Gem Focus – August 2019

Posted on August 8, 2019 by The Gemworld Staff

Spinel, the most misidentified and under appreciated gem in history, is gaining back its glory.

Most gem professionals are made to believe that if it wasn’t for modern gemology, we wouldn’t know the difference between red spinel and ruby. This misconception is rooted in the tale of the Black Prince’s Ruby. However, eastern cultures have revered all red stones for their beauty and used specific names for spinel, ruby and garnet for millennia. Their popularity and trading were defined by their own merits.

The confusion of spinel’s identification in the recent century caused damage to its reputation. Synthetic production hasn’t helped either. Unfortunately, the general public would eventually come to regard spinel as a simulant. But thankfully there has been a strong reversal of that notion. In recent years, the popularity of spinel has gained considerable recognition in the global gem market as a beautiful, rare gemstone. Consumers are more aware of the beauty and rarity of fine quality spinel and appreciate the gem for its own merit, whereas previously it was often marketed as a more affordable alternative to ruby or sapphire. Despite the few heat-treated samples that have been reported in trade journals, the vast majority of spinel on the market are believed to be natural. Natural spinel remains one of the more affordable of the fine gems, especially compared to untreated corundum.

Spinel is a solid solution series mineral. Gem quality spinel occur in a range of hues with reds, pinks to lavenders and blues being particularly important to the trade. Transparent material is expected. Other spinel species are better known for industrial use such as chromite and magnetite. During the past few years, due to increasing popularity of black gems, black spinel species have been fashioned as gems too. However, it must be noted that the refractive index of black spinels are much higher than of gem spinels and read OTL on the refractometer.

Mogok, Burma is known to be the oldest source of pink and red spinel. Namya (Namyazeik or Nanyazeik, near Kachin State) is another, newer source in Burma. Other notable sources include Tajikistan, Vietnam, Tanzania, Sri Lanka and Madagascar, which produce spinel in various colors and qualities. A more recent discovery, the Mahenge deposit (in Tanzania), produced some sensational material and is credited by some for generating more excitement and awareness of spinels. The color intensity associated with the Mahenge material fundamentally changed the price structure and popularity of spinel. Beautifully saturated pink to red colors of the Mahenge material captured the attention of mainstream dealers, thus shattering spinel’s reputation as collection stone.

Blue spinels vary in tone and saturation due to their cobalt content as the chromophore. The rarest and the most revered example is the bright blue spinel from Vietnam. Vibrant cobalt blue commands several times more per carat price compared to other blue to lavender spinels.

Recently, another color of spinel began appearing in the market. Various tones of transparent gray spinels have been offered to buyers and celebrated by collectors. Gray is a very desaturated blue and violet, so these stones come with some color flashes. Dealers report smaller sizes of 2 to 4 ct. as common, and anything over 7 ct. is very unusual. Gray spinels typically have eye visible inclusions but clean stones are also available.  Burma and Tanzania are reported to be main locations for this unusual color of spinel.

Caption: Carved spinel from Mahenge, Tanzania. Courtesy of Pala International. Photo by Mia Dixon.

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