The birthstone for those born in June and one of the popular choices for a fifty-fifth wedding anniversary, Alexandrite is the color change variety of the mineral species chrysoberyl. When this gem is illuminated by sunlight and many types of fluorescent light, which contain a large number of green and blue rays, its color is green. Under candlelight and incandescent light, which contain more red rays, the stone appears red. Fine alexandrite is a rich purple-red in incandescent lighting and a rich bluish green with daylight.

Alexandrite is a fairly modern gem, unknown before 1830 when it was discovered in Russia's Ural Mountains. Discovered on Czar Alexander II's birthday, the day he became of ruling age, the stone was named after him. Also notable is that the gem's green and red colors were those of the Russian military. Alexandrite is still looked upon as a stone of good omen in that country.

Until recently, the most important sources of alexandrite were Russia and Sri Lanka. Mining of this gem in Russia probably peaked late in the 19th century. In recent times a number of sources of good quality alexandrite were discovered in Brazil and Tanzania. The Hematita mine in Brazil has been touted as producing the finest known alexandrite. Some collectors, however, will always argue that the Russian material is the finest. Alexandrite as found in gem form can vary in weight from country to country but rarely weighs over from one to three carats.

The rarest of all birthstones, alexandrite finds acceptance in clarity grades that would not be acceptable in other gems. It is considered one of the world's most valuable gemstones. Even more rare and valuable is the Cat's Eye alexandrite, the variety of chatoyancy and color change phenomena.

Julie Lee is a web designer and founder of Julie's Jewelry Design, LLC. Julie's Jewels is a Texas based retail jewelry company specializing in high quality, affordable jewelry pieces created to be treasured for a lifetime.