Black Spinel 4mm Faceted Coin - 15-16 Inch Specimens and pattern

and pattern

It features:

Moonstone is a Feldspar mineral that was used in Roman jewelry nearly 2

midnight blue glass with flecks of copper suspended within it

which means

Black Spinel 4mm Faceted Coin - 15-16 Inch Specimens and patternSpinel 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.