Identification guide · Semi-Precious Stones
How to Identify Spinel
Spinel is usually red, pink, and blue with a vitreous luster and is transparent. It has a Mohs hardness of 8. It scratches glass, steel and even quartz; only harder gems will mark it. Its streak is white. It is most often confused with Sapphire, Ruby, and Garnet; the tests below separate them.
Spinel identification checklist
| Color | Red, Pink, Blue, Purple, Orange, Black | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Vitreous | Fresh surfaces shine like glass; a dull surface usually means weathering, so chip or wet a corner. |
| Transparency | Transparent | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 8 | It scratches glass, steel and even quartz; only harder gems will mark it. |
| Streak | White | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Imperfect | |
| Fracture | Conchoidal | Broken surfaces show smooth, curved, shell-like scoops. |
| Specific gravity | 3.6 | Heavier than it looks (specific gravity about 3.6). |
| Crystal system | Cubic |
Extra tests for Spinel
Glass check. Spinel shares a glassy luster and conchoidal fracture with man-made glass. Glass sits near Mohs 5.5 and often contains round gas bubbles, so a hardness test and a hand lens separate them.
Spinel look-alikes and how to tell them apart
Sapphire is harder (Mohs 9) than Spinel (Mohs 8), so Sapphire will scratch Spinel and not the other way round. It scratches glass, steel and even quartz; only harder gems will mark it. Spinel vs Sapphire →
Ruby is harder (Mohs 9) than Spinel (Mohs 8), so Ruby will scratch Spinel and not the other way round. It scratches glass, steel and even quartz; only harder gems will mark it. Spinel vs Ruby →
Spinel is harder (Mohs 8) than Garnet (Mohs 7), so Spinel will scratch Garnet and not the other way round. It scratches glass and a steel knife and cannot be scratched by a steel file. Spinel vs Garnet →
Both sit near Mohs 8, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Spinel vs Topaz →
Is my Spinel real?
- Hardness: real Spinel sits at Mohs 8. Glass imitations are about 5.5, so genuine Spinel scratches glass while a glass fake cannot.
- Bubbles: round gas bubbles under a 10x loupe mean glass or resin, never a natural stone.
- Color: dyed material concentrates color in cracks and pores; look for pigment collecting at the edges of fractures.
- Temperature: natural crystals feel cool and take longer to warm in your hand than plastic or resin.
Field tips
- Check whether the specimen's color and texture match typical Spinel examples.
- Use hardness, streak, luster, grain size, and locality together; no single trait is enough for every specimen.
Spinel identification FAQ
How can you tell if a rock is Spinel?
Check the color (red, pink, blue, and purple), the vitreous luster, a Mohs hardness of 8 and a white streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Spinel?
Spinel has a Mohs hardness of 8. It scratches glass, steel and even quartz; only harder gems will mark it.
What is the difference between Spinel and Sapphire?
Spinel (Mohs 8, vitreous luster) and Sapphire (Mohs 9, adamantine luster) look alike, but hardness, streak and heft usually separate them. See the full Spinel vs Sapphire comparison for a side-by-side table.
How do I know if my Spinel is real?
Real Spinel matches the hardness listed above, shows no round gas bubbles under magnification, and does not concentrate dye in cracks. Glass and resin fakes fail at least one of those checks.
Is Spinel worth anything?
Entry-level Spinel specimens sell for around $100, typical collector pieces about $500, and premium examples $10000 or more depending on size, quality and locality.
What color is Spinel?
Spinel is most often red, pink, blue, and purple. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
