Historically marginalized by Ruby, Spinel’s fortunes beautifully changed when late-90s discoveries at Tanzania’s world-renowned Mahenge (pronounced: Ma-hen-gay) gem-fields, transformed an obscure collectors’ favorite into a contemporary jewelry classic. One of the world’s rarest gems, Tanzanian Red Spinel’s signature, saturated, all-natural crimsons and strawberries possess incredible brightness and purity, due to their single-refractivity and excellent transparency. While Mahenge remains one of Tanzania’s most active mining areas, since 2012 increasing demand coupled with sporadic availability has seen prices dramatically increase.
Hardness 8
Refractive Index 1.712 - 1.762
Relative Density 3.54 - 3.63
Enhancement None
Beauty
Although Spinel has an incredible color palette, classic Mahenge highly-transparent, saturated pure-reddish-hues are most prized. Colored by traces of chromium and iron similar to Ruby, Tanzanian Red Spinel’s high purity, saturation and transparency make it the quality-benchmark. This marketplace ideal covers noble-reds, vivid-pinkish-reds, and hot-reddish-pinks, in a highly-desirable range of medium to medium-dark saturations (strength of color) and tones (lightness or darkness of color). As pink and red are technically the same, only varying in saturation and tone, arguments over color and value occur. In 1989 the International Colored Gemstone Association (ICA) helped resolve these disputes, sensibly stating, “Pink is really just light red”.
While Spinel are classified as Type II gemstones by the Gemological Institute of America (GIA), meaning they typically occur with some minor inclusions that may be eye-visible, the standard is eye-clean, the highest quality clarity grade for colored gemstones as determined by the world’s leading gemological laboratories.
Deft lapidary that accentuates Spinel’s inherent brilliance is a critical value consideration. Tanzanian Red Spinel is optimally faceted by experienced lapidaries, who carefully orientate each crystal to maximize its colorful brilliance, maintaining a high-polish/luster, and attractive overall appearance (outline, profile, proportions, and shape). Perfect jewelry gemstones, Mahenge Spinel’s are typically ovals and rounds, with the ever-popular cushions more challenging to obtain.
With hues usually cleaner, brighter and purer than Corundum (Ruby & Sapphire) due to its single refractivity, Spinel is actually scarcer, yet surprisingly, more affordable; all things being equal, it will cost much-less than a Ruby or Sapphire of similar quality.
Spinel derives its name from either the Latin ‘spina’ (thorn), for its characteristic octahedral crystals or the Greek ‘spintharis’ (spark), in reference to its bright red hues. This is despite the fact that Spinel actually occurs in a plethora of colors, including black, blue, orange, pink, purple, and red. Occasionally, color change varieties are found, turning color from a light gray-blue in daylight to a light-purple under candlelight. Other Spinel prefix varieties, both historic and current, include; Almandine Spinel (violet), Balas Ruby (a historical name for Red Spinel originating from either Badakhshan in Tajikistan and/or the Balaksh region of Sri Lanka), Cobalt Spinel (resembling fine Sapphires, these exceptional Blue Spinel are traditionally from Sri Lanka and are colored by cobalt), Flame Spinel (orange-red), Gahnite (also Gahnospinel, a greenish or bluish, zinc-rich variety of Spinel), Noble Red Spinel (Ruby-red), and Rubicelle (yellow to orange). In Roman times, red stones were collectively called ‘carbunculus’, and in the 11th century, Marbode separated three types of carbuncles, corresponding to the three hues: Ruby from Burma (Myanmar), Red Spinel from Badakhshan, and Red Garnet. While Spinel was recognized as a separate gem species in 1587 and scientifically distinguishable from Ruby since 1783, it continued to be confused with Ruby until the 19th century. Both the legendary 352 carat ‘Timur Ruby’ and the 170 carat ‘Black Prince’s Ruby’ in the British Imperial state crown jewels in the Tower of London are in fact, Spinel. Confused due to the proximity of their deposits, similar hardness, and trace amounts of chromium, Spinel and Corundum (Ruby and Sapphire) are actually fairly easy to tell apart. Spinel is singly refractive, while Corundum is doubly refractive. As it is the ‘master of disguise’, Spinel has few direct historical references, but they have a bizarre association with alchemists and sorcerers. Spinel was once used by practitioners of the ‘Dark Arts’ to summon demons, and also used as amulets to protect them from fire. One tale even describes how this gem could be used to work against their masters. Those thought to possess supernatural powers were found guilty if they began to shake when approached with a Spinel wrapped in paper!
Rarity
Mined from alluvial deposits or directly from igneous host rocks, Spinel’s main sources include, Burma (Myanmar), Madagascar, Sri Lanka, Tajikistan, Tanzania, and Vietnam. Most notable are southcentral Tanzania’s Mahenge area, Tunduru in Tanzania’s remote southeast, and central Vietnam’s Luc Yen Region.
Tanzanian Red Spinel is from deposits discovered in 1989 near Mahenge, headquarters of the Ulanga District, in Tanzania’s Morogoro Region, with prominent Mahenge localities including, Chipa, Ipanko, Ketuti, Lukanda, Mayote, Mbarabanga, and Ruaha. Mahenge is situated within the Mozambique Belt, a band in the Earth’s crust extending from Antarctica, through East Africa, into the Arabian-Nubian Shield. Mahenge Spinel is found in marble, similarly to other Red Spinel deposits, namely, Mogok in Burma (Myanmar), Kasigau in Kenya, Ocua in Mozambique, Kul I Lal in Tajikistan, and Luc Yen in Vietnam. Formed under very high temperatures and pressures approximately 600 million years ago, Mahenge’s metamorphic rocks contain numerous primary gemstone deposits. Very resistant to weathering, Spinel is often found in alluvial deposits as its marble host-rock disintegrates.
While Tanzanian Spinel was first discovered in the late-80s at alluvial and marble-rock deposits in the Morogoro Region, near both Matombo and Mahenge, its underdeveloped market saw miners concentrate on Ruby until the late-90s. By the early 90s, Ruby mining’s decline in Morogoro saw miners move to Songea and Tunduru, where along with Rubies and Sapphires, they also ‘discovered’ Spinel, learning about its evolving market. Sapphires’ discovery at Ilakaka in 1998 saw the market move to Madagascar, and while some resumed mining Ruby, others focused on Spinel. By 2005 more Mahenge miners were working Spinel than Ruby, with around 400 people artisanally mining Spinel, not only the mineral-rich alluvial deposits, but also directly mining marble host-rock with hand tools. Not requiring complex machinery, Mahenge Spinel mining is relatively simple. Once extracted by hand, the raw crystals (rough) are graded, with quality determined by color, clarity and size, as usual. Given the rough’s high cost, yield is critical, with high-demand ensuring all grades are used. Mineral specimens aside, gemmy-qualities are typically faceted, with lower grades suitable for cabochons and beads.
Given its historic-confusion, Spinel undoubtedly contributed to Ruby’s timeless popularity and recognition, but remained largely unknown in the jewelry marketplace. In 2007 four massive Spinel crystals weighing 6 to 54 kilograms were found at Ipanko. Their interiors were opaque, but external portions were gem-quality, yielding an exceptional range of beautiful gemstones, weighing 10 to 50 carats. While Spinel has been known for centuries, Ruby dominated the marketplace until Mahenge change perceptions. Initially fuel by connoisseurs, famous jewelry designers and labels positioned Mahenge Spinel as a beautiful, precious, rare and valuable gemstone, igniting demand among global consumers. With mining markedly decreasing from 2012 – 2015, marketplace demand quickly overtook supply, seeing prices for fine-Spinel dramatically increase. While limited, sporadic hand-mining continues, mechanized mining was never viable at Mahenge.
Spinel is also always totally natural and unenhanced, accentuating its desirability, rarity, and value. This elite attribute not only appeals to industry professionals, but also to jewelers and connoisseurs around the globe.
Durability & Care
Tanzanian Red Spinel (Mohs’ Hardness: 8) is an excellent choice for everyday jewelry. Tanzanian Red Spinel should always be stored carefully to avoid scuffs and scratches. Clean with gentle soap and lukewarm water, scrubbing behind the gem with a very soft toothbrush as necessary. After cleaning, pat dry with a soft towel or chamois cloth.
Map Location
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