Spinel
| Category |
| Spinel |
| Crystal Form |
| Cubic |
| Moh's Scale Hardness |
| 7.0–8.0 |
| Specific Gravity |
| 3.60 |
| Refractive Index |
| 1.71–1.76 |
| Sources |
| Cambodia, Myanmar, Sri Lanka, Madagascar, Tanzania, Nigeria, Afghanistan, Pakistan, Thailand, Brazil, Russia, Sweden, Canada (Ontario and Quebec). |
For many centuries, along with many other red gemstones and including corundum deposits, it was believed that the spinel was a ruby. Until 1783 the discovery was made and spinel was identified as a different mineral species. The Black Prime's Ruby mounted on the Royal Crown Jewels of England has been mistaken for a ruby is actually a spinel.
The word "spinel" is originated from the Latin word "spinella" which means "little thorn", which describes the sharp points of the spinel's octahedral crystals. Spinel is commonly found in red colour and hence red spinel sometimes are called "ruby spinel" or "pigeon's blood". However, spinel occurs in wide range of colours such as yellow, pink, orange, blue, green, purple, brown and black. Blue spinel was discovered back to the Roman period (51 BD to 400 AD) in England.
Treatments
Spinel is rarely heat treated or irradiated to change or improve colour.