The History of Spinel: From Balas to Now

From the balas rubies of Kuh-i-Lal and the Silk Road to the Crown-Jewels mix-up, the 1783 split from ruby, the 2007 Mahenge discovery and birthstone status in 2016 — spinel's thousand-year story.

Spinel's history stretches from the ancient balas ruby mines of Kuh-i-Lal on the Silk Road, through centuries when Europe's crowns confused it with ruby, to its scientific separation as a distinct mineral in 1783, the electrifying 2007 Mahenge discovery, and its recognition as an official August birthstone in 2016. For a stone so quietly worn by kings, that is a remarkably eventful biography.

No other gem has spent so long being loved under someone else's name. For the better part of a thousand years, the finest red spinels of Central Asia travelled the trade routes as balas rubies, set into imperial regalia, sewn into turbans and recorded in royal inventories as the most precious of red stones. Only chemistry, arriving late in the eighteenth century, finally told the two apart. This is the story of how a mineral crystallising quietly as an octahedron in the marble of Asia's mountains became one of the most fascinating characters in the history of gems.

What do the words "spinel" and "balas ruby" actually mean?

Spinel almost certainly derives from the Latin spinella, a diminutive of spina meaning "little thorn" or "spine" — a nod to the sharp, pointed octahedral crystals the mineral naturally forms. Balas is older still and points to a place. The name is a European corruption of Badakhshan (rendered Balascia in medieval Latin), the mountainous region straddling modern Afghanistan and Tajikistan where the celebrated red mines lay.

So a balas ruby was, quite literally, a "ruby from Badakhshan" — and for centuries the term simply meant a fine red stone from that source, with no suggestion that it was mineralogically different from the rubies of Burma or Ceylon. Medieval lapidaries ranked balas ruby just below true ruby in value, sometimes describing it as softer in colour: a rose-tinged, luminous red rather than the deep pigeon's-blood of corundum. They were, without knowing it, describing exactly the chromium-lit glow of fine red spinel. If you want the full modern picture of why the two stones look so alike, our guide to why spinel is so often mistaken for ruby unpacks the gemmology in detail.

Where does spinel's story begin on the Silk Road?

It begins at Kuh-i-Lal, in the Pamir Mountains of what is now Tajikistan. These mines, worked since at least the ninth century and possibly far earlier, are the oldest documented source of gem spinel on earth, and they produced the great red stones that made the balas ruby famous across Asia and Europe.

Kuh-i-Lal — the name translates roughly as "Mountain of Rubies" — sits above the Panj river on the old Silk Road, and its output flowed both east into the Mughal and Chinese courts and west into Persia, Byzantium and eventually the treasuries of Europe. Marco Polo, passing through the region in the late thirteenth century, recorded that the finest balas stones came from a mountain in "Balashan" and that the local ruler controlled the mines jealously, releasing stones only as royal gifts to preserve their value — one of the earliest written descriptions of deliberate market scarcity. The full account of these workings is worth reading on its own; see our profile of the Tajik Kuh-i-Lal spinel mines. Later sources at Mogok in Burma and Man Sin would add to the supply, but the Pamir stones came first, and they set the standard.

How did spinel end up in the crown jewels by mistake?

Because balas rubies were prized above almost all other red stones, they were set into the most important pieces of regalia in Europe and Asia — and only centuries later did anyone test what they really were. The most famous case is the so-called Black Prince's Ruby, a large, irregular red cabochon set in the front of the British Imperial State Crown, which is not a ruby at all but a spinel of roughly 170 carats.

Its story reads like a chronicle of medieval Europe. It passed from the rulers of Granada into Castilian hands in the fourteenth century, was given to Edward of Woodstock — the Black Prince — and is said to have been worn by Henry V at Agincourt, mounted on his battle helm. Another great spinel, the Timur Ruby, a 361-carat polished pebble engraved with the names of the Mughal emperors who owned it, spent centuries in the treasuries of India and Persia as a supreme "ruby" before likewise being identified as spinel. Both stones sit today among the British Crown Jewels, held in the care of the Royal Collection Trust. We tell these histories in full in our feature on the most famous spinels in history.

The greatest "rubies" in Europe's crowns were spinels all along — the wearers simply had no way to know.

This was not deception so much as the limit of the science available. To the naked eye, and even to the sharpest jeweller's loupe, a fine red spinel and a fine ruby can look identical. Both glow red under light, both come from the same marble deposits, and both were sold side by side by the same merchants. Distinguishing them would require an understanding of crystal structure and optical behaviour that simply did not exist until the Enlightenment. Our comparison of spinel versus ruby shows exactly which properties finally give the game away.

When was spinel finally proven to be its own gem?

The decisive separation came in 1783, when the French mineralogist Jean-Baptiste Louis Romé de l'Isle demonstrated that the stones long sold as balas ruby were chemically and structurally distinct from true ruby. Ruby is corundum, an aluminium oxide; spinel is magnesium aluminium oxide, a different compound with a different crystal habit — and once that was understood, spinel became a mineral in its own right rather than a lesser grade of ruby.

The reasoning that separated them rested on properties any modern gemmologist still uses, and it is worth walking through how the distinction actually works:

1. Crystal habit: spinel grows as octahedra and forms flattened, triangular twinned crystals — the twin law is literally named the spinel law after it — whereas ruby crystallises in the hexagonal system as tabular or barrel-shaped crystals.
2. Optical behaviour: spinel is cubic and therefore singly refractive, so it shows no pleochroism and no doubling of facet edges; ruby is doubly refractive and shows both. This single test separates them cleanly.
3. Chemistry: spinel is MgAl2O4 while ruby is Al2O3 coloured by chromium — the same chromium that lights up fine red spinel, which is why the two colours are so easily confused.
4. Physical constants: spinel has a refractive index around 1.712 to 1.762 and a specific gravity near 3.60, both measurably different from corundum.

With the mineral finally named and defined, spinel spent the nineteenth and much of the twentieth century in a curious limbo — respected by scientists and collectors, yet overshadowed in the wider market by ruby and sapphire. It never quite escaped its old reputation as "the stone that was mistaken for something better," which is one reason it remains, even now, genuinely underrated relative to its quality. To understand the mineral itself in full, our complete guide to natural spinel is the place to start.

There is a quiet irony in that limbo. The very properties that make spinel a superb gem — a hardness of 8 on the Mohs scale, no cleavage, a bright singly-refractive brilliance and, crucially, the fact that it is almost never treated — were the same properties that let it hide inside "ruby" for so long. Where roughly nine in ten blue sapphires on the market today are heated, natural spinel is very rarely subjected to any treatment at all, so the stone in a modern collector's tray is essentially the same, untouched material that a Mughal jeweller would have handled. Few gems offer that kind of unbroken authenticity, and it is a large part of what draws serious buyers to the red spinels that carried the balas name.

What did the 2007 Mahenge discovery change?

In 2007, a spectacular new deposit was discovered at Mahenge in Tanzania, yielding vivid neon-pink and red spinels of a saturation the market had rarely seen. A number of very large, exceptionally clean crystals came out of the ground in the years that followed, and the resulting stones — luminous, almost glowing — did more than any single event to reintroduce spinel to serious collectors and reset its modern reputation.

The Mahenge find mattered for two reasons. First, the sheer quality forced dealers and gem laboratories to take the colour seriously as its own benchmark, not as a ruby substitute. Second, it arrived just as a new generation of connoisseurs was actively hunting for gems outside the traditional "big three," and spinel — untreated, hard, brilliant and historically fascinating — was perfectly placed to answer that appetite. Our Mahenge spinel guide covers the deposit and its finest material, and the broader spinel price guide charts how values have moved since; the GIA spinel buyer's guide is a useful independent reference on quality factors. It is worth remembering that fine red spinel still often trades at roughly a tenth the price of a comparable ruby — a legacy of that long history in ruby's shadow, and one reason many collectors regard today's market as an unusual window.

How did spinel become an August birthstone?

In 2016, spinel was added as an official birthstone for August by the American Gem Trade Association and Jewelers of America, joining peridot and sardonyx. It was the first change to the birthstone list in decades, and it formally recognised what collectors already knew — that spinel had earned a place among the celebrated coloured stones on its own merits.

The choice was fitting. Spinel occurs in a wider range of natural colours than almost any other gem — chromium reds and pinks, cobalt-lit electric blues, iron-tinted greys, violets, lavenders and rare greens — giving August a birthstone of extraordinary versatility. We tell the story of that recognition in spinel joins the August birthstones. Below is a timeline drawing the whole arc together, from the first worked mine to the modern market.

That is the shape of it: a gem that spent a millennium being admired under the wrong name, was rescued by chemistry, and has spent the last two decades quietly reclaiming its reputation. If the history has drawn you in, the natural next step is to see the colours for yourself — explore the full range in our collections, or browse individual stones in the shop. Each one carries a little of this thousand-year story, and, unlike almost every ruby you will encounter, it does so entirely untreated by heat or chemistry.