Ruby Gemstone
Hold a fine ruby under a warm lamp and the red appears to come from somewhere inside the stone.
That impression is accurate.
Ruby is one of the few gemstones that fluoresces. It absorbs light and gives part of it back as red, so the colour reaching your eye is partly reflected off the surface and partly emitted from within. The effect is faint in an ordinary stone and unmistakable in a fine one.
People noticed this long before anyone could explain it. Antiquity had no word for fluorescence and reached instead for the obvious comparison, grouping red stones under the Latin carbunculus, little coal. The Greeks called them anthrax, burning coal, for the way they took on the colour of embers held up to the sun. Medieval jewellers went further and priced a ruby by how much it seemed to glow: not at all, or only when water was poured over it, or best of all entirely on its own, like a live coal. Six centuries before anyone could account for the effect, the trade was already paying a premium for it.
A stone that appears to hold fire collects stories about fire, and about blood, and about everything those two stand in for. Rubies were carrying that weight in betrothal rings for centuries before the diamond solitaire existed, which is part of why a ruby can feel inherited even when it is new.
The fluorescence is also why rubies photograph so badly, and why nobody in the trade will buy one from an image. You have to watch it move on a hand.
The colour comes from chromium. Ruby is corundum, colourless in its pure form and the same mineral as sapphire, and chromium enters the crystal as it grows and turns it red. The more the stone takes in, the deeper the red runs.
Chromium is also difficult. It distorts the structure it sits in, seeding fractures and inclusions while the crystal is still forming. The consequence is awkward for anyone who wants both things at once: the most intensely coloured rubies tend to be the most flawed. Above two carats fine rubies thin out quickly, and a good five-carat ruby is a considerably rarer object than a good five-carat sapphire.
The first two drops
Burmese dealers had a name for the best of it.
In the Mogok valley, where rubies have been surfacing for close to a thousand years, the finest red was called pigeon's blood: the first two drops, and only the first two.
Local legend gives the stone an older beginning still. An eagle, the oldest in creation, sights a piece of fresh meat on a hillside and stoops for it. Its claws will not go in. After many attempts it understands what it is holding. Not flesh, but a stone made from the fire and blood of the earth.
The phrase has travelled since. Laboratories now award pigeon's blood on the evidence of the colour alone, wherever the stone was found, in part because Mozambique has spent more than a decade producing reds that stand beside Mogok's finest. Origin still moves prices at auction, though it has stopped being a reliable promise about beauty, and it now carries a second question worth asking: where did this stone come from, and who benefited on its way here.
Most rubies have been heated. The practice is ordinary, openly declared, and it works, drawing out colour the stone was holding back.
A small number arrive from the ground with that colour already present. Nothing was added and nothing corrected, and at the top of the market such a stone commands several times the price of a heated equivalent. A report from Gübelin, the SSEF or the GIA is what makes the claim mean anything, which is why serious stones travel with paperwork.
Geneva, May 2015: the "Sunrise Ruby"
The Sunrise Ruby ran to 25.59 carats. Burmese, unheated, graded pigeon's blood, set by Cartier between two shield-shaped white diamonds.
Two collectors fought over it by telephone. It sold for US$30.42 million at Sotheby's Geneva, more than twelve million above the highest estimate, and the Sunrise Ruby holds the record for any ruby to this day. The accompanying Gübelin report observed that rubies of this quality are generally found only in small crystals, which is a very composed way of noting that nobody had expected to see one this size.
It remains the most valuable coloured gemstone ever sold at auction that was not a diamond, a distinction the auctioneer took care to draw on the night.
Made to be worn
Ruby sits at 9 on the Mohs scale, one step below diamond and above anything an ordinary day will involve. You can wear it to work, in the rain, for thirty years.
Very few stones this rare are also this practical, which is part of why rubies make such sound engagement rings. Hard enough for daily wear, warmer than a colourless solitaire, and unlikely to resemble anyone else's.
Finding yours
Colour first, always, and trust your own eye over any vocabulary handed to you. Look for saturation that holds its depth while staying clear of darkness, and notice whether the red pulls toward orange, pink or purple, since a pure red is worth more and looks it. Then ask about heat, then origin, then the certificate standing behind both.
The setting comes last. Its only job is to get out of the way of the stone.
At Canturi we reach for rubies when a piece needs warmth as well as presence. Set in yellow gold, framed in pavé, or left entirely alone. If you would like to see one properly, and properly means in person and under warm light, book an appointment with us.
Ruby at a glance
Ruby at a glance
| Mineral species | Corundum, the same mineral as sapphire |
| Colouring element | Chromium |
| Mohs hardness | 9, second only to diamond at 10 |
| Birthstone month | July |
| Historic source | Mogok valley, Myanmar, mined for close to a thousand years |
| Major modern source | Montepuez, Mozambique, in commercial production since around 2009 |
| Finest colour grade | Pigeon's blood, a saturated pure red with a faint blue undertone |
| Auction record | The Sunrise Ruby, 25.59 carats, US$30.42 million, Sotheby's Geneva, May 2015 |
| Record price per carat | Approximately US$1.18 million, the highest for any ruby |
| Standard treatment | Heat, to improve colour and clarity, disclosed and accepted across the trade |
> Why are fine rubies so rare?
Chromium is the reason. Chromium turns colourless corundum red, and the more a ruby contains the deeper its colour, but chromium also strains the crystal structure as the stone forms, seeding fractures and inclusions. The most intensely coloured rubies are therefore the most likely to be flawed, which is why large clean rubies of fine colour are far scarcer than large sapphires. Above two carats, fine rubies become rare very quickly.
> What is a pigeon's blood ruby?
Pigeon's blood is the gem trade's name for the finest ruby colour: a saturated pure red with a faint blue undertone and strong fluorescence. The term began among dealers in the Mogok valley in Myanmar and was long reserved for stones of proven Burmese origin. Major gemmological laboratories including Gübelin and GRS now award it against defined colour criteria, wherever the stone was mined.
> What is the difference between a ruby and a sapphire?
Ruby and sapphire are the same mineral, corundum, which is colourless in its pure form. Chromium makes it red and the stone is called ruby. Iron and titanium make it blue and the stone is called sapphire. Every other colour of corundum is classed as sapphire, so ruby is the only variety with a name of its own.
Ruby and sapphire are the same mineral, corundum, which is colourless in its pure form. Chromium makes it red and the stone is called ruby. Iron and titanium make it blue and the stone is called sapphire. Every other colour of corundum is classed as sapphire, so ruby is the only variety with a name of its own.
> Are unheated rubies worth more than heated rubies?
Considerably more. Heat treatment improves colour and clarity, it is standard practice across the trade and it is openly disclosed, so the great majority of rubies on the market have been heated. A ruby of fine colour that has never been heated is uncommon and commands several times the price of a comparable heated stone at the top of the market. Certification from a laboratory such as Gübelin, the SSEF or the GIA is what makes the distinction verifiable.
Considerably more. Heat treatment improves colour and clarity, it is standard practice across the trade and it is openly disclosed, so the great majority of rubies on the market have been heated. A ruby of fine colour that has never been heated is uncommon and commands several times the price of a comparable heated stone at the top of the market. Certification from a laboratory such as Gübelin, the SSEF or the GIA is what makes the distinction verifiable.
> Where do the finest rubies come from?
Historically the Mogok valley in Myanmar set the benchmark, and Mogok stones still command a premium at auction. Since around 2009 the Montepuez deposit in Mozambique has produced rubies that rival Mogok's finest, and major laboratories now grade the pigeon's blood colour without regard to origin. Origin still affects price, though it is no longer a reliable guide to quality on its own, and provenance and ethical sourcing have become part of the same question.
Historically the Mogok valley in Myanmar set the benchmark, and Mogok stones still command a premium at auction. Since around 2009 the Montepuez deposit in Mozambique has produced rubies that rival Mogok's finest, and major laboratories now grade the pigeon's blood colour without regard to origin. Origin still affects price, though it is no longer a reliable guide to quality on its own, and provenance and ethical sourcing have become part of the same question.
> How can I tell whether a ruby is real?
Laboratory certification is the only reliable answer, and any ruby of significant value should be accompanied by a report from Gübelin, the SSEF or the GIA. Visual clues are suggestive rather than conclusive: natural rubies almost always contain some inclusions, they fluoresce under warm light in a way that makes the colour appear lit from within, and a stone with completely uniform colour and perfect clarity at a low price is more likely to be synthetic or glass filled. Synthetic rubies are chemically identical to natural ones and cannot be identified by hardness testing.
Laboratory certification is the only reliable answer, and any ruby of significant value should be accompanied by a report from Gübelin, the SSEF or the GIA. Visual clues are suggestive rather than conclusive: natural rubies almost always contain some inclusions, they fluoresce under warm light in a way that makes the colour appear lit from within, and a stone with completely uniform colour and perfect clarity at a low price is more likely to be synthetic or glass filled. Synthetic rubies are chemically identical to natural ones and cannot be identified by hardness testing.
> Is a ruby a good choice for an engagement ring?
Yes. Ruby sits at 9 on the Mohs scale, second only to diamond, which makes it well suited to daily wear over decades. The considerations are treatment and clarity rather than hardness: a heavily included or fracture-filled ruby wants gentler handling than a clean stone. Ruby offers a warmer alternative to a colourless diamond solitaire and is far less likely to resemble anybody else's ring.
Yes. Ruby sits at 9 on the Mohs scale, second only to diamond, which makes it well suited to daily wear over decades. The considerations are treatment and clarity rather than hardness: a heavily included or fracture-filled ruby wants gentler handling than a clean stone. Ruby offers a warmer alternative to a colourless diamond solitaire and is far less likely to resemble anybody else's ring.
> What is the most expensive ruby ever sold?
The Sunrise Ruby, a 25.59 carat unheated Burmese ruby graded pigeon's blood, sold for US$30.42 million at Sotheby's in Geneva in May 2015. That is approximately US$1.18 million per carat and it remains the auction record for any ruby. It is also the most valuable coloured gemstone ever sold at auction that is not a diamond. Coloured diamonds reach considerably higher figures per carat.
The Sunrise Ruby, a 25.59 carat unheated Burmese ruby graded pigeon's blood, sold for US$30.42 million at Sotheby's in Geneva in May 2015. That is approximately US$1.18 million per carat and it remains the auction record for any ruby. It is also the most valuable coloured gemstone ever sold at auction that is not a diamond. Coloured diamonds reach considerably higher figures per carat.
> How should I care for a ruby?
Store a ruby apart from your other jewellery, because ruby will scratch almost anything it touches and diamond will scratch ruby. Avoid ultrasonic cleaning if the stone has surface-reaching inclusions or has been fracture filled, since vibration can worsen both. Warm water and a soft brush are sufficient for routine cleaning. Canturi clients are invited to return pieces to us annually so we can check the setting and restore the surface.
Store a ruby apart from your other jewellery, because ruby will scratch almost anything it touches and diamond will scratch ruby. Avoid ultrasonic cleaning if the stone has surface-reaching inclusions or has been fracture filled, since vibration can worsen both. Warm water and a soft brush are sufficient for routine cleaning. Canturi clients are invited to return pieces to us annually so we can check the setting and restore the surface.
> Which month has ruby as its birthstone?
Ruby is the traditional and modern birthstone for July.
Ruby is the traditional and modern birthstone for July.
