Tools such as sandpaper or cutting wheels could easily explain the sharp edges seen in some of the skulls. The crystal skulls remains shrouded in mystery, but further research can help to unravel these century old enigmas. There are reportedly a dozen carved skulls made from rock crystal, milky white quartz and other crystals. The most famous of these is the Mitchell Hedges skull, believed to have been crafted in Central America during the late 19th century. Other similar skulls have been found in public collections dating back to the 20th century