Ruby
Corundum var. Ruby · Precious Gemstone
Crystal System
Trigonal, typically forming barrel-shaped, prismatic, or tabular hexagonal crystals
Mineral Group
Oxides
Chemical Formula
Al2O3 with trace amounts of Chromium (Cr3+)
Formation Process
Metamorphic formation, typically in aluminum-rich marbles under high temperatures and pressures where silica is deficient
About This Crystal
A small, polished or naturally rounded cabochon-like gemstone specimen exhibiting a vivid purplish-red to pinkish-red coloration with vitreous to sub-adamantine luster and translucent to semi-transparent clarity
Physical Characteristics
Deep red body color, white streak, no true cleavage but exhibits parting on rhombohedral planes, conchoidal to uneven fracture, specific gravity of approximately 4.00, brittle tenacity, and strong red fluorescence under longwave UV light
Optical Properties
Uniaxial negative with a high refractive index of 1.762-1.770, strong dichroism showing purplish-red and orangey-red from different angles, and high luster
Hardness & Durability
Origin Region
Mogok Valley in Myanmar (Burma), Mozambique, Madagascar, Thailand, and Vietnam; forms in marbles and metamorphic terrains
Hardness & Durability
Mohs hardness of 9, making it extremely durable and second only to diamond, with excellent toughness and high resistance to scratching and chemical attack
Care & Maintenance
Safe to clean with warm soapy water, ultrasonic cleaners, and steam cleaners unless heavily fractured or glass-filled; store separately from softer gems to prevent scratching
Rarity & Value
Rare to very rare for high-quality unheated stones; value is determined by color saturation (pigeon's blood red being most valuable), clarity, cut, and carat weight; treatments such as heat enhancement and fracture filling are common
Special Characteristics
Strong red fluorescence under ultraviolet light due to chromium content, and occasional asterism (six-rayed star effect) when rutile needles are present
Lore & History
Historically revered as the 'King of Gems' in ancient cultures, symbolizing passion, protection, wealth, and vitality; traditionally associated with the root chakra in modern crystal healing practices