Quartz is one of the most common minerals in the Earth's crust, and there are many different varieties. Tiger's Eye is an attractive form, usually cut into cabachons that displays an interesting optical effect known as chatoyancy. As the stone is turned in the light, a colored line moves back and forth across the surface of the stone. This is caused by parallel microcrystals of Asbestos within the quartz.

From what I understand, the original name of the stone was Cat's Eye, but when differing colors were discovered, the golden or brownish variety became known as Tiger's Eye, while the bluish colors were called Hawk's Eye. I have seen colors red, gold, blue, greenish, gray, and almost white. Some stones display more than one of these colors.

You should know that many stones have varieties that display chatoyancy, or a cat's eye effect. A good example is Cat's Eye Chrysoberyl.

South Africa is probably the main source of Tiger's Eye currently, but in the past, several areas including Germany and Sri Lanka produced the stone.