Spinel, which is a genuine and much revered gemstone, suffers from the misuse of its name to denote synthetic stones. At one time, before refractive index testing of gemstones, red spinel was thought to be some sort of a ruby variety, and was termed balas ruby. Spinels occur in reds, yellows, blues, purples, pinks and greens, and are increasingly valued. You may be more familiar with spinel than you realize, as the Black Prince's Ruby, which is positioned above the Cullinan diamond in the British coronation crown, is actually red spinel.