Tanzanian Pink Spinel

When it’s red, it does look a lot like ruby. When it’s pink, it looks a lot like pink sapphire. Luster and polish are similar, with spinel’s hardness scoring an 8, corundum a 9. Color for both ruby and pink/red spinel is created by the same coloring agent, giving them both the exact same hue. Making it even more confusing, spinel and corundum are often unearthed in the same region as their chemistry is so similar. (Corundum is aluminum oxide; spinel is a magnesium aluminum oxide.)

This is why red spinel has been called ruby for centuries. In fact, the most famous spinel in the world is called the Black Prince’s Ruby. (See “Jewel of the Month,” JCK, March 2002, p. 73.) Even today few people really salute the name spinel. Could this new find of Tanzanian pinks change that?

Color. Like sapphire, spinel occurs in a rainbow of colors. In its purest state, they’re colorless. By adding trace elements, they change colors. Adding chromium results in pink and red.

Tanzanian spinel colors range from purplish pink to pink to pink-orange/orange-pink (padparadscha-like). Rarely, one can find red or brownish red.

Country of Origin. Today, the finest spinels are found in Burma and Sri Lanka. You can now add Tanzania to the list.

When the Tanzanian pinks were unearthed, there was a rush to see how they compared to Burmese and Sri Lankan stones. And they do, quite well. While not as saturated as the best reds, these pinks have a great range of hue and variation of tone. “These spinels can be quite vivid,” says Eric Saul, of SWALA Gem Traders, and International Colored Gemstone Association ambassador to Tanzania.

Values for pinks range from $1,000 to $3,000 per carat. Vivid reds can range up to $10,000 a carat!

The Rodney Dangerfield of Gems. Spinels have been mislabeled and synthesized, and have been claimed to be the third-best red and pink stone, exceeded only by diamond and corundum, yet it has never been given a place on the birthstone list. In fact, it is the synthetic spinel that is set into the high-school and college class rings only to resemble the true birthstones of ruby, tourmaline, topaz, and zircon.

Mining Locale. Joseph Gil of Akiva Gil, New York, has been acquiring and cutting pink spinel from Tanzania now for the past several years. The most important mine site, located near Mahenge in the lower half of the Morogoro region, is closer to the corundum deposits of Tunduru and Songea in the south, rather than the tanzanite deposits near Arusha in the north.

Found in mostly smaller sizes, it is very rare to find a piece of rough 3 to 4 cts. and up, “although a few very large stones have been sold this past year,” says Saul. This is important since, as with most color gems, average recovery from the rough is around 15 to 20 percent. With approximately 20 percent of the rough inclusion clean, the majority will be cut en cabochon.