Spinel is found in a large range of colors, it totally depends on the type of pollution that it suffered.
The red spinel gets its color from chromium and iron.
Red spinel is the most popular. A blue spinel may more often its color out of iron than cobalt.
Sometimes spinel contains inclusions of magnetite or apatite.
Spinel from Sri Lanka may have inclusions of total zircon. Spinel occurs in granite and metamorphic rock and occurs in the
United States, Sweden, Italy, Turkey,
Pakistan, Brazil, Australia, Myanmar (Burma), Sri Lanka, Madagascar, etc..
Spinel may be present art to corundum (sapphire, etc.).
Crystal Structure: Cubic
Composition: Magnesium Aluminum Oxide
Refractive index: 1.71