Black Spinel 6mm Round - 15-16 Inch Stone Type_Moonstone Black Tourmaline is a black

Black Tourmaline is a black crystalline aluminum borosilicate mineral with occasional light gray inclusions that appear as flecks or veins

and veins within the tan

and the green color is caused by a reaction in the stone when the chrome is introduced to water

with inclusions of white to colorless translucent or transparent

Black Spinel 6mm Round - 15-16 Inch Stone Type_Moonstone Black Tourmaline is a blackSpinel is a hard vitreous magnesium aluminum oxide, and comes in a range of other colors, but those varieties are transparent. Black Spinel not only has the dark color, but it is opaque as well, rendering its black especially deep and mysterious. Sometimes called the "Black Prince's Ruby" for its role in the English crown. It has been mistaken for ruby and sapphire at times, but can be distinguished by its structure and its lower relative hardness.