Ruby
Corundum var. Ruby · Precious Gemstone
Crystal System
Trigonal system, typically forming barrel-shaped, prismatic, or tabular crystals with basal pinacoids.
Mineral Group
Oxides group, hematite subgroup
Chemical Formula
Al2O3 (with trace amounts of Cr3+ substituting for Al3+)
Formation Process
Metamorphic and igneous processes. Specifically, regional or contact metamorphism of aluminum-rich clay-bearing limestones and marbles at high temperatures and pressures.
About This Crystal
The specimen is a beaded bracelet composed of faceted, spherical beads displaying a deep purplish-red to magenta coloration. The beads are translucent to opaque with a vitreous to sub-vitreous luster, featuring natural surface pitting, internal inclusions, and characteristic cloudiness typical of lower-grade or opaque ruby material.
Physical Characteristics
Color ranges from pinkish-red to deep purplish-red; white streak; no true cleavage, but exhibits parting along certain crystallographic planes; conchoidal to uneven fracture; specific gravity of approximately 3.99-4.10; brittle tenacity; displays red fluorescence under longwave UV light due to chromium content.
Optical Properties
Uniaxial negative with strong dichroism showing distinct purplish-red and yellowish-red hues when viewed from different angles; refractive index ranges from 1.762 to 1.770; birefringence is 0.008.
Hardness & Durability
Origin Region
Notable sources include Myanmar (Burma), Mozambique, Madagascar, Thailand, and Sri Lanka. Forms in metamorphic marbles and alluvial placer deposits.
Hardness & Durability
Mohs hardness of 9, making it extremely durable and second only to diamond; excellent resistance to scratching and general wear, though internal fractures or parting planes can make it susceptible to heavy impacts.
Care & Maintenance
Safe to clean with warm soapy water and a soft brush; ultrasonic and steam cleaners are generally safe for solid natural stones unless heavily fractured or glass-filled; store separately in a fabric-lined box to prevent it from scratching softer gemstones.
Rarity & Value
Common to Rare depending on quality. Opaque to translucent bead-grade material is relatively common and affordable, whereas transparent, untreated gem-grade Burmese rubies are extremely rare and valuable. Treatments such as heat treatment and fracture-filling with lead glass are very common for lower-grade commercial material.
Special Characteristics
May exhibit strong red fluorescence under ultraviolet light. Some specimens can display asterism (a six-rayed star effect) when cut as cabochons, caused by microscopic rutile needle inclusions.
Lore & History
Historically revered across ancient cultures including India, China, and Europe as a stone of nobility, passion, and protection. Often associated with the root chakra, traditional lore considers ruby to boost vitality, life force, and courage, though these are cultural beliefs rather than scientifically verified properties.