top of page

Home  /  Coloured gemstones  /  Unheated Rubies

Unheated Rubies

An unheated ruby is a ruby whose laboratory report states no indications of heating, meaning its colour and clarity are as the crystal grew and nothing has been altered by a furnace. Most rubies on the market are heated, so an unheated ruby of fine colour above a carat or two is scarce and carries a premium that grows with size. Byrex Gems offers unheated rubies to the trade from Toronto, filmed unedited in our office, with prices for approved buyers and viewings by appointment.

Where to buy unheated rubies in Toronto

Byrex Gems lists 183 unheated rubies online today. 178 of them come with a report from laboratories including GRS, GIA, SSEF and Gübelin. Origins include Burma (Myanmar), Mozambique, Tanzania and Thailand. Viewings are at our Toronto office, 27 Queen Street East, Suite 407, steps from Queen subway station, by appointment. We have supplied coloured gemstones and natural fancy colour diamonds to jewellers and designers since 1988, and welcome private clients by appointment. Prices are shown to approved trade accounts; private clients can ask us on WhatsApp, where we reply within 12 hours, or by email within 24 hours. Every stone ships insured, worldwide.

Among the unheated rubies listed today: 16.69 ct Oval Cabochon Ruby, Burma Unheated, 13.18 ct Oval Ruby, GIA, Unheated, 12.43 ct Star Oval Ruby, Gübelin + IGI, Burma Unheated, 6.39 ct Oval Ruby, GRS, Burma Unheated, 6.00 ct Oval Ruby, GRS, Madagascar Unheated, 5.62 ct Oval Ruby, GIA, Tanzania Unheated, 5.29 ct Oval Ruby, GRS, Tanzania Unheated, 4.72 ct Oval Ruby, GRS, Burma Unheated, 4.61 ct Round Ruby, GRS, Burma Unheated, 4.57 ct Oval Ruby, GRS, Burma Unheated, 4.45 ct Cushion Ruby, GRS, Burma Unheated, 4.35 ct Pear/Square Ruby Pair (2.21 + 2.14 ct), GRS, Mozambique Unheated and 171 more.

What unheated means and why rubies are heated

Heating a ruby in a furnace can remove blue and brown tints, dissolve silk so the stone looks cleaner and more transparent, and, when a flux is added, heal fractures. The practice became routine in Thailand in the 1970s and 1980s and is now applied to most ruby rough before it is cut. It is accepted in the trade when disclosed.

An unheated ruby has escaped all of that. Its silk is intact, its crystal inclusions are undamaged, and its colour is the colour the deposit produced. In practice that means fine unheated rubies come from the sources whose rough is good enough not to need the furnace: Mogok, the cleaner Montepuez gravels, Winza in Tanzania and parts of Vietnam.

The phrase on the report is the definition. A laboratory does not certify that a stone was never warmed; it states that it found no indications of heating in the inclusions, spectra and surface features it examined. That is the strongest statement available, and it is the one that matters.

How laboratories word heat treatment

GIA, Gübelin and SSEF write "no indications of heating" for an unheated ruby; GRS writes "no indication of thermal treatment". Lotus and AGL state the same finding in their own formats. Where heat is detected the report reads heated or "indications of heating", and if flux has healed fractures the laboratory adds whether the residues in fissures are minor, moderate or significant.

GRS codes the same information: H for heated with no residues, H(a) and H(b) for insignificant and minor residues, H(c) for more, H(d) for significant residues and lead-glass filling, and H(Be) for beryllium diffusion. These codes are useful because they turn a paragraph into a grade a buyer can compare.

"Heat only" and "low heat" are trade terms, not laboratory grades. Heat only means heated without residues or filling. Low heat is a claim about temperature; some gentle heating leaves silk partly intact, but a laboratory that finds evidence of heating reports the stone as heated regardless of how gentle it was. Treat both phrases as a seller's description until a report supports them. Laboratories detect heating by inclusions, spectra and trace-element chemistry, so the finding is not a matter of opinion in the way origin is.

What to check before buying an unheated ruby

Match the report to the stone: weight, measurements and the photograph or inclusion plot should agree, and the report should come from a laboratory you would accept for origin as well as treatment. Check the date, because treatment detection has improved and an old report may deserve an update for an important stone.

Expect to see something inside. Intact silk and small crystals are the signature of an unheated ruby, and a stone that is perfectly clean under the loupe deserves a second look rather than relief. Judge colour viewed from the top under daylight-equivalent and incandescent light; unheated rubies are sometimes a shade less clean in hue than heated ones, and the trade accepts that in exchange for the certainty.

Sizes above two carats are scarce and pairs rarer still, because two unheated rubies must match in hue, tone, fluorescence and origin at once; a close match is often the honest description. At the bench, an unheated ruby with no fissures takes normal handling; one with open fissures noted on the report should be set with care and kept away from the torch.

What drives the value of an unheated ruby

The premium for no indications of heating scales with quality and size. For small commercial stones it is modest, because heated goods of the same look are plentiful. For fine colour above two carats it becomes the single largest factor after colour itself, and at the top of the market an unheated ruby can be worth several times a heated ruby of the same appearance.

Origin compounds it. An unheated Mogok ruby with strong fluorescence is the pinnacle; an unheated Mozambique ruby of pure red is close behind and far more available; unheated Winza and Vietnamese stones are prized by collectors. Clarity and cut matter as they do for any ruby, and a report from a second laboratory adds confidence for important stones.

Heated stones without residues sit one tier below unheated and are the right choice for many commissions. The point of the unheated premium is not that heated rubies are poor; it is that the unheated stone is the rarer object.

Treated, filled and synthetic rubies to recognise

Flux-healed fractures are the most common sign of heating in ruby. The flux, often borax-based, melts into fissures during heating and leaves glassy residues that laboratories record as minor, moderate or significant. Lead-glass filling goes further, flooding fractures and cavities in low-grade rough to make it transparent; the filler shows a tell-tale flash and gas bubbles under magnification and is damaged by heat and acids.

Beryllium diffusion is rarer in ruby than in sapphire but occurs, and it must be disclosed and lowers value; laboratories detect it by trace-element chemistry. Synthetic ruby has been produced since the early 1900s by flame fusion and later by flux growth, and flux-grown synthetics can carry inclusions that resemble natural ones, which is why a laboratory report rather than a loupe is the standard of proof.

The two record rubies of the modern era, the Sunrise Ruby from Mogok and the Estrela de Fura from Mozambique, were both sold with reports stating no indications of heating. The market's highest prices follow the unheated line.

Buying unheated rubies from Byrex Gems

A Toronto house for the jewellery trade since 1988, Byrex Gems counts more than seven thousand jewellers, designers and dealers among its customers. Many of our unheated rubies are accompanied by reports from GRS, SSEF, Gübelin, GIA and other leading laboratories, and each is filmed in our office so that you can judge it before it travels.

Prices are shown to approved trade buyers. For anything else, WhatsApp +1 (437) 450-3786 reaches us within hours, and info@byrex.com is answered the same day, seven days a week. What is listed is a part of what we hold: more unheated rubies are kept in the vault, and what we do not hold ourselves we can source through our offices worldwide. Viewings are by appointment in Toronto, Hong Kong, Bangkok and Dubai.

Unheated Rubies: questions buyers ask

What does no indications of heating mean on a report?

It means the laboratory examined the stone's inclusions, spectra and surface features and found no evidence of heat treatment. It is the standard wording at GIA, Gübelin and SSEF; GRS writes no indication of thermal treatment. It is the strongest statement a laboratory makes about treatment.

How much more is an unheated ruby worth?

There is no fixed ratio. The premium is small for commercial sizes and grows with colour, clarity and size, so that at the top of the market an unheated ruby can be worth several times a heated stone of the same look. Origin and the laboratory behind the report move it further.

Is a low-heat ruby the same as unheated?

No. Low heat is a trade claim about temperature, not a laboratory grade. If a laboratory finds evidence of heating the report says heated, however gentle the process. A ruby sold as low heat should be priced and described as a heated ruby unless its report reads no indications of heating.

Which reports does Byrex supply with unheated rubies?

Every unheated ruby at Byrex carries a report stating no indications of heating from GRS, SSEF, Gübelin, Lotus, GIA or AGL, and important stones often carry two. GRS reports are shown on the stone page. A further report can be arranged on request.

Can an unheated ruby still have fractures or silk?

Yes, and usually does. Intact silk and small crystals are the natural signature of an unheated ruby. Fractures reaching the surface are noted on the report as fissures and matter for setting, but their presence does not change the treatment finding; only filling or heating would.

Does Byrex sell unheated rubies to private clients?

Yes, by appointment at 27 Queen Street East, Suite 407, Toronto. Private clients see the same stones and reports as the trade, and prices are released to approved trade buyers who sign in. Byrex can also source unheated rubies to a specific brief.

Can I compare heated and unheated rubies in Toronto?

Yes. At an appointment the two can be laid side by side under daylight and incandescent light with their reports, which is the quickest way to understand the difference. Each stone is also filmed unedited in our office so you can study it beforehand.

Are unheated rubies always from Burma?

No. Mogok produces many, but Montepuez in Mozambique now supplies most of the unheated rubies in the trade, and Winza in Tanzania and Luc Yen in Vietnam contribute fine examples. The report states origin separately from treatment, so read both lines.

Further reading

Byrex Gems, 27 Queen Street East, Suite 407, Toronto. Coloured gemstones and natural fancy colour diamonds for the trade since 1988, and for private clients by appointment.

Browse by stone

Coloured gemstones

Fancy colour diamonds

bottom of page