Pearl
Calcium Carbonate (biogenic) - Aragonite/Calcite · Organic Gemstone
Crystal System
Orthorhombic (as microcrystalline aragonite) in concentric layers
Mineral Group
Carbonates (Biogenic)
Chemical Formula
CaCO3 (with organic conchiolin and water)
Formation Process
Biogenic: Secreted by mollusks (oysters/mussels) as concentric layers of nacre around an irritant
About This Crystal
Smooth, spherical to baroque round shape with a distinctive pearly luster and iridescent 'orient'. Color is creamy white to silvery-white with subtle overtones.
Physical Characteristics
Color: White to cream; Streak: White; Luster: Pearly; Specific Gravity: 2.60-2.85; Fluorescence: Usually inert to weak bluish-white
Optical Properties
Refractive Index: 1.52-1.66; Birefringence: 0.156; Optical Phenomenon: Orient (iridescence caused by light interference/diffraction in nacre layers)
Hardness & Durability
Origin Region
Japan (Akoya), Australia and Indonesia (South Sea), French Polynesia (Tahiti), China (Freshwater)
Hardness & Durability
Mohs Hardness: 2.5–4.5; Toughness: Very high (resistant to crushing); Stability: Sensitive to acids, heat, and dehydration
Care & Maintenance
Avoid chemicals (perfumes, hairspray), ultrasonic cleaners, and steam. Clean with a soft damp cloth. Store separately to avoid scratching.
Rarity & Value
Common (cultured) to Extremely Rare (natural). Value depends on luster, surface quality, shape, size, and matching in strands.
Special Characteristics
Orient (iridescence), overtone colors, and 'tooth test' texture (gritty feel against teeth due to aragonite crystal edges)
Lore & History
Historically known as the 'Queen of Gems'. Associated with purity, innocence, and moonlight. Used in royal jewelry across ancient Rome, Egypt, and China.