Learn About Alexandrite Gemstones
Alexandrite Gemstone Properties
Alexandrite gemstones are known as a phenomena gemstone. Alexandrite gems are known for the extraordinary feature of its ability to change its color. In daylight, Alexandrite is a green or bluish green color. In incandescent light it will change to a red hue or a reddish shade with brown or greenish undertones. This phenomenon makes Alexandrite one of the most expensive gemstones in the finer, larger sizes. As a member of the Chrysoberyl family of gems, Alexandrite is among the most brilliant of gemstones and is only surpassed in hardness by diamond and corundum. What makes Alexandrite gemstones color change ability so unique is minute trace elements of Chromium. Regular Chrysoberyl gemstones contain iron and titanium but no chromium. Also accounting for the relative rarity of Alexandrite gemstones is the unique geological environment that it is found in. The elements necessary to form Alexandrite are found in two distinct rock types which also lack silica which is overly abundant in the earths crust. This type of geologic environment is very similar to metamorphic emerald deposits, if the silica mineral is present, than emerald will occur instead of alexandrite. The proximity and lack of silica in these two rock types is a very rare occurrence which is why alexandrite is a very rare gemstone.
Alexandrite Gemstone History and Lore
Alexandrite was discovered in 1834 at an emerald mine near the Tokovaya River in the Ural Mountains of Russia. It was discovered on the very day of Czar Alexander II birthday, thus this new chameleon like gemstone was named after him. The green and red colors of Alexandrite are the same as the official colors of the Russian Imperial Guard so Alexandrite gemstones became the official gemstone of Tsarist Imperial Russia. It became very popular in Russian antique jewelry because it was greatly admired by the old master Russian jewelers. Victorian jewelers also used Alexandrites in Victorian jewelry.
Alexandrite Gemstone Sources and Occurrences
The major source of all Chrysoberyl varieties is the Brazilian state of Minas Gerias (means general mines). Here, at a mine called Lavra de Hematita in 1987, the world's largest find of gem quality Alexandrite were produced. Estimates of up to 50 kilograms of very high quality rough, some up to 30 carats in size, were produced in less than 3 months! The Alexandrite gemstones produced from this mine are still coveted today due to their very fine color change. The original Russian deposit is now exhausted. Sri Lanka produces good quantities of Alexandrite, from gem gravel deposits. The last major source of Alexandrite was discovered near a village called Tunduru, not far from the Ruva River that defines the Tanzania/Mozambique border, in 1993. This gem deposit has produced world class gems although production has been very low since the late 1990ís. India is the latest producer of large, clean alexandrite gems but the color change characteristics are not of top quality.
Alexandrite Gemstone Evaluation and Valuation
Alexandrite is a color change Chrysoberyl. The closer the colors are to green and red of a pure hue the higher the value. Secondly the better the color change the higher the value. Either the green or red must be of a good hue. The degree of color change can only be truly evaluated with a single light source in a dark room. Traditionally a candle is the best light source to evaluate the red color! Although clarity is a significant factor in evaluation, an alexandrite with a poor clarity rating with a 100% color change is more valuable than an alexandrite with a 50% color change and a high clarity rating. Fine quality stones over 2 carats are both very rare and very expensive.