Pearl
Biogenic Calcium Carbonate (Aragonite/Calcite) var. Pearl · Organic Gemstone
Crystal System
Orthorhombic (as microcrystalline aragonite laths) and Hexagonal (calcite)
Mineral Group
Carbonates
Chemical Formula
CaCO3 with organic conchiolin and water
Formation Process
Biogenic: Formed inside a mollusk (oyster or mussel) as a defense mechanism against an irritant
About This Crystal
Spheroid gem with a smooth, pearly luster. This specimen appears as a white Akoya-style pearl with a high-gloss vitreous-to-pearly finish and visible orient (iridescence)
Physical Characteristics
Color: White to cream; Streak: White; Cleavage: None; Fracture: Uneven; Specific Gravity: 2.60-2.85; Fluorescence: Usually weak (blue, yellow, or green)
Optical Properties
Refractive Index: 1.52-1.66; Birefringence: 0.156; Exhibits 'orient' (iridescence) due to light diffraction and interference on nacre layers
Hardness & Durability
Origin Region
Persian Gulf, South Sea, Japan (Akoya), and freshwater rivers in China and the US
Hardness & Durability
Mohs Hardness: 2.5-4.5; Very soft and prone to scratching; vulnerable to acids and extreme dryness
Care & Maintenance
Clean with a soft damp cloth only. Avoid ultrasonic cleaners, steam, perfume, hairspray, and acids. Store separately in a soft pouch
Rarity & Value
Common (Cultured) to Extremely Rare (Natural). Value depends on roundness, luster, surface quality, size, and matching
Special Characteristics
Orient (iridescence), overtone colors, and surface texture resulting from the overlapping of microscopic aragonite platelets
Lore & History
Historically known as 'tears of the gods'; symbol of purity and wisdom. Used as currency in ancient times and traditionally associated with the Moon and June birthdays