Among August’s three official birthstones, spinel offers the most surprising burst of colors. And within the spinel family, the vivid neon-pink gems from Tanzania’s Mahenge region are in a class of their own. Discovered in 2007, Mahenge spinel is prized for its intensely saturated color, exceptional clarity and an almost magical quality that makes the finest stones seem to glow from within.
The remarkable material surged onto the international gem scene when artisanal miners working near Mahenge discovered enormous spinel crystals in a local farmer’s field.
One of the largest rough specimens reportedly weighed about 52 kilograms (114 pounds). Although much of the material inside the giant crystals was opaque, their edges and surrounding pockets yielded exceptionally transparent, vividly colored gem rough.
When expertly cut, some of these stones displayed a spectacular neon quality. The secret is chromium.
Trace amounts of chromium give Mahenge spinel its pink-to-red body color. The element can also cause strong fluorescence, while the unusually low iron content of some Mahenge material allows that effect to shine through. The result is a gemstone that can appear almost backlit, as if a tiny source of light were glowing beneath its surface.
That eye-catching color helped transform spinel's reputation. For centuries, spinel was known primarily as the “great imposter” because red spinels were routinely mistaken for rubies. Several legendary “rubies” in royal collections — including the 170-carat Black Prince’s Ruby in the British Crown Jewels — are actually spinels.
Spinel finally received its own place in the spotlight in 2016, when the American Gem Trade Association and Jewelers of America added it to the official August birthstone list alongside peridot and sardonyx. The addition gave August celebrants a colorful alternative while recognizing a gemstone whose identity had long been overshadowed by ruby.
And spinel is far from being a one-color wonder. Although deep red and neon pink are among the most coveted varieties, natural spinel can also be found in shades of peach, orange, pink, purple, blue, green and even colorless.
It is also a practical choice for jewelry. With a Mohs hardness of 8, spinel is harder than many popular colored gemstones and is well suited to rings, earrings, pendants and other jewelry worn regularly.
Credit: Conceptual image by The Jeweler Blog using aichatapp.ai.