Are "999", "990" and "925" the same? What kind of silver are they?

Review expert: Gan Qiang, lecturer at Beijing Institute of Technology, PhD in Applied Chemistry

From ancient times to the present, people have always loved silver products. Silver, as a symbol of wealth, has long been a hard currency in the market; silver can be turned into exquisite ornaments to decorate people's faces and lives. In the story, "silver can be used to test poison" is a magical plot.

Source: Xinhuanet

In modern life, silver still plays an important role in our lives, such as silver bowls used in weddings and funerals; and the dazzling array of jewelry in jewelry counters... We have also heard and learned more about "silver" during our travels. The Miao silver jewelry is dazzling, and the Tibetan silverware is simple and gorgeous... So the question is, what is the difference between these silver and pure silver?

Sterling silver, Miao silver, Tibetan silver

Silver is a heavy metal that exists in nature as a single substance, but most of it exists in silver ores in the form of chemical compounds. Silver has relatively stable physical and chemical properties, good thermal and electrical conductivity, soft texture, high ductility, and a reflectivity of more than 99%, so it has a wide range of uses.

Source of silver obtained by electrolysis | Wikipedia

When we go to regular merchants to buy silver jewelry, it is not difficult to find that there will be a number written on the label: "925", "990" or "999". These three numbers actually represent the silver content . For example, the highest purity of 999 silver is "999", which contains 99.9% silver and is easily oxidized and turned black when worn. The second purity is "990", called pure silver, which contains 90% silver. "999" and "990" belong to the types with high silver content, so the texture is softer and is generally used as plain silver jewelry. Therefore, in order to make more jewelry with different shapes, the familiar "925" silver made its debut. It is also called international standard silver , which adds 7.5% copper alloy components and is the lowest standard recognized as pure silver internationally. In the pure silver family, the advantage of 925 silver is that its hardness is increased, which is more suitable for making flower-shaped jewelry.

Miao Silver Source: Xinhuanet

The Miao silver commonly seen in Miao settlements is not pure silver. The intricate and gorgeous designs and glittering luster of Miao silver jewelry are all brought about by a little "addition". When making silver jewelry, other alloys are added to increase the hardness of the jewelry, so that complex shapes such as birds, beasts, insects and fish can be made. Therefore, many times the silver content of Miao silver products we see or buy is usually less than 15%. What's more, there are some that are named "silver" but have no content, and their appearance is also the result of electroplating of all copper.

Source of Tibetan Silver丨Xinhuanet

The silver content in Tibetan silver is also not high. Tibetan silver is not pure silver in Tibet. It is just a name for an alloy, made of 30% silver and 70% copper. This is also the standard for antique connoisseurs to identify Tibetan silver. However, the Tibetan silver on the market today is basically made of white copper, brass and red copper. This type of Tibetan silver, known as "three-color copper", generally does not contain silver.

How can consumers distinguish between genuine and fake silver jewelry?

There are numerous products with the word "silver" on them, and it still takes some effort for consumers to buy genuine sterling silver jewelry. Although the price of raw silver is not high, it does not prevent unscrupulous merchants from mixing cheaper metals such as cadmium, iron, and copper into silver jewelry in order to make a profit.

Even silver jewelry clearly marked with "999", "990" and "925" can still be fraudulent. This practice is full of hidden dangers. For example, cadmium is a harmful metal. If mixed in jewelry, it can easily cause human poisoning.

Source: unsplash

It is difficult for ordinary consumers to know whether the harmful substances in silver jewelry exceed the standard just by looking at the appearance. Only through professional instrument testing can we know. However, in judging the authenticity of silver jewelry, some relatively simple methods have been summarized:

Look at the color: high-purity silver jewelry has uniform, white, and shiny silver. If it contains lead, it will appear blue-gray; if it contains copper, the jewelry will not feel moist.

Weigh it: Since silver is slightly denser than common metals, if the jewelry feels bulky but light, it may be a fake.

Check the hardness: Silver is harder than lead and tin, but lower than copper. If you have any concerns after purchasing, you can use a pin to scratch an inconspicuous part of the jewelry for testing. If there are any subtle marks left on the actual object, it can be preliminarily determined to be silver jewelry.

Listen to the sound: sterling silver jewelry has no elasticity and makes a loud noise when it hits the ground, and the lower the purity, the lower the sound.

Why does silver turn black?

In life, people will find that silver jewelry turns black when they wear it. This is caused by the reaction between silver and oxygen in the air. This oxidation reaction will intensify as the temperature rises. If there are more compounds such as hydrogen sulfide, acidic gas, and nitric oxide in the environment, silver jewelry will turn black due to chemical reactions. Therefore, when silver jewelry turns black, we can use some small cleaning methods to treat the symptoms, such as cleaning it with a silver polishing cloth. The black silver sulfide on the surface of the silver jewelry can be removed by friction. Of course, the best way is to pay attention to storage and seal it when not wearing it to prevent it from oxidation.

Source: TV series stills

It is precisely because of this feature that the use of silver needles to detect poison has become a common plot in novels and film and television dramas. So, is this method of detecting poison scientific? In fact, the ancient silver needle method of detecting poison was based on the fact that poison was arsenic . Due to production limitations, there was a small amount of sulfide in ancient arsenic, and silver easily reacts with sulfur and hydrogen sulfide to form black silver sulfide. Therefore, the silver needle turns black when detecting poison, which is a chemical reaction caused by the contact between the sulfide in arsenic and silver, and does not mean that silver itself can detect poison.

In short, Miao silver and Tibetan silver are not pure silver, so be careful not to be misled when purchasing; pure silver has different categories, and you can choose according to your needs; silver jewelry can be real or fake, so please choose regular merchants to buy it, and if you have any doubts, seek help from professional inspection agencies .