Identification guide · Precious Stones
How to Identify Ruby
Ruby is usually red, pinkish red, and purplish red with a adamantine luster and is transparent. It has a Mohs hardness of 9. It scratches glass, steel and even quartz; only harder gems will mark it. Its streak is white. It is most often confused with Sapphire, Spinel, and Diamond; the tests below separate them.
Ruby identification checklist
| Color | Red, Pinkish Red, Purplish Red | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Adamantine | 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 | 9 | 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 | None | |
| Fracture | Conchoidal | Broken surfaces show smooth, curved, shell-like scoops. |
| Specific gravity | 4 | Heavier than it looks (specific gravity about 4). |
| Crystal system | Trigonal |
Ruby look-alikes and how to tell them apart
Both sit near Mohs 9, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Ruby 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. Ruby vs Spinel →
Diamond is harder (Mohs 10) than Ruby (Mohs 9), so Diamond will scratch Ruby and not the other way round. It scratches glass, steel and even quartz; only harder gems will mark it. Ruby vs Diamond →
Both sit near Mohs 9, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Ruby vs Alexandrite →
Is my Ruby real?
- Hardness: real Ruby sits at Mohs 9. Glass imitations are about 5.5, so genuine Ruby 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 Ruby examples.
- Use hardness, streak, luster, grain size, and locality together; no single trait is enough for every specimen.
Ruby identification FAQ
How can you tell if a rock is Ruby?
Check the color (red, pinkish red, and purplish red), the adamantine luster, a Mohs hardness of 9 and a white streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Ruby?
Ruby has a Mohs hardness of 9. It scratches glass, steel and even quartz; only harder gems will mark it.
What is the difference between Ruby and Sapphire?
Ruby (Mohs 9, adamantine luster) and Sapphire (Mohs 9, adamantine luster) look alike, but hardness, streak and heft usually separate them. See the full Ruby vs Sapphire comparison for a side-by-side table.
How do I know if my Ruby is real?
Real Ruby 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 Ruby worth anything?
Entry-level Ruby specimens sell for around $1000, typical collector pieces about $10000, and premium examples $100000 or more depending on size, quality and locality.
What color is Ruby?
Ruby is most often red, pinkish red, and purplish red. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
