Chrome is a special variety of green tourmaline that owes its vivid green hue to trace amounts of chromium and vanadium. It should not be surprising, therefore, that the finest chrome tourmaline tends to resemble the finer examples of emerald and tsavorite. Chrome tourmaline is actually a distinct tourmaline variety called chrome dravite, found in East Africa. It is often associated with tsavorite garnet; miners will usually concentrate their efforts on tsavorite, as it fetches higher prices. HistoryThe chrome green tourmaline was found long ago in Africa, in the Ural Mountains in Russia and other passes in Europe, but more important discoveries were made in North Amrican and South America. Gem-quality stones were discovered in the early nineteenth century in the United States in the state of Maine, on Mount Mica near the city of Paris. In 1972, the mine nearby Newry, in the same regin, gave an exceptional quality PRODUCTION for a short time became the world's leading source of high quality stones. Around 1860, the first expeditions in search of gold explorers led the San Diego County, California, where they discovered the pink tourmaline. Another rare variety is particularly attractive chrome tourmaline from Tanzania, a very attractive green color caused by chromium, which is the same coloring agent of the emerald. HueLike emerald and tsavorite garnet, fine chrome tourmaline is a visually pure "forest" green with slightly yellowish to bluish secondary hues. The blue will normally show itself in incandescent light, the yellow will be more visible in daylight. The same criterion applied to tsavorite garnet and emerald is applicable to chrome tourmaline. A blue secondary hue is preferred to yellow. The product, unlike emerald, can never be said to be too blue. A visibly pure to slightly (five to fifteen percent) bluish green gem between seventy and seventy-five percent tone is the most desirable. CrystalGenerally speaking, the material is simply more opaque than emerald or tsavorite garnet. Its hue is vivid but it is also dense. A chrome tourmaline that meets the criteria discussed above and that exhibits good crystal — that is, one that retains its transparency in incandescent light — is the crème de la crème of this species. Multicolor effectAs tourmaline is the most dichroic of gemstones, a strong multicolor effect is to be expected. However, perhaps due to its unique chemical composition and its distinctly dark tone, multicolor effect is rarely observed in the chrome green(CAS No.:1308-38-9) gemstone. The rarity factorChrome tourmaline is quite rare generally, and particularly rare in sizes over one carat. A stone of fine quality over one carat is very rare. Therefore, the collector should expect a large percentage increase in the price of stones in carat-plus sizes. The next jump in rarity occurs at five carats. Stones of fine quality above ten carats are extremely rare, so rare in fact that I have never seen one.
Chrome refers to the element chromium. The metal itself is not used as a solid but is always electroplated onto another surface, such as steel, aluminum, copper, brass, stainless steel or plastic, a
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