Semi-Precious Stones · uncommon
Spinel
Spinel was historically mistaken for ruby and sapphire. The 'Black Prince's Ruby' in the British Crown Jewels is actually a spinel.
Also known as: august birthstone, balas ruby, crown jewel gem.
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.
Full Spinel identification guide: checklist, home tests and look-alikes →
Spinel vs similar stones
Not sure it isn't something else? Side-by-side comparisons with the stones most often confused with Spinel.
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.
Spinel FAQ
What is Spinel?
Spinel was historically mistaken for ruby and sapphire. The 'Black Prince's Ruby' in the British Crown Jewels is actually a spinel.
How much is Spinel worth?
Entry-level Spinel specimens sell for around $100, a typical collector specimen for about $500, and premium pieces for $10000 or more. Value depends on size, condition, color, crystal quality, locality, rarity, preparation, and provenance. Treat this as educational guidance, not an appraisal.
How hard is Spinel?
Spinel has a Mohs hardness of 8. It scratches glass, steel and even quartz; only harder gems will mark it.
Where is Spinel found?
Notable sources of Spinel include Myanmar, Sri Lanka, Vietnam, Tanzania, and Tajikistan. Forms in metamorphic and some igneous rocks from aluminum and magnesium-rich parent rocks..
What is Spinel used for?
Spinel is used for jewelry and collector specimens.
