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Unheated Gemstones

An unheated gemstone is a stone whose colour and clarity are as it came out of the ground, confirmed by a laboratory report stating that no indications of heating were found. For ruby and sapphire, where heating is routine, the finding separates a small minority of stones from the rest of the market; for spinel and garnet, which are seldom heated, the word untreated is used instead. Byrex Gems offers unheated stones to the jewellery trade from Toronto, filmed unedited, with prices for approved buyers and viewings by appointment.

Among the unheated gemstones listed today: 11.08 ct Oval Yellow Sapphire, GIA, Ceylon Unheated, 3.08 ct Cushion Teal Sapphire, GIA, Madagascar Unheated, 21.80 ct Square Cushion Blue Sapphire, GIA, Ceylon Unheated, 18.96 ct Cushion Blue Sapphire, GIA, Unheated, 18.09 ct Oval Yellow Sapphire, GRS, Ceylon Unheated, 17.37 ct Oval Vivid Yellow Sapphire, GIA, Unheated and 315 more.

What unheated means and why it matters

Heating is the oldest and most widespread gemstone treatment. Rough is heated, sometimes to well over a thousand degrees, to dissolve silk, improve transparency, deepen or lighten colour, or remove unwanted tints. For ruby and sapphire it has been standard practice for decades, and the great majority of corundum sold today has been heated. The treatment is permanent and accepted by the trade, but it must be disclosed.

An unheated stone is one in which a laboratory has found no evidence of heating. The evidence lies in the inclusions, which heat alters in characteristic ways, and in the spectra and trace-element chemistry. Laboratories detect heating by these inclusions, spectra and chemistry, and state their finding in their own words.

The species where the finding carries the most weight are ruby and sapphire, because heating is the norm and unheated fine stones are scarce. Tourmaline, particularly copper-bearing Paraíba type stones and rubellite, is next, since heating is common there too. Spinel, garnet and a few other species are seldom heated, and for them a report that no treatment was found is the expectation rather than the distinction.

How laboratories word an unheated finding

Each laboratory has a standard phrase, and the phrase belongs to that laboratory. GIA states "no indications of heating" on its coloured stone reports when none are found, and describes evidence of heating when it is. SSEF and Gübelin use wording to the same effect, "no indications of heating", and both describe treatments found in their own terms. GRS states "no indication of thermal treatment" for unheated stones and uses its own codes and descriptions for heated ones, including the distinction between heating with and without residues in fissures.

The finding is a conclusion from evidence, not a guarantee of history. Where the evidence is ambiguous, a laboratory may say so, and low-temperature heating of some stones leaves few traces, which is why the trade relies on laboratories with large reference collections and advanced instruments. A report that is silent on heating, or that notes heating is common for the type and cannot be determined, as is the case for aquamarine and tanzanite, is not an unheated report.

For species that are rarely heated, the usual wording is that no indications of treatment, or of heating or other treatment, were found. Spinel and garnet reports normally carry this line as a matter of course.

What to check when buying an unheated stone

Read the report before the stone. Confirm that the laboratory is one the trade relies on for treatment work and that the wording is a positive finding of no indications of heating in that laboratory's phrase, not a comment that heating cannot be determined.

Then judge the stone on its own merits, viewed from the top under daylight-equivalent light and under incandescent light. Unheated stones are not automatically finer; many are heated precisely because their colour or clarity needed help, and an unheated stone with weak colour is simply a weak stone with a premium attached. The purpose of the finding is to let you pay for a fine colour that nature produced, not to excuse a poor one.

Silk and other fine inclusions are often present in unheated corundum and are part of what makes the finding possible; a light silk that softens the light is accepted and can be beautiful, while heavy silk that greys the stone is a fault. Pairs of unheated stones are scarce and Byrex describes two stones as a pair only when the parcel paper or report says so, otherwise as a close match.

What drives the premium for unheated stones

The premium for an unheated finding depends on how rare it is within the species and how fine the stone is. In ruby and sapphire, where most stones are heated, an unheated report on a stone of fine colour adds a substantial premium, and the premium grows with the colour and the size: a large unheated Burmese ruby or Kashmir or Ceylon sapphire of top colour is among the most valuable objects in the coloured stone trade. On a stone of commercial colour, the same finding adds much less, because the market for that colour is set by heated goods.

Origin and the unheated finding reinforce each other. The market associates certain origins with unheated stones of exceptional colour, Burma and Mogok for ruby, Kashmir and Sri Lanka for sapphire, and a report that states both is the standard for the top of the market.

In tourmaline, an unheated report adds a premium for Paraíba type stones and rubellite and is of little consequence for colours that are not usually heated. In spinel, garnet, tsavorite and the other species sold as untreated, the absence of treatment is the baseline and carries no premium of its own; what those stones offer is freedom from the question altogether, which many buyers and private clients now value.

Unheated stones in the market and at auction

Heating of corundum has been practised for centuries and became industrial in Thailand and Sri Lanka in the second half of the twentieth century, when furnaces capable of controlled high temperatures transformed large quantities of pale or silky rough into saleable blue and red stones. The laboratories responded with the methods that now separate heated from unheated material, and the two-tier market followed: heated stones as the commercial standard, unheated stones as the collector's and connoisseur's category.

At auction, the finest rubies and sapphires are almost always offered with reports stating no indications of heating, and catalogues lead with that finding alongside the origin opinion. The record prices for ruby and sapphire belong to unheated stones, and the gap between an unheated and a heated stone of similar appearance widens as the size and quality rise.

Supply is thin at every level because fine unheated rough has always been scarce. Byrex holds unheated ruby, sapphire, spinel and tourmaline with reports and sources specific unheated stones to a brief through its offices and partners.

Buying unheated gemstones 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 gemstones 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 stones 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 Gemstones: questions buyers ask

What does unheated mean on a gemstone report?

That the laboratory found no evidence of heating in the stone's inclusions, spectra and chemistry. GIA, SSEF and Gübelin state "no indications of heating"; GRS states "no indication of thermal treatment". Each phrase belongs to its laboratory, and Byrex quotes the one on the report.

Why are unheated sapphires and rubies more expensive?

Because most corundum is heated and fine unheated stones are scarce. The premium rises with colour and size: it is substantial on a fine stone and modest on a commercial one. An unheated report lets a buyer pay for colour that nature produced.

Why is spinel called untreated rather than unheated?

Because heating is not standard practice for spinel, garnet and a few other species, so a report normally states that no indications of treatment were found as a matter of course. The distinction that unheated carries for ruby and sapphire does not apply in the same way.

Is an unheated stone always better than a heated one?

No. Many stones are heated because their colour or clarity needed help, and an unheated stone with weak colour is a weak stone with a premium attached. Judge the colour and clarity first, then let the finding and the report adjust the value.

Which laboratories does Byrex rely on for unheated findings?

GIA, GRS, SSEF, Gübelin, Lotus and AGL, depending on the stone. Each states the finding in its own wording, and for high-value stones two reports from different laboratories are common. The report number and wording appear on every stone page.

Can a laboratory be wrong about heating?

The finding is a conclusion from evidence, and low-temperature heating of some stones leaves few traces, so laboratories with large reference collections and advanced instruments are relied on. Where evidence is ambiguous the report says so. Treat an unheated claim without a report as only a claim.

Does Byrex source unheated stones for a specific commission?

Yes. Byrex holds unheated ruby, sapphire, spinel and tourmaline with reports and sources specific unheated stones through its offices and partners. State the species, colour, size, origin and the laboratories you accept, and Byrex will present candidates filmed unedited with their reports.

Can I see unheated stones and their reports in Toronto?

Yes, by appointment at 27 Queen Street East, Suite 407, Toronto. Each stone is shown under daylight-equivalent and incandescent light with its original report, so the wording on heating and origin can be read beside the stone.

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.

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