Carbuncle

A precious stone, like a large ruby or garnet, of a dark, deep red color, said to glitter even in the dark, and to sparkle more than the ruby. The word is put to represent two different Hebrew words, one of which, Ex 28:17; Eze 28:13, is commonly thought to mean the emerald; and the other, Isa 54:12, may mean a brilliant species of ruby.