Spinel
The stone in the crown that everyone called ruby.
- Family
- Spinel
- Formula
- MgAl₂O₄
- Mohs
- 8
- System
- Cubic
Drag to turn
Science
Spinel forms in the same marbles as ruby and was not separated from it until 1783. It is singly refractive, so its colour is even and its crystals are perfect octahedra. Unlike ruby it is almost never treated, which has driven its revival among collectors.
- Mineral
- Spinel
- Formula
- MgAl₂O₄
- Crystal system
- Cubic
- Mohs hardness
- 8
- Specific gravity
- 3.60
- Refractive index
- 1.718
- Lustre
- Vitreous
- Colours
- Red, Pink, Blue, Grey, Purple
- Birthstone
- August
Composition
MgAl₂O₄. Made of Magnesium, Aluminium, Oxygen, with trace Chromium, Iron, Cobalt responsible for colour.
Origin
- MyanmarMogok
- TanzaniaMahenge, neon pink
- Sri Lanka
- VietnamLuc Yen, cobalt blue
- TajikistanKuh-i-Lal, historic
- Madagascar
Filled dots are primary sources
Rarity
Uncommon; fine red and cobalt-blue spinel are rarer than ruby and sapphire of the same colour but still priced below them.
- 1 Abundant
- 2 Common
- 3 Uncommon
- 4 Rare
- 5 Exceptional
Hardness
Spinel sits at 8 on the Mohs scale. It will scratch glass and holds a polish in daily wear.
Energy
Associations from crystal-healing tradition, recorded here as folklore. They are not medical claims.
Chakras
- Root
- Heart
Element
- Fire
Zodiac
- Aries
- Sagittarius
Planets
- Mars
Properties
- Revitalisation
- Hope
- Renewal
- Perseverance
Lore
The Black Prince's Ruby in the British Imperial State Crown, the Timur Ruby, and the 398-carat stone in the Russian imperial crown are all spinel from Kuh-i-Lal in the Pamirs.
Added to the list of August birthstones in 2016, its first official recognition.
- OctahedraCubic crystals so sharp Burmese miners call them 'nat thwe', spirit-polished.
- SyntheticCheap synthetic spinel has imitated aquamarine and zircon since the 1920s.