Alexandrite is chrysoberyl BeAl2O4 with Cr3+ as an impurity, its colour depends on the type of illumination; in fluorescent light blue dominates, while red is predominant when viewed in light from a tungsten lamp. This is the so called "alexandrite effect". The most desirable colour change is rich blue–green to a deep raspberry red, and the shade of the colour can vary.
The impurity that produces the colour in alexandrite is Cr3+, but the ion sits in a different crystal environment and hence experiences a different ligand field. Synthetic alexandrite gemstones have been produced since 1973 and patented by Creative Crystals Inc of San Ramon, California.
QUOTE (in "Zandrite" by Marisa Spano on Mar 28 2009, 06:22 AM)
Zandrite is another trade and trademarked name for color changing synthetic glass laced with Neodymium.
Recent marketers and TV promoters of synthetic gemstones have started using the term "lab created", "created", "cultured" or "man made" to identify synthetics. Since synthetic corundum has been around for more than 100 years, even my grandmother's alexandrite jewelry might not be genuine.
Zandrite is another trade and trademarked name for color changing synthetic glass laced with Neodymium. It was named Zandrite because it sounds like Alexandrite and exhibits color changing characteristics simmilar to Alexandrite. I think this name belongs to Jewelry Television now.
Color change synthetic glass imitation of the Alexandrite emerged onto the TV shopping channels recently. Alexandrium - pink to violet color change glass and Zandrite, that exhibits color change due presence of Neodymium from pink in natural light to green under florescent light.