Tips for stone care

How to distinguish artificial opal from natural?

Opal is an extremely interesting stone with an unusual history and properties. The Maxim Demidov blog already has articles about where and how this miracle of nature is mined, and what makes the Australian and Ethiopian varieties special. But there are other types of opals, for example, synthetic ones. In addition, opals are often imitated using glass or plastic, or by creating doublets and triplets. So that you can understand the features of natural stones and not confuse them with fakes and industrial analogues, we suggest that you familiarize yourself with this text.

Fakes and imitations

There are several types of fakes and imitations of opals made from different materials. The roughest are glass and plastic; special mention should be made of refined opals, which were born in natural conditions, but were improved with the help of technology. Synthetic opals also have the imprint of a factory machine, but they are not considered fake, although they are valued significantly lower than natural opals. Standing apart from this list are doublets and triplets, which are works of jewelry art and often belong to the class of high-quality products.

Glass opals

Glass opal Glass counterfeits of opals were invented back in antiquity. The technology for creating such stones is simple: the glass is heated strongly and then cooled sharply. After such processing, many cracks form in the glass, which are filled with air bubbles and special impurities, as a result of which the resulting material becomes similar to opal.

Opals made of plastic

Opal made of plastic Opals are also made from plastic, the multi-colored structure of which can imitate “opal” patterns. Moreover, the refractive index of plastic is even higher than that of natural stone: 1,48 -1,50 instead of 1,42 – 1,45.

Refined opals

Not all mined opals are of gem quality, so unattractive specimens are often subjected to special treatment. For example, they are often impregnated with smoke. Since opals have a porous structure, soot particles easily settle on them – as a result, the stone darkens and becomes more opalescent. opalescence – opal has a special property of flashing in different colors, and the flashes seem to occur inside the stone, and not on the surface. Traces of soot in smoke-treated opal Opals can also be tinted. Such stones are distinguished by their unnatural brightness and rich hue. Therefore, if you see bright purple, pink, blue or acid yellow stones, then most likely you are looking at a fake. Dyed opal

Synthetic opals

In 1964, Australian stone experts A. Gaskin and P. Darré patented the first technology for synthesizing opals. Nine years later, it was already used by a Swiss company named after the French chemist Pierre Gilson, which to this day produces opals of various colors and shapes. They have a denser structure and are less porous than natural specimens, while being much cheaper. Gilson opal The Japanese company “Kyocera” produces synthetic opals, but with a less natural composition. These stones are impregnated with special rubber, which increases the effect of opalescence and gives them a brighter, more intense color. Keutzer Opals Synthetic opals are also produced in China, Russia and Australia. They all have a similar chemical composition, but differ from natural stones.

Differences between synthetic opal and natural opal

In terms of chemical composition, synthetic opals can be completely identical to natural ones, but visually they always lose. If you have ever observed the incredible play of light in natural opal, then you are unlikely to confuse the opalescence of a natural stone with an artificial one. It is similar to internal flashes, which, during the rotation of the stone, either appear or disappear, and never stand still. Opalescence of opal in the “Tatting” ring In artificial stone, such magic almost does not happen, this is explained by its structure. Synthetic opal consists of small columns that are especially clearly visible when cut. With a loupe you can also see the pattern inside the opal, which is an orderly structure rather than a trick of light. Columnar structure of synthetic stones Another distinctive feature of synthetic opal is its scaly external structure, which is clearly visible through a magnifying glass in bright light. Scaly surface of synthetic stones

Doublets and triplets with natural opals

Doublets and triplets are characterized by multi-layering. If you turn them sideways towards you, you can see where the layers join. Doublets are made from a dark backing onto which a thin section of natural opal is glued. The result is an outwardly noble stone, often not inferior in beauty and properties to solid natural specimens. A good doublet can deservedly cost a lot of money. This is confirmed by the “Reflection of the Moon” ring from Maxim Demidov with a doublet opal weighing 13,85 carats. The incredible depth of color play earned the product 2019st place in the “Moment of Prestige” category at the Junwex XNUMX International Exhibition. Triplets have an even more subtle technology – here a plate of natural opal is located in the middle, between the dark base and the glass. The glass surface acts as a kind of lens and magnifies the beautiful patterns of the gem. Triplets turn out to be more voluminous and heavier, but not so much due to the opal, but due to the materials that surround it. Since the opal plate in triplets is very thin, they cost much lower than doublets.

Cost of natural opal

Natural precious opals differ from synthetics and imitations in their price. According to the Russian classification by A.E. Fersman, these gems belong to the 2nd order precious stones and are among the most expensive, along with morganite, aquamarine and spinel. Rings with natural opals from Maxim Demidov Noble white opals cost from 18 rubles per 000 carat, and the cost of noble black stones starts from 1 rubles per 200 carat. A price of several hundred rubles per 000 carat will indicate that this is synthetic or fake. Do you want to see all the splendor of opals with your own eyes? In the Maxim Demidov catalog you will find excellent products with the best examples of these stones and you can order a personal presentation of the products right at your home. Noble iridescent opal is a very rare and therefore expensive stone. It is mined in only a few deposits in the world, the largest of which are in Australia and Ethiopia. The price is also increased by the fact that opal is difficult to process. When cutting, many stones burst and crumble. Some are cut, but are destroyed during polishing. In a word, getting a neat stone for decoration is not an easy task. And since many people want to please themselves with such jewelry, unscrupulous businessmen decided to counterfeit the noble mineral. So before you buy jewelry, you need to figure out how to distinguish natural opal from imitation.

Imitation and artificial synthesis

  • fused glass;
  • compound (doublets and triplets);
  • artificially ennobled.

Note that there are also artificially synthesized opals. They are produced in laboratory conditions close to natural ones; colors are formed as a result of diffraction, just like real stones. The price of such opals is quite affordable for buyers with average incomes; the “ripening” of the stone takes up to one and a half years.

The most famous company synthesizing opals is the laboratory of the Frenchman P. Gilson. It is located in Switzerland, has been operating since 1974 and supplies the markets with stones of all colors: from black to white.

The second most popular is the Kiotsera company. Opals produced here are impregnated with colorless rubber to make them less brittle.

Gemologists have still not agreed on whether synthetic opal should be considered a fake. While pundits argue, jewelers and consumers around the world note the lower cost of synthesized stones, their greater strength and durability due to the lower water content in the structure. The disadvantages include perhaps a smaller number of inclusions and still the artificiality of origin – if this plays a role.

Fused glass + pigments

Visually, such a stone is very similar to natural, and it can be difficult to recognize. The sun will come to the rescue. Natural opal refracts sunlight and colors your fingers in reflections of the entire spectrum. Glass can’t do that.

In addition, the natural pigmentation is unique. The patterns are heterogeneous and do not repeat. If you see geometric correctness, clear boundaries of pigments, this is a fake, because in nature the transitions are soft, a little blurry.

If you have the opportunity to examine the stone under a microscope before purchasing, the glass will reveal itself by the presence of air bubbles in the cavities of the stone. They appear when heated to a high temperature and sharply cooled – this is the technology used to prepare glass imitation.

Compound opals

Composite stones are stones obtained by gluing together several layers. Depending on the number of layers, the opal is called a doublet or triplet.

A doublet is an imitation in which a piece of natural opal, processed and polished, is glued onto a dark backing (iron stone).

The triplet consists of three layers – a dark substrate, opal and a transparent glass “dome”.

These samples are many times cheaper than natural stones, and if you unfold them in profile, the layers will become visible. Natural minerals, of course, do not have any layering; they are transparent, and their structure is easy to see in the light.

Refined opals

This method is used for stones rejected by production. The main methods of refining them are impregnation with smoke and pigmentation with synthetic dyes. This approach becomes possible because natural opal stone has a porous structure.

In the first case, the mineral darkens due to pieces of soot – this is how expensive black opals are obtained, which are mined mainly in Ethiopia. These samples are affordable, but real black opals are very expensive.

The colors of opals, as mentioned above, range from black to transparent white, but they are all soft and natural. Bright blue, green or pink are refined stones treated with a chemical dye.

To summarize

The most basic criterion when choosing jewelry with natural opal should be the price. As already mentioned, this stone is rare and capricious; it simply cannot be cheap – even at an incredible discount.

You need to buy jewelry only in large jewelry stores – regular or online. These people value their reputation and will definitely provide a passport of the stone, which will indicate where it was mined from, if it is natural, or that you are purchasing an imitation.

The best way to check is to take the opal for gemological examination. Specialists from the laboratory will give an accurate answer, confirmed by analysis, whether this is a real stone grown in an ore vein, or an imitation, albeit of high quality.

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