Spinel
Spinel comes from the mineral class of oxides. The spinel owes its name to its octahedral growth form, which in Latin means spina, i.e. thorn or point. Also, the Greek word for sparks – “spinter”, could legitimately be the eponym.
Spinel, purple, Sir Lanka (4.58 ct)
Class: Oxide with simple chemical formula
Genesis: metamorphic and magmatic
Known varieties: Cobalt Spinel (blue)
Colors: purple, pink, blue
Hardness: 8
Optical effects: Star effect
Most important occurrences: Myanmar, Vietnam, Sri Lanka, Tajikistan, Tanzania, Afghanistan (spinel is found similar to corundum in marbles and other metamorphic rocks rich in aluminum).
Spinel has a high hardness. Spinel has a relatively high light refraction and no pleochroism, which means that if it has a continuous color, it will show it from all directions. Rare blue spinels in good color intensity may be colored by cobalt, among other things, a rather unusual cause of color for common gemstones.
Spinel, blue