Test tube stones. Synthetic minerals in jewelry

28 June 2020
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Starting with technology and ending with food, the life of a modern person is full of things created by himself. This is not necessarily something wrong, and yet the words "natural," "natural," or "sustainable" can be decisive in the purchase.

How justified is this in jewelry art? Let's try to figure it out!

The imitation game

Let's start by clearly separating "imitation" and "synthetic stone." Synthetic stones are those that, in appearance, chemical composition, and physical properties, correspond to natural counterparts. Their main difference is the laboratory origin. The process of their creation repeats the growth of minerals in natural conditions - hence the expression "artificially grown."

Imitation repeats only the appearance of the stone but not its composition and properties. Often, plastic or glass is used for this. Such inserts are often used to create jewelry but can also be found in silver. Our other articles found how to distinguish imitation from natural stones.

Test tube stones. The history of the invention of methods for growing precious stones

During the Renaissance, alchemists were interested in recreating expensive materials from cheaper ones. So, they began to pay special attention to practical metallurgy, mining, and medicine. Many people know the legendary "Philosopher's Stone" - a kind of reagent with the help of which metals were turned into gold, and the elixir of life was also created.

Although alchemy never became a serious science, it nevertheless impeded the development of modern chemistry and physics.

At the end of the 19th century, scientific achievements made it possible to create synthetic minerals. They not only did not differ from natural ones but also surpassed them in some respects.

Synthetic rubies appeared in Paris as early as 1885. They conquered the buyer with variety and price. But that was only at first. The popularity of synthetic rubies spurred manufacturers to raise the cost - in just a year, it doubled. However, fans of the gemstone still remained, and soon, artificially grown rubies disappeared from store shelves.

A revolution in this area was made by the French chemist Auguste Verneuil. In 1892, he developed a method for growing single crystals to create artificial gems. It was called the "Verneuil Method".

The scientist told the whole world about his success in 1902, and five years later, his laboratory turned into an industrial production that produced a ton of rubies in 30 furnaces.

Using the “Verneuil Method,” rubies were synthesized in industry, and later sapphires, spinels, alexandrite-like rubies, and other stones.

The main methods of growing gemstones: the Verneuil method, the Czochralski method, the hydrothermal method

The Verneuil method was the first industrial method for growing gemstones. It consists of the following: hydrogen is supplied to the burner with a nozzle directed downwards through the outer pipe and oxygen through the inner tube. Crushed aluminum oxide powder is added to oxygen, heated, and melted under the fire of detonating gas. Under the nozzle is a core of baked corundum - a crystal carrier. Molten aluminum oxide flows onto it, forming a ball of melt.

This method was standard only in Europe. It was used by Sodem Djevahirdjian in Sweden, Baikowski and Rubis Synthdes in France, and Weiders Carbidwerk in Germany. Since 1940, this method has been used in the United States when the Linde company launched the industrial production of corundum.

The second standard method is the Czochralski method. The melt of the substance for the crystallization of stones is placed in a refractory crucible and heated on a high-frequency inductor. The material of the future crystal is lowered into the melt on the exhaust shaft and increased to the desired thickness. Then, the shaft is rotated to distribute impurities and equalize the temperature evenly.

This method involves the production of synthetic corundum of any shape, so they are often used in technology.

The hydrothermal method of growing stones is also effective. The process is carried out in autoclaves filled with a solution of the desired mineral. The temperature is higher at the bottom of the mechanism, so when the saturated solution rises and enters the lower temperature conditions, it precipitates.

The hydrothermal method allows you to get jewelry stones of very high quality. For them, the American company Chatham produces rubies up to 60 mm in size.

Although the Verneuil method is considered classical, all three methods are now used and improved.

The work of human hands

Since corundums consist predominantly of aluminum oxide, the color is controlled by small impurities of other metal oxides. So, to obtain ruby, chromium oxide is used, sapphire - iron and titanium oxide, corundum with alexandrite effect - vanadium salts.

All these stones are analogs of natural ones. But separately, I want to talk about what is completely the work of man.

For example, a phianite (cubic zirconia) stone. According to its refractive index, this stone is close to diamond. In the light, cubic zirconia crystals give a bright dispersion in which you can see all the rainbow colors. With the help of impurities, you can get different shades of cubic zirconia: red, pink, orange, blue, and white, but not emerald.

The stone is named after the Physical Institute of the USSR Academy of Sciences (FIAN), where it was first synthesized in the 1970-1972s. But this name is familiar only on the former USSR and Eastern Europe territory. In other countries, it is better known as "zirconium" - Cubic zirconia.

An interesting fact is that cubic zirconia still has a natural analog - tazheranite. However, it was discovered later that cubic zirconia was synthesized.

Why synthetic stones are better than natural ones

Stones created by nature are a work of art, admirable. But, like works of art, they are not eternal. Deposits of natural stones are rapidly exhausted. Creating a stone in the laboratory can take about 2 hours and much longer in natural conditions.

Inspired by nature, a person managed to create something similar and a full-fledged prototype that surpasses its natural counterpart in several qualities. Jewelry stones are grown in ideal laboratory conditions, and therefore, the result is a high-quality material. Purity, color saturation, optical properties - all this is adjustable and gives freedom to the imagination of jewelers.

Synthetic stones are more wear-resistant. They do not react to oily environments and are more resistant to fading.

The undeniable advantage is the cost of the product. Jewelry with rubies, emeralds, and sapphires can now afford much more people than at the end of the 19th century. Beauty and accessibility - that's what the opportunity to create jewelry stones is.

What remains of natural stones? They are still used in jewelry but much less frequently. This is a luxury, inaccessible to many jewelry wardrobes. But the beauty of synthetic stone is equal to natural! The parallel with a work of art is again applicable here - natural stones and luxurious jewelry with them are an object of admiration rather than use.

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