* spinel gemstone
Spinel: identification, value, and how to spot a fake
Long mistaken for ruby (the Black Prince's Ruby and Timur Ruby in the British Crown Jewels are both spinels). Untreated by definition. Burmese 'Mahenge' pink spinel commands extreme premiums.
Published May 30, 2026
Quick facts
- Mineral family
- spinel
- Chemical formula
- MgAl2O4
- Mohs hardness
- 7.5–8
- Refractive index
- 1.712–1.762
- Specific gravity
- 3.58–3.61
- Crystal system
- cubic
- Luster
- vitreous
- Dispersion
- 0.02
- Birthstone month
- August
Colors
Spinel is found in red, pink, blue, purple, black, colorless. The body color, its saturation, and how evenly it spreads through the stone are among the strongest drivers of value.
How to tell real from imitation
No single test settles it, but a few grounded checks quickly narrow things down for Spinel. Hardness, brilliance, and the list of stones it is commonly confused with all give you something concrete to look for.
- Scratch resistance: genuine Spinel sits at Mohs 7.5–8, so it should resist scratching from softer materials — a stone that mars far too easily is suspect.
- Brilliance & luster: Spinel shows a vitreous luster and a refractive index of 1.712–1.762; imitations often look glassier or flatter under the same light.
- Density: a real Spinel has a specific gravity near 3.58–3.61, so it feels heavier or lighter in the hand than many look-alikes of the same size.
- Commonly imitated by: ruby, synthetic spinel. If a deal looks too good, suspect one of these substitutes first.
- Fast first read: photograph the stone in the Jewelry Identifier app to estimate the gemstone and its likely value range, then confirm anything important with a gemological lab.
Common treatments
- none typically (untreated, exceptional in the trade)
Treatments are routine for many Spinel stones, but they materially affect value and should always be disclosed — an untreated, lab-certified stone commands a clear premium over a treated one.
What to know about Spinel
Long mistaken for ruby (the Black Prince's Ruby and Timur Ruby in the British Crown Jewels are both spinels). Untreated by definition. Burmese 'Mahenge' pink spinel commands extreme premiums.
Sources
* Frequently asked
FAQ
- Q. Is Spinel hard enough for everyday rings?
- A. Mostly. At a Mohs hardness of 7.5–8, Spinel stands up to routine wear, though sharp knocks and abrasive dust can still mar it over years of daily use.
- Q. How can I tell Spinel from ruby?
- A. Spinel and ruby can look alike to the naked eye, but they differ in measurable properties — refractive index (1.712–1.762 for Spinel), specific gravity (3.58–3.61), and hardness (Mohs 7.5–8). A gemologist confirms the distinction with a refractometer and loupe; the Jewelry Identifier app gives a fast first read from a photo.
- Q. Does Spinel come in colors other than red?
- A. Yes. Spinel occurs in red, pink, blue, purple, black, colorless. Color is driven by trace elements and treatment history, and it is one of the biggest factors in a stone's value.
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