Ruby
Corundum var. Ruby · Precious Gemstone
Crystal System
Trigonal - Hexagonal scalenohedral; typically occurs as dipyramidal or tabular prismatic crystals
Mineral Group
Oxides (Hematite group)
Chemical Formula
Al2O3 with Chromium (Cr3+) trace elements
Formation Process
Metamorphic or Magmatic; forms under high temperature and high pressure conditions in aluminum-rich, silica-poor environments
About This Crystal
Vivid 'pigeon blood' to deep reddish-pink transparent gems featuring vitreous luster. These specimens appear as small round-cut faceted stones in a metal setting, showing high clarity and rich color saturation.
Physical Characteristics
Color: Red; Streak: White; Cleavage: None (has parting); Fracture: Conchoidal to uneven; Specific Gravity: 3.97-4.05; Strong red fluorescence under Long-Wave UV.
Optical Properties
Refractive Index: 1.762-1.770; Birefringence: 0.008; Strongly pleochroic (purplish-red to orangey-red); Singly refractive (uniaxial negative).
Hardness & Durability
Origin Region
Myanmar (Burma), Mozambique, Thailand, and Sri Lanka; found in metamorphic marbles or basaltic deposits
Hardness & Durability
Mohs Hardness: 9; Excellent toughness and stability; highly resistant to scratching and chemical erosion.
Care & Maintenance
Clean with warm soapy water or ultrasonic cleaners (if no fractures). Store separately from softer stones. Avoid hydrofluoric acid.
Rarity & Value
Very Rare (especially in high clarity); value determined by '4 Cs' with color (saturation and hue) being paramount; heat treatment is common to enhance clarity.
Special Characteristics
Strong red fluorescence due to chromium content; potential for silk (rutile) inclusions which often verify natural origin.
Lore & History
Historically known as the 'King of Precious Stones' (Ratnaraj); symbol of passion, protection, and prosperity. Associated with the Root Chakra and used by royalty throughout history to denote power.