Realgar is an arsenic sulfide mineral. It was originally called “ruby sulfur” in early times because of its rich red to orange-red color and noxious components. Realgar has a long history of use as a poison (“bull’s blood”) in ancient Greece as well as a medicine in traditional Chinese and Indian Ayurvedic practices.
Corundum is an aluminum oxide mineral (Al2O3). The gem varieties of Corundum are Ruby and Sapphire. Ruby is the red variety of Corundum. The red color is caused by traces of chromium replacing aluminum in the crystal structure. Sapphire can be blue, red, pink, yellow, grey, or golden-brown. The most valued color is blue.
