Spinel
buying guide

A short history of mistaken identitythe crown jewel that was not a ruby

For five hundred years the most famous red gemstone in England has been a lie. The Black Prince’s Ruby in the Imperial State Crown is not a ruby. It is a spinel, and it fooled everyone until chemistry caught up with the crown jewels.

It was an honest mistake. Fine red spinel and fine ruby grow in the same marble, come out of the same gravels, and carry the same chromium fire. The great courts of Europe and Persia treasured their balas rubies for centuries without knowing they were a different species altogether.

Spinel is magnesium aluminate, its own mineral with its own habits. It forms in clean octahedral crystals, takes a glassy polish, and sits at 8 on the Mohs scale, hard enough for every day of a long life.

For most of the modern era that history worked against it. Spinel was priced as the also ran, the stone you bought when ruby was out of reach. Collectors quietly disagreed, and over the last twenty years the market has come around to what the crowns knew all along. It was never the understudy.

The colors of spinelred, pink, lavender, gray

Red comes first, because red is rarest. Chromium gives fine red spinel the same engine that drives ruby, and a top red spinel today is genuinely harder to find than a comparable ruby. Ours run from open cherry reds to deep stoplight color.

Pink is where spinel earns its modern reputation. The Mahenge deposit in Tanzania announced itself in 2007 with neon pinks that glow without any treatment at all, and the trade has chased them since. Lavender, violet, and purple stones deliver the same clean crystal for far less money.

Then there is gray. Quiet, steely, slightly silvered, gray spinel has become the connoisseur pick for modern engagement rings, and we sell more of it every year. How color is judged across all of these follows the same logic as any colored gemstone, covered in our grading guide.

Cobalt blue, the rare exceptionwhy one blue costs ten times the other

One blue stands apart. Most blue spinel is colored by iron, pleasant and steely and fairly priced. A small fraction is colored by cobalt, and cobalt blue spinel is electric, a saturated blue that seems lit from inside.

The benchmark cobalt material comes from Luc Yen in northern Vietnam, in sizes that rarely clear a carat clean. Prices follow. A true cobalt blue can cost ten times its iron colored cousin, and the difference is invisible on a price tag without proof.

Proof is the point. The word cobalt should come with a laboratory report that says so, because the premium rides entirely on that one element. Our certificate guide walks through exactly what those reports establish.

Where spinel comes fromBurma, Tanzania, Vietnam, Sri Lanka

Burma remains the storied source. The Mogok valley that made ruby famous produces the classic red and hot pink spinels, including the vivid material old dealers call Jedi, stones with no dark mask at all.

Tanzania carries the modern flag. Mahenge pinks set the market alight, and Tunduru adds a wide palette of colors. Sri Lanka has produced spinel for as long as it has produced sapphire, in blues, violets, and grays.

Vietnam holds the cobalt seam, and Tajikistan holds the history. The Badakhshan mines on the old silk routes supplied the great balas rubies of the medieval courts, including, almost certainly, the one in the English crown.

Treatment, barelyuntreated as the rule, not the premium

Here is the quietest selling point in the gem trade: spinel is almost never treated. There is no routine heating as with sapphire, no oiling as with emerald. The color you see is the color the ground made, as a rule rather than a premium.

The exceptions are knowable. A little Tanzanian material has been gently heated in recent years, and any treatment belongs on the receipt. Lab grown spinel also exists and has for a century, the blue stones in old class rings are usually synthetic spinel, so buy natural spinel from someone who states it plainly.

Durability needs no caveats. At 8 on the Mohs scale, spinel wears as confidently as sapphire and asks for nothing special. Soap, water, done.

Our position is the same as everywhere else on this site. Origin stated, treatment stated, and the rare claims that carry premiums, cobalt among them, backed by paper.