Fine alexandrite is exceedingly rare and expensive, especially in sizes over a few carats.
The finest color changes are seen in stones from Russia and Zimbabwe, but good stones are also found in Sri Lanka and Brazil. C at's eye chrysoberyl , often called simply catseye, is translucent yellow, brown, or green material containing very fine silk-like inclusions that produce a distinctive chatoyance. When cut en cabochon , this produces a very sharp linear reflection of light known as the cat's-eye effect. Fine, large catseyes are rare and costly. O rdinary transparent chrysoberyl is most often yellow, yellowish green, or brown in color.