Identification guide · Precious Stones
How to Identify Diamond
Diamond is usually colorless, yellow, and blue with a adamantine luster and is transparent. It has a Mohs hardness of 10. It scratches glass, steel and even quartz; only harder gems will mark it. Its streak is none. It is most often confused with Sapphire, Corundum, and Kimberlite; the tests below separate them.
Diamond identification checklist
| Color | Colorless, Yellow, Blue, Pink, Black | 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 | 10 | It scratches glass, steel and even quartz; only harder gems will mark it. |
| Streak | None | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Perfect octahedral | |
| Fracture | Conchoidal | Broken surfaces show smooth, curved, shell-like scoops. |
| Specific gravity | 3.52 | Heavier than it looks (specific gravity about 3.52). |
| Crystal system | Cubic |
Diamond look-alikes and how to tell them apart
Diamond is harder (Mohs 10) than Sapphire (Mohs 9), so Diamond will scratch Sapphire and not the other way round. It scratches glass, steel and even quartz; only harder gems will mark it. Diamond vs Sapphire →
Diamond is harder (Mohs 10) than Corundum (Mohs 9), so Diamond will scratch Corundum and not the other way round. It scratches glass, steel and even quartz; only harder gems will mark it. Diamond vs Corundum →
Diamond is harder (Mohs 10) than Kimberlite (Mohs 5–6.5), so Diamond will scratch Kimberlite and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Diamond vs Kimberlite →
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. Diamond vs Ruby →
Is my Diamond real?
- Hardness: real Diamond sits at Mohs 10. Glass imitations are about 5.5, so genuine Diamond 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 Diamond examples.
- Use hardness, streak, luster, grain size, and locality together; no single trait is enough for every specimen.
Diamond identification FAQ
How can you tell if a rock is Diamond?
Check the color (colorless, yellow, blue, and pink), the adamantine luster, a Mohs hardness of 10 and a none streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Diamond?
Diamond has a Mohs hardness of 10. It scratches glass, steel and even quartz; only harder gems will mark it.
What is the difference between Diamond and Sapphire?
Diamond (Mohs 10, adamantine luster) and Sapphire (Mohs 9, adamantine luster) look alike, but hardness, streak and heft usually separate them. See the full Diamond vs Sapphire comparison for a side-by-side table.
How do I know if my Diamond is real?
Real Diamond 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 Diamond worth anything?
Entry-level Diamond specimens sell for around $1000, typical collector pieces about $5000, and premium examples $100000 or more depending on size, quality and locality.
What color is Diamond?
Diamond is most often colorless, yellow, blue, and pink. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
