SPINEL

Spinal comes in a wide variety of colors. The red and blue are the most sought, however. Their resemblance to the rubies and sapphires is notorious. The appearance in the last century, scientific instruments that can differentiate them, and have found that the "Black Prince's Ruby" and the "Timor Ruby", both the crown jewels of England, were in reality spinals.

Since the 20s, spinal is produced synthetically. It is used in the manufacture of doublets (a half stone which is natural and one synthetic) and in imitation of many gems, including garnet, amethyst, zircon, and sapphire, ruby and, of course, natural spinal.

The main deposits are located in Burma and Sri Lanka. Other mining sites, but whose production is of less importance exist in Afghanistan, Brazil, the United States and Thailand.

Characteristic

     Crystal system: Cubic

     Chemical composition: MgAl2O4 (magnesium oxide and aluminum)

     Color: All colors except yellow

     Hardness: 8.0

     Specific gravity: 3.60

     Refractive index: 1.71

     Dispersion: 0020

     Polychrome: None