Cat's eye green is a color. "Cat's eye" is not the name of a gem, but an optical phenomenon on some gems. That is, when a semi-spherical gem is irradiated by strong light, a narrow and bright reflection will appear on the surface, which is called "cat's eye flash" or "cat's eye live light", and then it will be named according to what the gem is. If the gem is in season, it will be called "quartz cat's eye", and if it is golden emerald, it will be called "golden green cat's eye". There are many kinds of gems that may have a cat's eye flash. According to statistics, there may be as many as 30 kinds. Besides quartz cat's eyes and golden green cat's eyes, there are also "pyroxene cat's eyes" and "aquamarine cat's eyes". Because the golden-green cat's eye is the most famous and precious, it is also called "cat's eye" for short, and other cat's eyes can't be called that. Emerald is a gem-grade green beryl, which is emerald green, glassy, transparent to translucent.