Crystal skulls are usually made of some type of quartz crystal and are generally found in Mexico and Central America but also have been found in Tibet, Peru, and Russia. The skulls are usually shaped like human skulls ranging in size from 1 inch in diameter to 7 inches in diameter or even larger.
Some skulls are anatomically correct while others are just crude replicas.
There are skulls that show the definite shape of the teeth, while others do not. Modern skulls are usually identified more readily by the stroke marks of the jewelers wheel seen in the crystal. Since the fourteenth century, craftspeople used jeweler's wheels powered by hand or foot. The wheels today are made of metal and coated in diamonds and are electronically powered. A skull with carving strokes in a circular motion from a rotary wheel would be identified as contemporary.