Identification guide · Organic Gems
How to Identify Pearl
Pearl is usually white, cream, and pink with a pearly luster and is opaque. It has a Mohs hardness of 3. A copper coin (Mohs 3.5) scratches it, but a fingernail does not. Its streak is white. It is most often confused with Aragonite, Serpentine, and Red Coral; the tests below separate them.
Pearl identification checklist
| Color | White, Cream, Pink, Black, Gold | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Pearly | Compare a fresh surface with glass and metal; this luster is softer than either. |
| Transparency | Opaque | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 3 | A copper coin (Mohs 3.5) scratches it, but a fingernail does not. |
| Streak | White | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | None | |
| Fracture | Uneven | |
| Specific gravity | 2.7 | Ordinary rock-like heft (specific gravity about 2.7), similar to quartz. |
| Crystal system | Orthorhombic |
Extra tests for Pearl
Acid test. Fizzes in vinegar or dilute hydrochloric acid because of its carbonate content.
Pearl look-alikes and how to tell them apart
Both sit near Mohs 3, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Pearl vs Aragonite →
Both sit near Mohs 3, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Pearl vs Serpentine →
Both sit near Mohs 3, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Pearl vs Red Coral →
Greenschist is harder (Mohs 4.5) than Pearl (Mohs 3), so Greenschist will scratch Pearl and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
Is my Pearl real?
- Hardness: real Pearl sits at Mohs 3. Glass imitations are about 5.5, so use a steel file and a known reference mineral rather than glass alone.
- 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 Pearl examples.
- Use hardness, streak, luster, grain size, and locality together; no single trait is enough for every specimen.
Pearl identification FAQ
How can you tell if a rock is Pearl?
Check the color (white, cream, pink, and black), the pearly luster, a Mohs hardness of 3 and a white streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Pearl?
Pearl has a Mohs hardness of 3. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
What is the difference between Pearl and Aragonite?
Pearl (Mohs 3, pearly luster) and Aragonite (Mohs 3.5–4, vitreous to resinous luster) look alike, but hardness, streak and heft usually separate them. See the full Pearl vs Aragonite comparison for a side-by-side table.
How do I know if my Pearl is real?
Real Pearl 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 Pearl worth anything?
Entry-level Pearl specimens sell for around $50, typical collector pieces about $500, and premium examples $100000 or more depending on size, quality and locality.
What color is Pearl?
Pearl is most often white, cream, pink, and black. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
