Russian Sibirlit (Chrome diopside)
Sibirlit (Chrome diopside) is a chromium-containing variety of the mineral diopside. The name of the variety comes from the name of the mineral species – “diopside” and chromophore admixture of the chemical element, whose ions cause the characteristic green color – “chrome”.
Russian chrome diopside
Chromdiopside has a color with a basic green color with an admixture of shades of yellow or blue, depending on additional chromophore impurities. Color, as a rule, is characterized by a high degree of saturation.
Chromdiopside was advertised under the trade name “Yakut emerald”, but since this term can be misleading about the mineral species, this brand was considered incorrect and not recommended for use.
Chemical composition: Ca (Mg,Cr)[Si2O6];
Crystal system: Monoclinic, Monoclinic-prismatic class of symmetry (point group);
Color: The main green color of chromdiopside is caused by the presence of an impurity of ions Sc63+, which isomorphically replaces magnesium in the structure of diopside, and yellow and brown shades are associated with an isomorphic impurity of Fe3+iron ions. In some varieties, the color is also affected by the isomorphic admixture V3+.
Physical property | |
| Hardness on the Mohs scale: | 5,5 – 6,5 |
| Density: | 3.22 – 3.40 g / cm3 |
| Cleavage: | by {110} average |
| Fracture: | uneven, step-rough |
Optical property | |
| Optical character: | anisotropic, biaxial (positive) |
| Refractive index: | np =1,663 – 1,669, nm =1,671 – 1,705, ng =1,693 – 1,728 |
| Birefringence: | 0,025 – 0,031 |
| Dichroism: | weak (yellowish-green – green) |
| Dispersion of light: | 0,017 – 0,020 (BG) |
| Luster: | glassy |
| Fluorescence: | sometimes there is a luminescence in ultraviolet radiation, which has a blue or brown color |
Green stones are a combination of warm green, the color of rebirth, the color of trees, herbs and flowers, and the cold geometry of crystals, smooth and cool faces, devoid of the seemingly vital juices of the earth. Green-the earth color that gives rise to everything growing on earth, and petrified, frozen harmony-merged into a symbol of eternity and inviolability, revered by the ancients, in an emerald-green stone.
Diopside is rich in green varieties: lavrovite, containing up to 4% vanadium oxide; smaragdite – an emerald-colored stone; known cat’s-eye diopsides. Of its many varieties, chromdiopside is undoubtedly the most beautiful. This is hard to guess from its name, but the fact that it contains chromium means that it is a green mineral. And this color is the second most popular in the modern jewelry world, and in the United States – so in General the first. The name “diopside” is derived from the Greek words dis – “double” and opsis – “appearance”. Diopside has pleochroism, the ability to change the hue when viewing the stone from different sides, for which it received such a name. Chromdiopside forms quite large transparent crystals, the best of which are jewelry raw materials,and chromdiopside translucent granular mass – ornamental stone.
Since its introduction on the market, this mineral has been confused with emerald because of its deep green color, and perhaps it would have competed for the primacy in the jewelry world of green precious stones, if not for its fragility.
In addition, the use of chromdiopside in jewelry is limited only to small stones, on average up to five carats, since in larger samples the color of the stone becomes so intense that it turns black.
The history of chromdiopside as a jewelry stone began recently, with the discovery of the richest Deposit in Yakutia, on the Inagli river, the right tributary of the Aldan. This happened in 1968, and its discoverer is a.m. Korchagin, who conducted a detailed study of chromdiopside and proved its jewelry value. Before that, it was known only by geologists and only as a rock-forming mineral. After this discovery, the Yakut emerald entered the jewelry market, but as an illegal one: no one knew about it yet, and so there were many people who wanted to earn easy money by passing off chromdiopside as an emerald. Anatoly Korchagin applied for the discovery of diopside in the same year that found him, but only after 18 years for the opening of the Inagli Deposit, he was given the diploma of the USSR Ministry of Geology, and was awarded the honorary title “Pioneer field”.
In 1988, free and official trade in chromdiopside as a precious stone became possible. Production of gem-quality material was carried out almost since Angliskogo deposits, the market got quite a lot of stones and it’s one of the reasons for the low prices on the Siberian emerald. It is safe to say that the chrome diopside is the most inexpensive natural stone jewelry like appearance. In addition to emerald, tsavorite (garnet group) and tourmaline have a similar shade of color.
Oddly enough, a wide circle of fans of chromdiopside is not known much; sometimes it comes to the point that its reputation as the “Yakut emerald” leads to the misconception that it is a type of emerald.
Siberian emerald is mined not only in Siberia. Many of its deposits are known: in Finland (Outokumpu), South Africa (Kimberley), Myanmar (Burma), China, Japan, France, Germany, Greece, Italy, Switzerland, Austria, Canada, Kenya, Angola, Australia, the United States, Russia, etc.
High-quality jewelry raw materials are extracted in the already mentioned Inaglinskoye Deposit in the Republic of Sakha and in Finland, the Outokumpu Deposit. Now chromdiopside is freely sold in Russia; mostly, it is small stones of 1-2 carats; this stone is often cut with an emerald step cut, baguette, square-in this form, the Yakut emerald best shows its aesthetic qualities. Both round and oval cut looks good. Low quality raw materials are cut with cabochons; in India, they even cut out beads from chromdiopside of various shapes, despite the fact that it is preferable to wear it in earrings or pendants because of its fragility. Chromdiopside is perfectly combined with yellow gold, it is very beautiful in black silver, and a diamond is considered an excellent match for it. However, he is also able to play a solo in a piece of jewelry, refuting those who do not consider it a gem due to the difficulties of working with it and the lack of the necessary hardness. Apparently, chromdiopside still has a time of glory, because for a gem 40 years of history is very little. Therefore, the Yakut emerald has not yet managed to acquire its own legends and beliefs. There is a legend that tells that in ancient times, flying through the sky over Yakutia, the God was carrying a bag with various precious stones, but frostbitten his hand and dropped the bag. The gems were scattered all over the land of Sakha: over mountains and tundras, along valleys and rivers. Since then, people find here and there placers of colored stones. Indeed, the participants of the expeditions to the Inaglinskoye Deposit say that all the surrounding hills and banks of the stream are covered with chromdiopside.
Main methods of gentrification
| Impregnation with adhesives | Strengthen, prevent cracking, improve the purity | |||
| Impregnation with various coloring agents | The change in color characteristics | |||
| Surface staining | The change in color characteristics |