Alexandrite is the well known but very rare color-changing form of Chrysoberyl. The color change occurs when Alexandrite is viewed under different lighting conditions – generally under daylight, it is usually greenish, but under incandescent light it appears either red or pink. For more information on what causes color change, you can refer to our Gemstone Phenomena page. The gemstone Alexandrite is so associated with color change that the effect itself is sometimes referred to as the Alexandrite effect. It also displays a separate color-related effect known as pleochroism, meaning it can change color based in the angle the stone is viewed from.
Etymology & Sources
Alexandrite is named for the Russian Emperor Alexandar II, and the folklore surrounding the gem suggests that it was discovered on the day of that the future emperor came of age, and was thus named in honor of him. What we do know for sure is that Alexandrite was first discovered in Russia, and that it was declared to be the ‘official’ gemstone of what was then the Russian Empire. The Russian source for Alexandrite has been depleted for some time, but nowadays Alexandrite can be found in Brazil and Myanmar as well as some other countries.
Alexandrite is a term exclusively used to describe the color-change variety of Chrysoberyl, so all Alexandrite will display the color change effect to some degree. Generally speaking the gemstone will appear as anything from blue-green to yellow-green in daylight, and in incandescent or other light with more red-spectrum light, it will appear red or pink. Generlaly speaking the more pronounced the color change and the more vivid the colors, the more valuable the individual gemstone. Most alexandrite has excellent clarity and a vitreous luster. Alexandrite is typically cut into the common gemstone shapes, and because large Alexandrite stones are exceedingly rare, usually the stones found will be relatively small.
Alexandrite, like other regular Chrysoberyl, has excellent hardness and reaches 8.5 on the Mohs scale, making it a very durable stone for use in jewelry. It has a specific gravity of around 3.5-3.8 and refractive index value of about 1.75.
Due to its rarity, large Alexandrite stones are infrequently found and most jewelry available on the market will use smaller stones. It has excellent hardness and is suitable for use in any form of jewelry. Genuine Alexandrite can be very expensive and it is probably best to purchase it as a gift only on very special occasions. Due to its uncommon and exotic nature, Alexandrite is used most often as a centerpiece gemstone for high end jewelry.
Alexandrite Cat’s Eye – The even rarer form of Alexandrite that not only displays color-change, but also exhibits Cat’s Eye Chatoyancy.
Alexandrite is not usually treated or enhanced. Synthetic Alexandrite can be created, but the cost is so expensive that often Synthetic Alexandrite has a similar price to the natural kind. Buyers should be aware that sometimes synthetic Spinel or Corundum can be enhanced to display the color-change effect, and this is sometimes passed off as either natural or synthetic Alexandrite.