PEARL
Pearl
A biogenic gem formed by mollusks
A gem produced through biological processes. Properties vary with the mollusk and freshwater or saltwater environment.
GEM PROFILE
Basic properties
- Mineral or material
- A biogenic gem formed by mollusks
- Main chemical composition
- Mainly CaCO₃ and organic material
- Crystal & structure
- Layers of microcrystals and organic material
Nacre consists primarily of fine aragonite crystals and organic material. Natural pearls and cultured pearls are distinguished.
- Typical colors
- White, cream, golden, pink, gray, dark colors and more
- Mohs hardness
- 2.5–3
A measure of scratch resistance, distinct from resistance to impact or breakage.
About hardness and durability - Representative sources
Examples of known sources. Determining the origin of an individual stone requires examination and comparison with reference material.
- Common cutting styles
- Normally used in their own shapes without cutting, including round and baroque forms.
Explore cutting styles
LOOK A LITTLE CLOSER
What to observe
Observe luster, surface, shape and color. Cultured pearls are pearls, distinct from glass or plastic imitations.
TREATMENT & CARE
Treatments & care
Treatments & identification
Bleaching, dyeing, irradiation and other processes may be used. Check the pearl's type and any treatment information.
Everyday care
Wipe away perspiration with a soft cloth after wearing. Avoid acids, cosmetics, ultrasonic cleaning and steam, and store separately from harder gems.
Cleaning depends on treatment, inclusions and mounting. If a stone's condition is unknown, ask your jeweler or a gem specialist before cleaning.
READING & REFERENCES
References
Public sources for learning about this gemstone's general properties.
This dictionary provides general educational information. Values are representative and do not identify or grade an individual stone. Locality examples include historical deposits.
Sources checked: October 19, 2026