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History & Introduction


Spinel as a gemstone is hard vitreous magnesium aluminum oxide that has been used as a gemstone for centuries. In the past the beauty of spinel because it was mistook by sapphire and ruby. However, spinel is identified as a gemstone that is worthy of appreciation in its own right. Spinel is found in a wide variety of colors, such as rose pink to rich red; lavender to deep violet; light to deep blue, brown, orange, yellow, and black.

Spinel got its name either from the Latin word, "spina" that means thorn because of the pointed crystal form, or the Greek word for "spark", related to its bright color. Spinel is in fact mined for centuries and one of the most famous historical spinel gemstones is known as "the Black Prince's Ruby". Alike the name, this gemstone is in red color, which was thought to be a ruby. Edward, Prince of Wales in 1367 acquired the "Black Prince's Ruby."

Recognize - Spinel is mainly like the other gemstones, such as ruby and sapphire. But, the difference in spinel from other gemstones is due to octahedral crystal structure and single refraction. Additionally, spinel has a lower hardness than ruby and sapphire.

Availability - Spinel comes along with ruby and sapphire, and important deposits have been found in Myanmar (Burma), Cambodia, Thailand and Sri Lanka (Ceylon). Other locations where spinel deposits found are Australia, Afghanistan, Brazil, Madagascar, Nepal, Tanzania, Nigeria, Tadzhikistan, and USA.

Usages - Spinel is considered to be a rare mineral, and because of the qualities and color it is well substituted as a gemstone. It is cut in whatever gemstone cuts available, mainly in round and oval cuts, although it is surprisingly not used for jewelry purposes so much.

Buying Guide

Color - The most demanding spinel gemstones are intense red, followed by cobalt blue, bright pink and bright orange. Paler colors such as lavender tend to be more affordable. Other colors are black, mauve, greenish-blue, greyish, pale-pink, violet-blue, yellow and brown.

Clarity and Lustre - Good quality spinel gemstones should have no visible additions. The additions typically lower the value of spinel gemstones. In fact, desirable enclosures can result in asterism (the star effect). Presences in spinel resembles to its octahedral crystal structure or a human fingerprint. Spinel has a vitreous luster.

Cut and Shape - Spinel can be seen in faceted shapes such as rounds, octagons, squares, trillions and fancy shapes, such as pears, ovals and cushions. Vividly colored spinel gemstones are rare in sizes over 5 carats. Translucent to opaque stones are frequently cut en cabochon. There are few star spinel cut in en cabochon to display the asterism.

Treatment - Naturally found spinel is not usually treated but, synthetic spinel is commonly produced because it can appear similar to a variety of gemstone types. Mainly the synthetic spinel is separated from natural spinel by the use of a magnet. Due to the iron content natural spinel shows a weak to moderate response. Some light-colored and orange spinel is colored by chromium, which causes it to be diamagnetic (repelled by a magnet). In addition to its natural spinel presents an octahedral crystal structure. Spinel available naturally are also reputable gem traders declare products as natural or synthetic.

Gemological Characteristics:

Chemical Formula MgAl2O4 Magnesium aluminium oxide
Crystal Structure Cubic; octahedron, twins, rhombic dodecahedron
Colour Red, orange, yellow, brown, blue, violet, purple, green, black
Hardness 7.5-8
Refractive Index 1.712 to 1.762
Density 3.54 to 3.63
Cleavage Indistinct
Transparency Transparent to opaque
Double Refraction or Birefringence None
Lustre Vitreous
Fluorescence Red spinel, strong: red. Blue spinel, weak: reddish, green
Crystal Forms and Aggregates Spinel occurs in octahedral crystals, often in perfectly shaped octahedrons. Crystals often have parallel layer growths or heavy etchings. Crystals can also be distorted as well as have complex faces. Crystal clusters and twinned octahedrons are very common, especially spinel twinning, which this mineral is famous for. An interesting habit occasionally observed in Spinel is the macle, which is a triangular form of two flattened crystal twins. Spinel also occurs grainy and as rounded, waterworn pebbles.
Fracture Conchoidal
Tenacity Brittle
Rock Type Igneous, Metamorphic
Popularity (1-4) 1
Prevalence (1-3) 3
Demand (1-3) 1

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