- Color: red, orange, yellow, purple, blue, green, grey
- Hardness: 8
- Refractive index: 1.71 - 1.92
- Density: 3.60 - 4.00
- Chemical composition: MgAl2O4
- Crystal structure: isometric
- Origins: Brazil, USA, Madagascar, Sri Lanka, Burma, Thailand, Cambodia, Afghanistan, Russia.
Spinel probably is the most commonly seen sapphire imitation. The most expensive spinels are purple, red, orangey-red and blue.