Spinel
Spinel was historically mistaken for ruby and sapphire. The 'Black Prince's Ruby' in the British Crown Jewels is actually a spinel.
.jpg?width=760)
Spinel properties at a glance
| Type | Semi-Precious Stones |
|---|---|
| Chemical formula | MgAl2O4 |
| Mohs hardness | 8 |
| Crystal system | cubic |
| Luster | vitreous |
| Streak | White |
| Cleavage | Imperfect |
| Fracture | Conchoidal |
| Specific gravity | 3.6 |
| Transparency | transparent |
| Common colors | Red, Pink, Blue, Purple, Orange, Black |
| Rarity | uncommon |
Geology & background
Forms in metamorphic and some igneous rocks from aluminum and magnesium-rich parent rocks.
Many famous 'rubies' in crown jewels worldwide are actually spinels, including the Timur Ruby and Black Prince's Ruby.
How to identify Spinel
- Check whether the specimen's color and texture match typical Spinel examples.
- Photograph a fresh surface in natural light and avoid shadows, glare, or wet surfaces.
- Use hardness, streak, luster, grain size, and locality together; no single trait is enough for every specimen.
Where Spinel is found
Spinel is reported from multiple localities or geological settings. Exact locality should be verified from specimen provenance, maps, or field notes.
How much is Spinel worth?
| Entry-level specimen | $100 |
|---|---|
| Typical collector specimen | $500 |
| Premium specimen | $10000+ |
Value depends on size, condition, color, crystal quality, locality, rarity, preparation, and provenance. Treat this as educational guidance, not an appraisal.
Common uses
- Jewelry
- Collector specimens
Interesting facts
- The Black Prince's Ruby in the British Crown is actually a spinel
- Only recently recognized as a distinct gem, not ruby
- August birthstone (added in 2016)
Care & safety
Treat Spinel as a collector specimen unless hardness, cleavage, and fracture are confirmed.
Avoid inhaling dust. Do not cut, grind, or polish unknown specimens without eye protection and a properly rated respirator.
.jpg?width=320)
.jpg?width=320)