BeAl2O4 with Fe,Ti. Orthorhombic. Colors: colorless, green, yellow, blue green, deep green, red, violet, honey, pale yellow....Highly attractive gems closly resembling sapphires, can be used in jewelry as it is one of the hardest and toughest gems. The cat's eye variety is cut en cabachon and display an optical phenomenon known as "chatoyancy".

Another variety displays a color change efect and is known as Alexandrite. The best quality alexandrite traditionally came from Russia, until more recent mines like in Brazil, Madagascar, India, and Sri Lanka started productions. Chrysoberyl is a beautiful gemstone by itself. It occurs in yellow, yellowish green or brown color but it is better known for its color change variety, Alexandrite, or the exceptional cat?s eye phenomena it can show. Alexandrite is named for the former czar of Russia, Alexander II, and was first discovered in the Ural Mountains of Russia, supposedly on the day of his birth. Chromium gives alexandrite its color change property fluctuating between green in fluorescent or daylight to red in incandescent light. Cat's eye chrysoberyl is known also as cymophane.

The effect is caused by microscopic needle-like inclusions that reflect light into a single dynamic sliver of light running along the center of the cabochon and make it like a living cat's eye. Simply faceted transparent chrysoberyl is usually found in yellowish green to green, yellow and shades of brown. It is a very fine gemstone associating beauty and durability. Typically from granite pegmatite and mica schists (in Russia, Sri Lanka, Madagascar, Brazil?) the finest qualities for this rare stone can be found also in Mogok, Burma (Myanmar), in the pegmatite areas in the west of the Mogok valley in Sakangyi or Barnarmyo, and in different secondary alluvial placers in the Mogok Stone Tract near Mogok, Kyatpyin towns and Barnardmyo village. Mineral collectors appreciate chrysoberyl crystals for their beautiful twins. The most interesting and researched chyrsoberyl twins are the cyclic twins. These crystals appear hexagonal but are the result of a triplet of three "twins," with each "twin" taking up 120 degrees of the cyclic trilling.