products are almost never found in their pure form; various additives are always added to them: silver, copper, palladium, nickel, zinc. They do this both to diversify the color scheme and to make gold jewelry more durable.
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How to check gold for authenticity?
Before you bother with determining the purity of gold, it is worth spending a little time and checking whether the product being offered to you is actually gold, or if it is only gold plated. After all, there is no point in determining a sample of something you don’t have.
The simplest and most commonly used way to determine the authenticity of gold items is to hold a magnet to them. Real gold is almost not attracted to a magnet. If you see the opposite, then there is a high probability that this is a gold-plated fake, or, at best, jewelry made of gold of the lowest standard. It’s definitely not worth buying such a product for a lot of money.
You can determine the authenticity of gold at home using vinegar. Keep the product for some time (15 minutes) in a vinegar solution; if it is made of gold, no chemical reaction will occur, and the color of the product will remain the same. But a gold-plated fake will definitely darken.
The same can be determined using iodine. This method is especially good because it allows you to distinguish the most popular 585 samples from 583 or 750 with almost 100% accuracy.
To determine, you need to lightly scratch the surface with sandpaper in an inconspicuous place. Then you need to wipe this place with iodine and monitor the progress of the chemical reaction. If the product is 585, the treated surface will darken.
But this method has a weak point. If in this way you try to determine the gold standard of products made from alloys of copper, bronze, brass, and in appearance indistinguishable from gold, then nothing will work, since no dark spots will appear on their surface. Therefore, if they convince you that this product is made of 750-carat gold, and they test it with iodine to confirm it, then be careful and try to find out the gold purity using other methods.
Testing gold at home using iodine
Once you are convinced of the authenticity of the gold product, you can try to test it. Quite precise methods have been developed for this:
- drip method;
- electronic detector;
- assay needles or touchstone.
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Drip method
This method is based on changing the color of gold under the influence of a special chemical reagent. It is very easy to use and quick to get results, but to call it completely reliable would still be an exaggeration.
Having previously cleaned a small area of the surface with a needle file, a small drop of the reagent is applied to this area. After 15-20 seconds, the applied reagent is removed and the product is tested based on the change in color of the metal.
For products up to 600 fineness, gold chloride is used as such a reagent. On gold products of 583 or 585 purity, the trace of the chemical reaction will be light brown or orange-golden if the product is made of white gold. On 375 gold, the reagent will leave a green stain.
To determine 958, 750 and 375 samples using the drop method, acid reagents are also used (Image 1). The lower the sample, the darker the trace the reagent will leave on the gold.
The drip method largely depends on personal feelings and the state of the color memory of the assayer. It is difficult to use at home, since the necessary reagents are not at hand, and often the shades of color change are so similar that only a very experienced specialist can accurately determine the gold sample using this method.
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Electronic detector
A portable digital gold detector allows you to test gold products with high accuracy. The operating principle of this device is based on the electrochemical reaction of metals. It determines the pure gold content within 5 seconds.
It gives results in carats, the measurement range is from 6 to 18 carats, which corresponds to a range from 333 to 750 samples. This smart device also accurately determines the gold content in alloys and easily distinguishes gold products from gold-plated fakes.
Using a portable detector, you can quickly determine the value of jewelry
The price of such a device is quite reasonable, but buying it as a household appliance is still not economically feasible. But jewelry workshops, stores, purchases or pawn shops that respect themselves and their business probably have such devices.
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Assay needles or touchstone
Assay needles are special brass sticks, at the end of which thin multi-colored needles made of precious alloys are soldered. Each sample of gold has its own “own” color. The touchstone is a smooth, polished black block of siliceous, fine-grained slate. Its other names: “touchstone”, “black jasper”, “Lydian stone”.
A line is drawn along this bar with a gold product and, depending on its color, the gold standard is determined. But before testing the gold, the stone is first cleaned using charcoal and water. Then grease with almond or nut oil and wipe dry.
A touchstone is also used to test gold alloys for the ratio of gold and other metals in them. The check is carried out in the following way: in an inconspicuous place of the product, use a scraper or file to slightly scratch the surface to make sure that it is not a gold-plated product made of other metals.
This scratched area is then passed over the touchstone to create a small scratch on its surface. A drop of concentrated nitric acid is applied to this scratch for testing. 5 seconds after applying the acid, the sample can be determined by the reaction of the stone.
If the scratch has completely dissolved, then you most likely have low-grade silver in your hands; if you are very lucky, then maybe 333 gold.
If the scratch has changed its color to brown, then this is indisputable evidence of the presence of low-grade gold - from 375 to 500 samples. If the scratch has not changed color, it is indeed gold of at least 500 purity. And if the acid applied to the scratch boils, then this clearly indicates that the product contains no precious metals at all.
All developed methods for determining the purity of gold products are not very suitable for independent analysis. Therefore, when buying gold or silver jewelry, carefully examine the factory mark; fortunately, this does not require any instruments or reagents.
Do not hesitate to carefully examine the image in the presence of the seller. The mark must have a clear imprint and be placed at an equal distance from the edges of the product. The stamped hallmark numbers must be clearly embossed and of the same size. If the jewelry has a clearly marked brand of a well-known company, this is an additional guarantee of quality.
If, when examining the stamp, something alarms you, then it is better to refrain from such a purchase. And if you do decide to do it, be sure to keep the receipt and take care to carry out authentication with an organization that can issue an official document about its results.
Source: https://grammzolota.ru/proby/proverit-uznat-opredelit-domashnih-usloviyah.html
12 ways to check gold for authenticity
iPhones are iPhones, but there are also more eternal values. How to check whether they are offering you real gold or a cheap fake? You can’t drown him in royal vodka!
We tell you how to avoid being deceived when buying gold and how to check its authenticity.
1. Look at the sample
Factory products always have a standard stamp with a hallmark. Fineness is the number of grams of pure metal in the alloy; the lower it is, the worse the quality.
According to Decree of the Government of the Russian Federation dated May 6, 2016 No. 394, all alloys in which more than 30% of the weight is precious metal must be stamped with hallmark. Standard samples for gold are 375 (lowest), 500, 583, 585, 750, 916, 958, 999 (highest - only 1 g of impurities per 1 kg of metal).
In the USA and Canada, carat hallmarks are used (9 carats correspond to the 375th hallmark, 24 carats correspond to the 999th). Moreover, the letter K next to the numbers means that the product itself is gold, and KGP means that it is plated with gold (karat gold plated).
In Belgium, gold samples are designated by numbers: 1 – 833, 2 – 750, 3 – 585. A similar system works in the Czech Republic and Slovakia: 0 – 999, 1 – 986, 2 – 900, 3 – 750, 4 – 585.
Examining a sample is often difficult. Use your smartphone in macro mode, then enlarge the photo and look at the sample in detail. The mark should not be crooked or blurry. This is, if you like, a passport of the product, so they are very careful when applying it.
2. Smell the product
Gold items should not have a smell. Even silver has a characteristic metallic smell, but gold does not.
3. Take a closer look at the joints
On bracelets or chains, you can often notice a difference in color between the metal of the link itself and its joints. This is because when soldering gold, they use solder of a higher standard - it melts more easily.
If you see a difference in color, everything is OK, the gold is real. If not, you should carefully check the product in other ways.
4. Attach a magnet
Plating steel or other alloys with a high iron content with gold or its imitation is a common practice. Only ferromagnets are strongly magnetic - iron, cobalt, nickel, gadolinium, terbium, dysprosium, holmium, erbium, thulium.
Dimagnets (for example, water or table salt) and paramagnets (aluminum, etc.) are weakly magnetic. All non-ferrous metal is not magnetic.
If it happens on the beach or in places where tourists gather, buy the cheapest magnet in a souvenir shop and attach it to the product. If it sticks, it’s definitely a fake or the metal is of too low standard (too many iron impurities). If not, perform other checks.
5. Test with vinegar
Tell the seller that you will test the gold with vinegar. Are you nervous? There’s no need to run to the grocery store anymore. But a professional who is confident in his product will not sweat it.
Fake gold quickly darkens in vinegar - just pour a little into a glass and hold the metal in it for about five minutes. But real high-grade metal doesn’t care about anything.
6. Drop some iodine
Rub the product on jeans or other thick fabric, then drop iodine on this place on the metal. High standard gold does not darken. If the metal has darkened (this may appear within a minute), the product is not genuine or the standard is not too high.
But brass and copper do not change color from iodine either. So this testing method is good for high-grade gold, but it is not enough on its own.
We do not recommend testing products with iodine levels of 585 or lower. After iodine, you will definitely have to polish them or remove stains with ammonia; traces may remain.
7. Draw with lapis pencil
A lapis pencil is needed to stop the bleeding. This is an antiseptic based on silver nitrate, it can be bought at a pharmacy, it costs about 100-150 rubles.
To check the authenticity of gold, soak the item in water. Then, using a lapis pencil, draw a small line over the wet one and wipe it off.
Lapis does not react with gold, but does react with other metals. If a trace remains, then the gold is fake or of very low standard. Nothing will happen to genuine metal.
8. Look for gold in the sun and shade
Objects made of real gold shine equally strongly both in the shade and in direct sunlight. Admire the product in different lighting.
If in doubt, take an object that is definitely made of gold and compare the intensity of the shine.
9. Test with black bread
The method is safe (for real gold!), but slow. Take the crumb of black bread, remember, mix with water and stick the mixture onto the product. Leave it until the bread crumb turns into a dry crust, then break it apart.
If there are dark traces inside the crumb, it means the fake has oxidized. If not, then it is either gold or good gilding.
10. Run gold over tile or unglazed porcelain.
On unfired ceramic tiles or porcelain that is not glazed, gold will leave gold marks. After counterfeiting, the marks are gray or black.
Just draw with inconspicuous parts - fasteners, fasteners, so that it is not so noticeable. Gold may leave no traces at all on fired tiles.
11. Go to a pawn shop
In the pawn shop there are professionals who have an eye for gold. Invite the seller who wants to sell gold off his hands to go there with you - they say, let them evaluate the product.
The service costs 500 rubles, rarely more. But if you pretend to be a potential client, you can get an estimate for free (then you’ll pretend that you’ve changed your mind about selling).
12. Go to a jeweler
Jewelers not only determine the quality of gold items by eye, but also have special instruments for this. For example, a device with the otherworldly name “DeMon-U” will not only distinguish real gold from a fake, but will also indicate the sample.
The check will cost a maximum of 1000 rubles, often less.
Don't try it on your teeth!
Gold is a soft metal, so if you squeeze it hard with your teeth, marks will appear. Agree, the seller will not like it and will force you to buy.
Athletes test their medals for the sake of photos. Moreover, gold medals are actually just gold plated.
By the way, fake aluminum behaves exactly the same way, so if the seller insists on a “teeth test”, don’t be fooled.
On the other hand, only a new product does not have even small scratches on the surface. If a person claims to be selling his used gold, but it appears to have only come from a factory, something is wrong here.
conclusions
If you buy gold secondhand or from an unverified store, use as many methods as possible to ensure the authenticity of the product. The main thing is not to try too hard, so as not to spoil the soft metal.
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Source: https://www.iphones.ru/iNotes/12-sposobov-proverit-zoloto-na-podlinnost-07-08-2018
Methods for determining the sample of gold and silver
Among the methods of assay analysis there are: droplet, muffle, chemical-analytical, touchstone analysis.
Most often, when determining a sample, the drip method is used (consists of applying a special assay reagent to the test sample) and analysis on a touchstone (features are applied to the stone with a product and an assay needle, after which they are moistened with the reagent and the color of both features is compared to determine the sample). The sample is also determined by an electronic detector using non-destructive testing.
Touchstone
An assay stone, or, as it is also called, a Lydian stone, is a block of black or dark color made of fine-grained siliceous slate rocks (black jasper or whetstone), without foreign inclusions and cracks, with a matte, carefully polished surface. With its help, the sample color of a given metal is determined by the color of the line applied by the metal being tested. Touchstone is a very hard mineral that is resistant to acids.
Immediately before testing, the stone is cleaned with charcoal and water, then lubricated with any vegetable oil (walnut, bone, almond) and wiped dry.
Assay needles
The assay needle is a brass strip about 6 centimeters in length, at the ends of which strips of metal are soldered with an already known hallmark, signed at the bottom of the strip on the brass part. For each sample, due to the difference in alloys, there are several different needles, differing in color.
Assay reagents
The assay reagent is a solution of salts of the alloys being tested or a solution of acids and mixtures. In the case of determining the gold sample (up to 600), a solution of gold chloride is used. On the test sample, this yellow reagent leaves stains, the shades of which determine the sample:
- light brown stain color – 583/585 gold;
- orange-golden spot color – 583/585 white gold;
- The green color of the spot is 375 gold.
The effect of acid reagents on gold alloys is as follows: they leave light spots of brown shades, and the lower the standard, the darker the spots. Standard acid reagents correspond to 375, 750 and 958 samples.
Gold and gold-containing alloys.
Qualitative testing is carried out when it is necessary to determine the presence or absence of gold in a particular alloy and in what proportion it is present.
First, a scraper or file is used to clean an inconspicuous area for gold. Then the cleaned area is passed over a touchstone, after which the stroke is moistened with concentrated nitric acid.
If the stroke dissolves without a residue, we can say that it is a gold alloy of less than 333 purity, or a silver alloy of less than 500 purity, or even a non-precious alloy. In the complete absence of gold in the alloy, its complete dissolution occurs with the acid boiling.
If the stroke turns brownish-brown, we have an alloy of gold from 333 to 500 samples. Acid has no effect at all on gold alloys above 500 fineness.
A quantitative sample helps determine the amount of gold in an alloy. To do this, a line is drawn on the touchstone with the alloy being tested. For comparison, take an assay needle and make several strokes of supposedly corresponding samples. Assay acid is applied across the strokes and the intensity of dissolution of the test alloy and the alloys of the assay needle is compared.
White metals and their alloys
To determine them, a touchstone is also used - a line is drawn with the test alloy and treated with acid for 585 standard. Depending on the color of the acid, the following conclusions are drawn:
- yellow color – palladium or its alloys,
- red color – white gold not higher than 500 carat,
- brown color - an alloy of white gold no higher than 500 carat with a high content of silver and base white metals,
- color without change - alloys of platinum or gold above 500 standard.
Silver
A high-quality silver sample: it is enough to scrape off a little of the alloy and drop in red assay acid. If it is an alloy of copper and silver, both metals will become sulfates.
Line quantitative test.
- Using a solution of chrompic - potassium dihydroxide. Leaves stains on silver alloys of at least 600 fineness, red in color, their intensity increases with increasing fineness of the alloy.
- Silver nitrate solution. Used for testing alloys 500, 750, 800, 875, 916, 925, 960 samples. The solution forms a gray-white coating, which becomes ashen as the grade of the silver alloy decreases.
- For alloys below 750 standard, you can use an acid reagent for gold 500 standard with the addition of chromium. If the alloy contains silver below 750 purity, a red coating will appear.
What error can the result obtained using a touchstone have? A method for determining the presence of precious metals in alloys using a touchstone was discovered quite a long time ago.
And although it does not provide 100% accuracy, it has a number of very significant advantages - it is quick to determine, easy to use, and there is no need to damage the alloy product. And having experience working with a touchstone, you can learn to determine the sample of a precious metal in an alloy up to several units.
The method makes it possible to carry out not only qualitative, but also quantitative testing of alloys of precious metals: silver, gold and platinum.
Application for operation with metals
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Source: http://aurumtrade.ru/opredelenie-probi-zolota/
Determining the gold standard at home: folk methods and modern devices
Gold is one of the most popular metals. It has always been in fashion; gold jewelry is still purchased by many people to this day.
Also, gold has always been a profitable solution for deposits and storing money, especially during periods of crises and economic instability. But because of this popularity, scammers have long appeared who counterfeit gold jewelry. No one likes to be deceived when buying expensive products. And therefore you need to understand and know how the gold standard is determined at home.
What is a gold sample and how to check it? Many people know that among gold products there are practically no items consisting entirely of this metal. And in most cases, they additionally contain other elements, such as silver, copper or nickel.
They are added to increase the strength of the alloy, because gold is a very soft metal. Sometimes this is done simply to diversify the color component - as a result, jewelry can become pink, reddish or even greenish.
A three-digit number is stamped on the gold—the hallmark itself. It indicates the ratio of the amount of precious metal in the jewelry. The hallmarks are different, for Russia, for example, the following are established: 375, 500, 585, 750, 950, 999. And these numbers mean how many parts of the metal in the jewelry out of a thousand are gold. For example, 750 standard - per thousand pieces of jewelry 750 is made of precious metal, that is, 75% of the jewelry is gold.
Unlike Russia and the CIS countries, in the rest of the world the quality of gold products is determined using karats. The maximum number of carats for the alloy is 24, which means that the jewelry is entirely gold.
To convert foreign carats into the standard we are used to (for example, when buying jewelry abroad), you need to do the following: divide the number of carats by 24, and multiply the result by a thousand. For example: 18 carat gold: 18÷24*100 = 750.
Result: 18 carats is equal to the 750th standard. By calculations you can get the following comparison table:
CaratsSamplePercentage of gold| 24 | 999 | 100% |
| 18 | 750 | 75% |
| 14 | 585 | 58,5% |
| 12 | 500 | 50% |
| 9 | 375 | 37,5% |
| 8 | 333 | 33,3% |
It is possible that the sample is missing. It may be missing if the product has been altered or restored.
Checking precious metal for authenticity
Before finding out what standard is on the jewelry, it is advisable to find out whether the product is made of gold at all. If it turns out to be just gold-plated, then there is no point in wasting time and determining the sample of the missing valuable metal.
The easiest way to identify gold is by using its magnetic properties. This metal practically does not react when a magnet approaches it. It is logical to assume: if the jewelry being tested is attracted to a magnet, then it is nothing more than a fake with gold. Although in the rarest cases the product may consist of gold, but of the smallest standard. However, it makes no sense to pay for it like gold.
However, there are other metals that are not magnetic, such as copper or aluminum, which is a disadvantage for testing with a magnet.
There is another simple way to identify gold. For this you will need ordinary vinegar. If the product is placed in a vinegar solution for some time, and no specific reactions occur and no changes in color occur, then the gold is genuine. If the check was carried out on a gold-plated fake, it would, at a minimum, darken.
A similar method can be used using iodine. The surface of the product will have to be scratched a little with fine-grained sandpaper. Next, apply iodine to this area using a cotton swab. If the treated part darkens, you have gold, since other metals will not react to iodine in any way. But this method has a clear drawback - the iodine stain is very ugly, and it is unlikely to be easy to remove.
There are people who can identify gold by ear. But few are capable of this, since it is actually very difficult. Individuals with an ear for music succeed in this, and, accordingly, in complete silence.
How to recognize this precious metal in this way? You just need to drop it from a small height onto a flat and hard surface. Gold is a ringing metal, and when it falls it will make a beautiful ringing sound, like crystal vibration.
If other metals predominate in the product, then the sound will be muffled, it will even hurt the ear.
Another simple way to detect gold at home is to test with bread. To do this, the product must be placed in the pulp of bread, only fresh bread. Bread should be stored in a cool and dark place. After a few days, take out and break the already stale loaf. If green traces of oxidation appear on the product, it means that it is not made of expensive metal or with large admixtures of other elements.
Determining the fineness of a gold product
Once it has been determined that the product is genuine, you can begin to determine its sample. You can find out using the following methods:
- chemical reagent - drop method;
- using an electronic detector;
- assay needle and touchstone.
Determination using an electronic detector
You can also determine the gold sample at home using an electronic detector. The principle of its operation is based on the electrical and chemical reactions of metals. You can find out the sample of gold very accurately, and it does it incredibly quickly - within five seconds.
Using the device, you can easily distinguish a gold-plated fake from a genuine product and even calculate the exact amount of gold in it!
The range for the detector is six to eighteen carats - range 333-750 for samples. The results obtained are shown in carats.
Despite all its capabilities, the price of such a device is not prohibitively high. Electronic detectors are available in any jewelry workshops, shops and pawn shops. But most people still believe that such a device is not suitable for home use, and purchasing it is not a cost-effective solution.
Determination using an assay needle and touchstone
An assay needle is a small stick made of brass. At the end, a thin needle is fused to it, consisting of a valuable metal of a certain color, which depends on the sample. The touchstone is a black beam consisting of fine-grained slate, necessarily polished to a smooth state. It can also be called whetstone or Lydian stone.
Before determining the gold standard at home, the stone must be thoroughly cleaned with charcoal and wood water, then thoroughly lubricated with oil and wiped dry.
After cleaning and lubricating the stone, you can begin checking. To do this, you need to draw a line on the stone with the product. It will leave a certain color on it, which will determine the sample. For comparison, usually another line is drawn next to the line, but this time with an assay needle of reference quality.
The check can be carried out in another way. To do this, the product itself needs to be scratched a little with a file and with the scratched area (having found out that this is not gilding), a line is already drawn on the stone. After this, a small amount of nitric acid is placed on it. The reaction will occur within five seconds, and the sample is determined by it. In this way, it is possible to determine the ratio of the amount of gold to the amount of other metals in the alloy.
For example, if a scratch completely dissolves after applying the reagent, this means that the jewelry is either made of 333 gold, or, which is much more likely, of low quality silver. If the scratch has not changed at all, then this is a sign that the metal in the jewelry is higher than 500 standard.
Gold of the 375-500 grade can be identified by the changed color of the line on the stone - it will change to brown. If the alloy contains no valuable metals at all, the strip on the stone will begin to boil from the applied acid.
Now you know how to determine the standard of gold, but finally I would like to note the following: by purchasing the jewelry you like exclusively from well-known manufacturers, you reliably protect yourself from the possibility of buying a fake.
Source: https://ProDragmetally.ru/o-zolote/interesnye-fakty/opredelenie-proby.html
Types of reagents for gold and methods for determining the sample
Unfortunately, even when buying gold in expensive stores with a good reputation, it is not possible to be 100% sure of its quality. There are many ways to test gold that can be done at home, but they are all unreliable and cannot be completely relied on. In a workshop setting, a gold reagent is used for testing.
Testing gold with a reagent
Types of reagents
In order to determine a sample using reagents, three types of solutions are used:
- gold chloride;
- potassium iodide;
- acid based.
Gold chloride is used to determine the purity of an alloy when it contains less than 70% gold. You can get the gold chloride reagent at home, but to do this you need to have aqua regia - a mixture of nitric and hydrochloric acids. To dissolve 1 g of gold, take 2 ml of each acid. For the reaction, a porcelain cup is used, placed on a sand bath, which is heated using an electric stove.
It is necessary to work in a fume hood or outdoors, because toxic fumes are released during work. The end of the reaction will be indicated by the release of brown vapors and the formation of a brown precipitate. The mass is dissolved in boiling water and ammonia is added. The precipitate will be gold chloride.
Acidic reagents. They are also called assay reagents, which are a mixture of nitric and hydrochloric acids in various proportions with the addition of distilled water. The proportions directly depend on the sample of the alloy that is being studied. Acid-based reagents are also suitable for the determination of metals that do not contain gold at all.
A solution of potassium iodide is used only for testing high-grade gold.
Testing procedure depending on the sample
1) 375 sample. This alloy is considered to have the lowest gold content among those used in the production of jewelry. In the USSR, it was often used to make wedding rings because it is wear-resistant and hard compared to alloys with a high precious metal content. The alloy can have different shades depending on the metals in the alloy. If you try to saw it, it will be difficult.
When tested with gold chloride, a characteristic greenish-brown stain appears at the cut site. If the sample is lower than stated, the stain is dull or dirty with shades of grayish. If there is no gold at all, it is black.
The acid reagent for sample 375 consists of nitric acid (59.5%) and water (40.5%). When the metal of this sample is exposed to the reagent, a clear drop remains, in some cases slightly dark, but this is barely perceptible. If there is no gold in the alloy or very little of it, a reaction occurs with the release of foam and a green precipitate.
2) 500 sample. Rarely used for manufacturing. This standard is placed on all jewelry with 585 standard, coming from abroad, and on jewelry that, when tested, turns out to be poorer in gold content than 585 standard. The typical color of the alloy is reddish due to the high copper content. The density and hardness are almost identical to 585, which makes them difficult to distinguish.
The testing method is as follows: first, a study is carried out using gold chloride, then an acid-based reagent. Gold chloride leaves a brown stain, while white gold leaves a light brown stain. The acidic reagent for this sample is pure nitric acid, which, in turn, is considered a universal reagent. When tested, it produces a yellowish spot or its absence.
3) 585 sample. Most popular in Western countries and the CIS. It replaced the 583 sample, which was common in the USSR at one time, in order to meet Western standards. In the carat system it corresponds to 14 carats. The testing procedure is the same as for the 500 sample. First - gold chloride, then - acid reagents.
Gold chloride leaves a clean drop on 585 standard, in some cases with a barely noticeable shadow. On white gold of the same standard it has a golden-orange color. The acid reagent is a mixture of four drops of hydrochloric acid added to 46% nitric and 54% water. When interacting with an acid reagent, the alloy gives a slight burn for sample 500, a light brown stain for sample 585, and a dark brown stain for sample 750.
4) 750 sample. High grade gold. White and colored gold are not found. Almost all of it is yellow, with light tints. Very popular in the West, where it is 18K. In our country it is not particularly in demand due to low operating characteristics and high cost.
It is used to make massive rings, which are made so that they do not bend. Due to the weight of gold, such rings are especially expensive; not everyone can afford them, and this does not always make sense, since they will bend and wear out.
Tested only with an acid reagent. Gold chloride can be used for clarification if there is a gross fake. Potassium iodide is used only when determining an alloy with a base metal content above 80%.
When interacting with an acidic reagent for sample 750, no reaction is observed. This reagent contains 59.3% nitric acid and 1.1% hydrochloric acid, the rest is water.
5) Samples above 900. Such alloys are highly soft and malleable. They have good casting properties, but poor wear resistance characteristics. Mainly produced:
- 900: gold coins, badges;
- 916: coins, foreign-made jewelry with hallmark 22K;
- 958: jewelry, wedding rings and foreign products with hallmark 23K;
- 999: bullion in banks, bullion coins.
A solution of potassium iodide leaves a bright red stain on these alloys. When reacting with acid solutions, no stain remains. For 900 samples, 69.2% nitric acid and 1.3% hydrochloric acid are taken. For 958 - 78.7% and 2.0%, respectively.
Reagents for testing gold
The product can be considered approved in the following cases:
- For sample 375 - no stain when tested with an acid reagent, greenish-brown - when tested with gold chloride.
- For 500 standard - no stain and a light brown stain from gold chloride, brown when testing a white alloy.
- For 585 - a transparent stain from gold chloride and light brown from the reagent. For white gold, an orange spot.
- 750 sample - a transparent stain from the reagent.
- High-grade alloys - a red spot from potassium iodide or its absence from the reagent.
Reaction of gold alloys to different types of reagents
Gold alloys differ from each other in composition and percentage of impurities. The metal sample can be determined using special chemical compounds. Reagents for gold are mandatory materials for workers in pawnshops, appraisal workshops, jewelry and antique stores.
Stages of gold testing
Each product made of precious metal that is imported or sold through retail chains is subject to testing. The process is controlled by the government Assay Office. The jewelry is stamped with a mark that indicates the percentage of gold in the alloy.
For example, 750 standard indicates that the noble metal contains 75%, 585 standard indicates 58.5%, etc. For convenience and systematization of branding, state sample systems have been developed, the most famous of which are metric and carat.
The latter is used in Western countries.
https://www.youtube.com/watch?v=plFDk8mPr3w
The process of testing gold products consists of several stages.
- Visual inspection of the product. Particular attention is paid to the quality of the mark, its clarity, evenness of lines and legibility. On fakes, the sample has an uneven structure, numbers and letters are difficult to see. In addition, careful examination of the symbols will help identify gilding or jewelry. A specialist, upon visual inspection of the jewelry, can easily determine its quality and whether it belongs to a particular group of alloys.
- Cleaning the product. With the permission of the owner, part of the surface of the jewelry is cleaned before testing. This is necessary to confirm that the item being tested is truly gold and not gilded. During work, needle files, finely cut files and a tool for precise processing of the surfaces of metal products - a scraper - are used. The procedure is performed from the inside of the product, as carefully as possible and away from the assay mark.
- Application of the reagent. After preliminary determination of the sample, a reagent is applied to the stripped part of the decoration in a vertical position. The drop should not spread. An important point is the exposure time of the assay material on the surface. It varies depending on the type of reagent and sample. Acids on metal with marks 375, 500 and 585 are kept for 5-10 s, and with mark 750 - 20 s. Gold chloride should be on the surface for 7-12 s, potassium iodide - no more than 5 s. Failure to comply with the time intervals will lead to distortion of the characteristic chemical reaction. At the end of the procedure, a drop of the reagent is removed with a napkin or piece of calico.
Applying the reagent to gold
Testing of jewelry is accompanied by characteristic reactions, according to which the alloy sample is determined. The procedure is relevant for products on which the mark has worn off and is difficult to see.
Types of reagents and their effect on gold alloys
Testing of gold jewelry is carried out using several types of reagents. Each of them is used for a specific alloy and has a characteristic effect on it.
Chlorine gold
Gold chloride is a reagent used for testing jewelry without specifying samples. Thus, you can find out whether the alloy being tested contains precious metal and in what quantity.
Gold chloride is suitable for detecting counterfeits. With its help you can distinguish real gold from gilding and costume jewelry. In addition, the reagent is applicable for white precious metal 500, 583/585.
When choosing a chemical for testing jewelry, you need to know that it only works on alloys with a gold content of up to 60%.
Acidic reagents
Acid compounds for testing precious metals are a mixture of nitric and hydrochloric acids in various proportions. Distilled water is added to them. For example:
- nitric acid density 1.5;
- hydrochloric acid, density 1.20;
- distilled water.
The amount of reagents directly depends on the samples of the alloys being studied.
The effect of acid reagents on gold is of two types. On some products they leave a light stain, on others they do not have any reaction. The chemical element does not affect high-grade alloys or leaves dark marks on them.
Each acid reagent corresponds to a specific sample for analysis: 375, 750, etc. The lower the gold content in the alloy, the more pronounced the color of the reagent stain.
Acidic reagents for gold determination
When testing gold alloys of 375, 500, 750 standard, acid-containing preparations leave a transparent drop on the cleaned area without any trace. In rare cases, a subtle light shadow appears.
If the reagent is dropped onto a product made of base metal, a certain reaction will begin on its surface, followed by bubbling and the appearance of a greenish precipitate. A specific unpleasant odor will also appear.
Potassium iodide solution
The product is used to test alloys with a high content of precious metals. This chemical is used to detect counterfeit metals that are resistant to other reagents. The reagent with a solution of potassium iodide does not work on alloys whose fineness starts from 900. On a product with a mark of 800 and on jewelry with high chemical resistance, a black or green spot will form with possible subsequent bubbling.
Method of using reagents
Reagents for gold can quite accurately determine their sample; they are convenient to use on a large scale, and not at home. Their use for testing begins with inspection of the product. Sometimes one glance at a sample is enough to identify a fake. The mark may contain asymmetrical symbols, curved shapes and images. The next step is to determine whether the alloy belongs to the group of low-grade or high-grade gold.
The surface of the product in a certain place is cleaned. This helps to find out if there is another metal underneath the gold layer or if it is a single alloy. The further procedure depends on the type of reagent chosen.
Gold chloride does not act equally on different compositions. To check the purity, the reagent is applied to the surface of the jewelry. Alloys from 585 to 999 samples will not react in any way to the chemical compound.
On products that contain half of the total mass of precious metal, gold chloride will leave a dark stain. If the material has a negligible yellow metal content, less than 50%, the reagent will cause a reaction in the form of severe darkening and the appearance of a precipitate.
The lower the sample, the richer the color and stronger the sediment.
When using gold chloride, you need to be very careful and observe the exposure time of the drug on the gold surface. The drop should be small and clearly lie in its place, without spreading throughout the entire product. After completion of the work, the chemical is immediately removed.
Before using reagents, the surface of the product in a certain place is cleaned
Nitric acid is considered the most accessible and common method of testing jewelry.
Using a pipette, drop the reagent onto the protected surface and wait a couple of minutes. When the acid hits the alloy below sample 583, the acid causes the release of gas. The lower the gold content, the more bubbling will occur under the drop.
After checking, the reagent is immediately wiped off with a small piece of cloth or paper napkin.
Potassium iodide is used in a similar way as the previous reagents. The only thing you need to remember is that the drug only acts on alloys with a base metal content above 80%.
Chemical reactions of various gold samples to reagents
The table below shows the reactions of alloys of various samples to one or another reagent.
Reagent/Sample Gold chloride Acids Potassium iodide| Below 375 | dirty dark green, gray-green spot | dirty dark green, gray-green spot | — |
| 375 sample | greenish-brown spot | — | — |
| 500 carat yellow gold | light brown spot | the drop remains transparent. Chestnut stain when using 585 sample reagent | — |
| 500 white gold | spots of different shades of brown | spots of different shades of brown | — |
| 585 yellow gold | transparent drop | bright spot | — |
| 585 white gold | golden stain | beige, golden or orange spot | — |
| 750 yellow gold | barely perceptible stain | barely perceptible stain | — |
| 750 white gold | light brown spot | light brown spot | — |
| 800 and 900 samples | — | — | dark red spot |
Safety precautions when working with chemicals
Chemical reagents are quite aggressive substances, so when working with them you must adhere to certain safety rules. This is especially true for the use of acids.
You need to lay a thick fabric on the surface where the testing procedure will take place. Hands are protected with gloves, clothing with an apron. Acids are diluted in a special container, added in a thin stream to distilled water. The liquid may become hot. Before using the composition on gold, it must be cooled.
Application and technique of working with touchstone
In addition to chemical reagents, you can test a sample of a precious metal with a touchstone. The mineral of natural origin belongs to the group of silicon shale and contains about 8% carbon, which gives it a black color. There are also artificial touchstones.
The use of a tool begins with its preparation. The surface is wiped with castor oil, then rubs are applied - dense strips no more than 2-3 mm wide and up to 20 mm long. Vertical lines are applied nearby using standard needles that correspond to a particular sample. The rubs are moistened with reagents and the reaction is observed. A dark precipitate in comparison with the reagent indicates a low gold content in the alloy, a light one, on the contrary, indicates a higher one.
The advantages of testing jewelry on a touchstone are the preservation of its integrity, the testing of any alloys, and the simplicity of the procedure.
Buying reagents for gold will be a justifiable expense if they are used in a workshop or pawnshop. For home testing, less complex materials are suitable. In addition, the person conducting the testing must have certain skills, because reagents are expensive, and their wasteful use can hit your pocket.
Source: https://1nerudnyi.ru/reaktivy-dlya-zolota-01/
How to check gold in a pawnshop
Gold is a soft precious metal and for this reason it is combined with various additives to create jewelry. The quantitative content of other additives is determined by the sample. For example, a 925 alloy contains 92.5% of gold itself, and the rest is alloy and all kinds of impurities.
In the Russian Federation, the circulation of gold, platinum and silver is strictly controlled by the relevant authorities, but this still does not provide 100% protection against counterfeiting. Fraudsters quite often overestimate the content of pure gold in the alloy or, in general, replace the precious metal with cheap analogues that only superficially resemble gold.
Reliable pawnshop: checking gold
There are many methods for testing gold - they all differ in degree of complexity, accuracy and price. There are metals that have physical properties similar to gold. One example is pyrite. This is a mineral with a characteristic metallic luster and golden color, and is essentially an alloy of sulfur and iron. Ordinary gold-plated copper also often acts as a substitute for gold.
In any serious pawnshop, the appraiser has professional tools and materials, including:
- magnifying glass;
- laboratory scales with an accuracy class of at least 3 or 4;
- calipers;
- calico;
- assay chemicals.
There are a large number of different chemical reagents. The rule is this: from 375 to 750 samples, acidic samples are used; up to the 600th standard, so-called chlorine gold is used; and potassium iodide is used to test alloys above the 800 standard.
How do they check gold in a pawnshop?
A step-by-step study of products is as follows:
- superficial inspection;
- cleaning with a tool;
- applying one of the types of reagent;
- final determination of the sample.
1. Inspection using a magnifying glass and other available means . The specialist, first of all, pays attention to the imprint and stamps. A counterfeit is easily determined by the naked eye - curvature in symbols and numbers. Also, upon visual inspection, it is not difficult to identify jewelry and gilding. In addition, it is possible to determine whether a metal belongs to the group of high-grade, medium-grade and low-grade alloys.
2. Surface cleaning . The surface can be smeared with dirt and dust, painted, bleached, treated with chemical compounds, so there is a need to clean a separate area of the product. The cleaning procedure is carried out exclusively with the client’s permission. The following tools are used for this:
- all kinds of scrapers;
- finely cut files;
- files.
Stripping is carried out as carefully as possible, and, most importantly, in a remote place from the mark. If we are talking about a ring, bracelet, earring, then cleaning is done only from the inside.
3. Application of reagents . An assay chemical is applied to the cleaned area. The drop is placed on the product carefully to prevent leakage in different directions. The presence of the chemical on the metal must be strictly controlled, otherwise inaccurate research results may be obtained. Finally, the drop is carefully soaked with calico or a napkin.
There are many different chemical reagents. And the duration of each person’s stay on the gold surface is strictly regulated:
- gold chloride – no more than twelve seconds;
- acid chemical reagent for the 375-585th and 750th samples - ten and twenty seconds, respectively;
- potassium iodide – from eight to twelve seconds.
4. Sample . The surface of the material is carefully checked with reagents, sometimes several at once, and is confirmed by the tabular instructions.
Samples are tested according to the following scheme:
- gold and other alloys with a precious metal content of up to 60% are treated with gold chloride, and after the corresponding standard with a reagent;
- 750 gold is tested with a standard reagent, but to detect handicraft fakes, you can limit yourself to gold chloride;
- alloys with gold from 80% are tested with a solution of potassium iodide.
Description of samples and their reactions to chemical compounds:
- 375th sample - a greenish or brownish stain from chlorine is obtained, and the drop itself is completely transparent;
- 500th - the chlorine stain turns brown, and the very drop is transparent and clean;
- 585th - a golden or yellowish stain from chlorine, and a light brown stain from a standard chemical reagent;
- 750th – the stain is often absent or barely noticeable;
- The 750th sample of the so-called “white gold” is a bright brown spot;
- 800th - potassium iodide produces a dark, rich red stain;
- 900 and higher samples - a light red spot is obtained from a solution of potassium iodide.
How do they check gold in a pawnshop using a device?
Today, there are special instruments with which it is possible to identify precious metals. Non-destructive express testing is based on measuring the electrochemical potential of the material.
Electronic testers are the most common devices. They use drops of liquid to scan an existing sample and determine its purity. In laboratory conditions, the X-ray method has become widespread. In this way, not only the precious metal content is determined, but the full composition of the alloy is also decomposed.
Alternative to advanced tests:
- magnet – if metal is attracted to a magnet, then you are dealing with a fake
- vinegar – if the product tarnishes in vinegar, it is not real gold;
- glass - gold can be rubbed across the glass, no traces should remain, since gold is much softer;
- porcelain - if the gold strip remains yellow, then it is most likely gold;
- iodine - gold reacts with iodine, namely, a darkened stain remains at the site where ordinary iodine was applied.
Sennaya Pawnshop is a guarantee of reliability and quality: we quickly and accurately determine samples of precious metals. We accept gold in the form of commemorative coins, bank bars, jewelry, and scrap.
- Sennaya square, building 6 (Metro station Sennaya, Spasskaya)
- Yaroslav Hashek str., building 4/1 (Metro Kupchino)
- Varshavskaya st. house 108 (Moskovskaya metro station)
- Ave. Veteranov, building 140 (Metro Ave. Veteranov)
The lending rate is 0.39% per day.
The lending rate is 0.35% per day.
The lending rate is 0.35% per day.
The lending rate is 0.39% per day.
Source: https://sennoy.spb.ru/blog/kak-proveryayut-zoloto-v-lombarde/
Types of reagents for gold and methods of using them
One of the accurate methods for testing gold is the method using reagents. A gold reagent is a substance whose reaction can be used to determine the presence and amount of gold in an alloy. Depending on the gold sample, a different reagent may also be needed. Moreover, for a more accurate determination, it is often necessary to conduct the experiment several times using different reagents.
Potassium iodide solution
This solution is used to test high purity gold alloys, as well as to identify good counterfeits, that is, those made from alloys that are inert to most substances. The solution works like this:
- On an alloy with a gold content above 90%, the reagent forms a bright red spot.
- On gold alloys with a gold content of 80 to 90% there is a burgundy stain. This gold alloy is often found in scrap left over from dental crowns or dentures.
- On counterfeits made from alloys that are highly resistant, a black or green spot forms, but turns black. The reaction is accompanied by the release of bubbles.
Description of reactions for samples
Thus, we can consider that a sample has been identified when the following reactions are observed for it:
- 375: when reacting with gold chloride, a greenish-brown stain is formed; there is no reaction when interacting with an acid reagent for this sample.
- 500: when reacting with gold chloride, a light brown spot is formed, with a standard reagent - a transparent drop. If a 585 sample reagent was used for clarification, the 500 sample will have a chestnut-colored spot.
- 500, white: from gold chloride - a brown stain.
- 585: from gold chloride - a transparent drop, from the reagent - a light spot.
- 585, white: gold chloride will leave a golden-colored stain.
- 750: subtle stain from gold chloride, same for acid reagent.
- 750, white: the reagent causes a light brown stain.
- 800: dark red stain - from potassium iodide.
- Above 900: red spot - from potassium iodide.
Procedure for testing.
First of all, the product is inspected. Attention is drawn to the mark; sometimes if it is fake you can tell visually. For example, there may be asymmetrical symbols, and the shapes and images themselves may appear crooked. Next, it is necessary to determine whether the alloy belongs to the group of high-grade or low-grade gold.
Before starting the study, the surface of the product in a small area is cleaned, since it can be covered with a layer of another metal, for example, simply be gold-plated or rhodium-plated. Cleaning is carried out carefully, far from the assay mark, on the inside of the product.
A drop of the substance is applied to the cleaned surface. It should lie very carefully on the decoration. When determining the results, it is important to strictly follow all recommendations and monitor the time the drop remains on the surface of the product. After the reaction is complete, remove the drop of reagent.
The use of gold reagents is not the only method for determining its purity. This research can also be done using touchstone and assay needles. There is also a special device for testing gold. But the reagents have sufficient accuracy and are convenient to use, say, in small workshops.
Source: https://HochuZoloto.com/prochee/reaktiv-na-zoloto.html
