When thinking of the most valuable gemstones on earth, Alexandrite would probably not jump to mind. But these amazing color change stones are so rare and beautiful that they can easily command $20,000 per carat for large top quality specimens. Fine large examples of this gem are so prized that even a one carat stone can sell for $10,000 per carat. How many gems share that lofty distinction?

A relative newcomer to the gem world, discovered in Russia in 1830 on the twelfth birthday of Czar Alexander II (hence the name) these stones exhibit a lush-grassy green in daylight and brilliant raspberry red under incandescent lighting. Red and green also happened to be the colors of the Russian Imperial Guard. Alexandrite was instantly believed to bear good omens.

The Russian source has long been depleted, and today's Alexandrite is predominantly produced in Sri Lanka. The quantity and size of alexandrite rough from Sri Lanka has been phenomenal, but the quality and brilliance of color change (Sri Lankan stones are more yellowish-green outdoors, and the red tends toward brown under artificial light) rarely measures up to the vivid hues found in Russia.

Unlike garnet and other stones with a color change variety, alexandrite will always exhibit a distinct change of color. Therefore, the more vivid each color and the more distinct the change, the more valuable the stone.

The true test of color change must be performed in a dark room with a single light source (preferably candlelight to bring out the red.)

Clarity also plays an important role in valuing alexandrite. Any flaws that block even color distribution will dramatically reduce the price.

On the other hand, inclusions are precisely what give cat's eye chrysoberyl its special effect. Although completely different in appearance, both cat's eye and alexandrite are from the mineral chrysoberyl. Tourmaline and other stones have a cat's eye variety, but the term when used alone always refers to chrysoberyl. Ranging from misty yellow to brownish-yellow, the most valuable hue is a rich-deep honey-yellow, and top quality specimens can fetch an impressive $5,000 per carat. Without the sharp eyes, though, the price can drop drastically to under $100 per carat.