Ruby
Corundum var. Ruby · Precious Gemstone
Crystal System
Trigonal, typically forming barrel-shaped, prismatic, or tabular hexagonal crystals, often with tapered terminations
Mineral Group
Oxides
Chemical Formula
Al2O3 (with trace amounts of Cr3+ substituting for Al3+)
Formation Process
Metamorphic and igneous processes, often forming via regional or contact metamorphism of aluminum-rich limestones and marbles at high temperatures and pressures
About This Crystal
A vivid deep pinkish-red to crimson crystal specimen exhibiting a translucent to transparent nature with a sub-adamantine to vitreous luster. The crystal shows a distinct barrel-like or doubly-tapered habit with characteristic surface striations and a rich, saturated color distribution.
Physical Characteristics
Vivid purplish-red to red color; white streak; no true cleavage, instead exhibiting parting along specific planes; conchoidal to uneven fracture; specific gravity of approximately 4.00; brittle tenacity; strong red fluorescence under shortwave and longwave ultraviolet light.
Optical Properties
Uniaxial negative with a refractive index of 1.762-1.770; strong birefringence of 0.008; distinct dichroism showing purplish-red and yellowish-red from different crystallographic directions.
Hardness & Durability
Origin Region
Notable sources include Myanmar (Burma), Mozambique, Thailand, Madagascar, and Sri Lanka; typically found in marbles, basaltic terrains, and alluvial placers
Hardness & Durability
Mohs hardness of 9, making it extremely durable and second only to diamond; excellent toughness with no cleavage, making it highly suitable for everyday jewelry wear.
Care & Maintenance
Highly durable and resistant to most chemicals; safe to clean with warm soapy water, ultrasonic cleaners, and steam cleaners (unless heavily fractured or fracture-filled); store separately to prevent scratching softer gemstones.
Rarity & Value
Rare to extremely rare for fine-quality specimens; value is heavily driven by color saturation, clarity, carat weight, and geographic origin (such as classic Burmese origin); heat treatment and fracture-filling with lead glass are common commercial enhancements.
Special Characteristics
Strong red fluorescence under UV light due to chromium content; may exhibit asterism (star ruby) if fine rutile needles are present within the crystal structure.
Lore & History
Historically regarded as the 'King of Gems' across ancient cultures including India and Burma, where it was believed to protect warriors and bestow vitality. In modern metaphysical practices, it is associated with the root chakra, passion, life force, and courage, though these are traditional beliefs rather than scientific claims.