October 01, 2026

Spinel: The Gem That Fooled the Crown Jewels — and Why Collectors Want It Now

By Sasha Tarasova

Filed under Gemstone GuidesJewelry Eras & HistoryBuying Guides

Short answer: Spinel is a gemstone species of its own, a magnesium aluminium oxide, that was mistaken for ruby for centuries. Two of the most famous "rubies" in the British Crown Jewels, the Black Prince's Ruby and the Timur Ruby, are in fact red spinels. Spinel is hard (8 on the Mohs scale), usually sold untreated, and fine red, pink and cobalt-blue stones are now genuinely valuable.

For most of the twentieth century spinel was the gem trade's consolation prize: the stone you were told about after the ruby turned out to be something else. That reputation has flipped. Collectors, gemmologists and a lot of dealers now argue that a fine spinel is one of the best-value coloured stones you can buy. We agree, with some caveats about what "fine" means and what spinel is not.

What is spinel?

Spinel is a mineral species with the chemical formula MgAl2O4, magnesium aluminium oxide, and it crystallises in the cubic system, typically as sharp octahedra. That makes it chemically and structurally different from ruby and sapphire, which are both corundum, aluminium oxide.

The confusion is geological as much as historical. Spinel and corundum form in similar marble-hosted deposits, often side by side in the same gravels, and the same trace element that makes ruby red, chromium, makes spinel red too. A miner washing gravel in Myanmar in 1500 had no way to separate the two red pebbles in his pan, and for trade purposes nobody much tried.

The old name: balas ruby

Medieval and Renaissance inventories often call red spinel a "balas ruby", a name usually traced to Badakhshan, the mountainous region on today's border between Tajikistan and Afghanistan where the historic spinel mines were. The term acknowledged that the stone was a slightly different kind of red, but it was still filed under ruby. Separating spinel as a distinct species is generally credited to late eighteenth-century mineralogy, with the French mineralogist Jean-Baptiste Romé de l'Isle often named, and the distinction became settled science over the following decades as chemical analysis and crystallography matured. Treat the exact dates with some caution: sources differ on who deserves the credit and when the trade actually caught up.

Are the Crown Jewels "rubies" really spinels?

Yes. The two best-known cases are documented by the Royal Collection itself and by generations of gemmological literature.

The Black Prince's Ruby

The large red stone set at the front of the Imperial State Crown, above the Cullinan II diamond, is a spinel of roughly 170 carats. Tradition connects it to Edward of Woodstock, the Black Prince, in the fourteenth century, and to Henry V at Agincourt. Those stories are old and much repeated; the provenance before the seventeenth century is better described as tradition than as record. What is not in doubt is the identification: it is a polished, irregular spinel, drilled at the top in the old manner so it could be hung, with the hole later plugged by a small ruby.

The Timur Ruby

The Timur Ruby is an unfaceted red spinel of more than 350 carats set in a necklace in the British Royal Collection. It is engraved in Persian with the names of several former owners, among them several Mughal emperors, which makes it one of the few great gems that carries part of its own ownership record on its surface. It entered the royal collection in the mid-nineteenth century. The name associating it with the conqueror Timur is itself disputed by historians; the inscriptions do not include him.

Similar re-identifications have run through other European and Russian treasuries. The large red stone at the top of the Great Imperial Crown of Russia is also generally described as a spinel. The pattern is consistent: the biggest "rubies" of pre-modern Europe were very often spinels, because big clean spinels occur more readily than big clean rubies.

Red spinel vs ruby: how do you tell them apart?

By eye, often you cannot, and you should not try to settle it without instruments. In a lab or with gemmological tools the two separate cleanly, because spinel is singly refractive and ruby is doubly refractive.

• Refraction. Ruby, like all corundum, splits light into two rays (double refraction). Spinel, being cubic, does not. A refractometer or polariscope separates them in seconds.
• Pleochroism. Ruby shows two colours when viewed along different directions through a dichroscope, typically purplish red and orangey red. Spinel shows one colour from every direction.
• Colour character. Fine red spinel tends to be a slightly "cleaner", sometimes more orange or more pink red, without ruby's purplish secondary tone. This is a tendency, not a test.
• Inclusions. Spinel commonly shows tiny octahedral crystals, sometimes in rows, the so-called "octahedral negative crystals" (cavities shaped like the host crystal). Ruby tends to show silk (fine rutile needles) and growth zoning at angles typical of corundum.
• Hardness. Ruby is 9 on the Mohs scale, spinel 8. Facet edges on a worn antique spinel may show slightly more abrasion than a ruby of the same age. Nobody should scratch-test a stone to find out.

If you own a ring described as ruby and want the answer, a standard gemmological report from a laboratory such as GIA identifies the species and reports detectable treatments. Our guide to judging whether a gemstone is fine covers what to look at once you know what the stone is.

What colours does spinel come in?

Spinel occurs in more colours than most people expect, and each has its own following and price logic.

Red

The classic. Top red spinel from Mogok in Myanmar is the benchmark: a saturated, bright red that glows because spinel, like ruby, fluoresces red under ultraviolet, and daylight contains ultraviolet. Brownish or dark reds are far more common and far cheaper.

Pink and "hot pink"

Vivid pink to magenta spinels became widely known after an important find near Mahenge in Tanzania, commonly dated to the late 2000s, which produced some large, very bright pink stones. Pastel pinks are more common and priced accordingly.

"Jedi" spinel

"Jedi" is a trade nickname, not a scientific grade, for spinels with an intense, almost neon red-to-pink colour and no visible grey or brown dulling, usually from Mogok or Mahenge. Because the term has no formal definition, treat it as a description the seller is offering, not as something a laboratory has certified.

Cobalt blue

Most blue spinels owe their colour to iron and read as greyish or steely blue. A small minority are coloured by cobalt and show a saturated, electric blue that iron cannot produce. Cobalt spinel is rare, known mainly from Sri Lanka and Vietnam, and fine stones are expensive, usually small. A laboratory can confirm cobalt as the colouring agent, and for a stone sold on that basis it should.

Everything else

Lavender, purple, violet, grey, orange ("flame" spinel) and near-black also occur. Grey and lavender spinels have a quieter following among designers because they give a very clean, steely look at a reasonable price.

Where does spinel come from?

The main sources, historic and current:

• Myanmar (Mogok and Namya). The reference source for red and pink. Mogok material carries a premium when a laboratory report states the origin.
• Tajikistan (the historic Badakhshan mines, Kuh-i-Lal). The source of many historic balas rubies. Output today is intermittent.
• Tanzania (Mahenge and elsewhere). Pinks and reds, including some large clean crystals.
• Sri Lanka. Wide colour range from gem gravels, including some cobalt blues.
• Vietnam (Luc Yen). Reds, pinks, purples and cobalt blues.

Origin reports are opinions, reached from inclusions and trace-element chemistry. Different laboratories occasionally disagree, and older or unusual stones can defeat origin determination altogether. Pay for origin only when the report states it.

Is spinel treated?

Usually not, which is one of its strongest selling points. Most spinel on the market is sold as it came from the ground, cut and polished. Compare that with ruby and sapphire, where heating is routine, and emerald, where oiling is routine.

"Usually" is not "always". Heat treatment of spinel has been reported and is sometimes detectable, and occasional stones have filled fractures. As with any coloured stone of real value, a laboratory report is how you confirm it. Our guide to which gemstone treatments are accepted and which are value-killing puts spinel in context against the other big colours.

Synthetic spinel: the antique jewelry trap

Here is the part that matters most to anyone buying older jewelry. Synthetic spinel has been manufactured by the flame-fusion (Verneuil) process since the early twentieth century, and it was used heavily, not to imitate natural spinel, but to imitate other gems.

• Light blue synthetic spinel was widely sold as a stand-in for aquamarine and blue zircon.
• Darker blue synthetic spinel imitated sapphire.
• Green, pink and colourless synthetic spinels appear as imitations of peridot, tourmaline, and even diamond in inexpensive pieces.

These show up constantly in mid-twentieth-century jewelry: class rings, birthstone rings, costume and lower-carat gold pieces, and sometimes in otherwise respectable Art Deco and Retro-era settings. They are not "fake" in the sense of fraud; much was sold openly as synthetic. They are a problem only when someone later describes the piece as set with aquamarine or sapphire.

Gemmologists separate synthetic from natural spinel by refractive index (flame-fusion material usually reads slightly higher), by the strained, patchy extinction it shows under a polariscope (called anomalous double refraction), and by gas bubbles or unnatural growth features under magnification. None of these are reliable home tests. A dealer who sells you a mid-century "aquamarine" ring should be able to tell you how they know. If you are buying a blue stone in a period sapphire ring, the same question applies.

Is spinel durable enough for an everyday ring?

Yes. Spinel is 8 on the Mohs scale, harder than quartz-family gems such as amethyst and citrine and harder than emerald, and it has no cleavage, meaning no plane along which it tends to split cleanly. It is tough enough for an engagement ring worn daily, with the usual caveats about hard knocks on any faceted stone.

It will still pick up abrasion on facet edges over decades if worn next to diamonds or knocked against stone countertops. Our Mohs hardness guide for jewelry you actually wear explains why hardness and toughness are different properties, and why an 8 is a comfortable place to be.

Is spinel valuable?

Fine spinel is valuable and has risen in price over the last two decades. Ordinary spinel remains affordable. The gap between the two is wide, and most of the price sits in colour.

What drives the price

1. Colour first. Saturation and brightness in red, hot pink and cobalt blue command the highest prices. Brownish, greyish and dark tones fall away steeply.
2. Size. Clean spinel over roughly five carats is uncommon in the top colours, and prices per carat rise with size.
3. Origin, when documented. Mogok red and pink, and cobalt from Vietnam or Sri Lanka, carry premiums when a report states them.
4. Clarity. Spinel is expected to be eye-clean in top grades. Visible inclusions cut the price hard.
5. Cut. Many spinels are cut for weight retention and look dark or windowed. A well-cut stone that stays bright across the whole face is worth a clear premium.

Why prices rose

Several things happened at once. Gemmologists and dealers spent years advocating for spinel as an honest, untreated alternative to heated ruby. New deposits produced enough fine material for the market to see it, but never enough to flood it. The crown-jewel story made spinel easy to explain. And buyers who might have chosen a heated ruby noticed they could have an untreated stone of stronger colour for the same money. We would add a caution: rising prices in coloured stones are a market fact, not a guarantee. Our view of jewelry as an investment applies here without modification.

Spinel vs its neighbours

As a rough ordering, not a price list: fine unheated ruby of good size sits above fine spinel; fine red spinel generally sits above average heated ruby; and good pink spinel competes with pink sapphire on price. Neon Paraíba tourmaline and cobalt spinel are both collector colours with small supply, and both reward buyers who insist on laboratory paperwork. At the affordable end, spinel is a natural next step for anyone who already likes the underrated antique gemstones such as garnet and amethyst but wants more hardness.

Spinel in antique and vintage jewelry

Natural spinel turns up in period jewelry more often than descriptions admit. Georgian and Victorian pieces catalogued as "ruby" are sometimes set with spinel, or with a mixture of spinel, ruby and garnet chosen for colour rather than species. Many older pieces have never been tested at all.

This cuts both ways. A ring sold as ruby may be spinel and therefore overpriced. A ring sold as "red stone" may hold a good natural spinel and be underpriced. A small three-stone piece such as our vintage diamond and ruby pinky ring is the kind of piece where species matters to price but not to how it wears; on a single large red centre stone, it matters a great deal. A dealer should tell you whether a red stone was identified or merely assumed. That is part of what we mean by what a dealer should disclose.

A buying checklist for spinel

1. Get the species confirmed. For any spinel sold at a meaningful price, ask for a laboratory report or a written gemmological identification.
2. Ask about treatment in writing. "No indications of heating" on a report is the phrase you want.
3. Look at the stone in daylight and indoors. Red spinel that looks brilliant under shop lights can turn brownish in shade.
4. Check the face for windowing and dark zones. Many spinels are cut deep to save weight.
5. On vintage blue and light-blue stones, ask whether synthetic spinel has been ruled out.
6. Pay for origin only when the report states it. "Burmese" in a listing is not an origin determination.

Questions people actually ask

Is spinel a real gemstone or a fake ruby?

Spinel is a real, natural gemstone species in its own right, with its own chemistry and crystal structure. It was confused with ruby historically because both are red and occur together in the same deposits. Natural spinel is not an imitation. Synthetic spinel, made in a laboratory since the early twentieth century, has often been used to imitate other gems, which is a separate issue.

Is spinel more valuable than ruby?

Usually not at the top of the market. Fine unheated ruby of good size generally costs more than fine red spinel. But a fine spinel commonly costs more than an average heated ruby, and many collectors prefer an untreated spinel with strong colour to a heavily treated ruby at a similar price. Compare quality to quality, not species to species.

Is spinel a good choice for an engagement ring?

Yes. Spinel is 8 on the Mohs scale, has no cleavage, and is usually untreated, so it wears well and needs no special handling beyond sensible care. Red, pink, lavender and grey spinels are all used as centre stones. As with any coloured stone, a protective setting helps if you work with your hands.

What is Jedi spinel?

Jedi spinel is a trade nickname for spinel with an intense, glowing red to hot-pink colour and no grey or brown undertone, typically from Mogok in Myanmar or Mahenge in Tanzania. It is not a laboratory grade, so the label depends on the seller's judgment. Ask to see the stone in daylight and ask what report supports the description.

How can I tell if my spinel is natural or synthetic?

Not reliably at home. Gemmologists separate them using refractive index, the strained pattern synthetic spinel shows in a polariscope, and inclusions under magnification such as gas bubbles. Natural spinel often contains tiny octahedral crystals. For any stone of real value, a laboratory report is the only sensible answer.

Why are the Crown Jewel rubies called rubies if they are spinels?

Because the names were given centuries before gemmology could separate the two species, and famous stones keep their names. The Black Prince's Ruby and the Timur Ruby have been known by those names for generations, and the names are historical rather than scientific. Nobody at the Royal Collection claims they are corundum.

If you want a spinel as the centre of a ring, whether a Mogok red, a hot pink or a steely grey, we can find the stone and design the setting around it through our bespoke service, or search the market for a period piece through private sourcing. Browse our current antique and vintage rings or more writing on coloured gemstones in the Journal.