The Ruby Guide: origins, quality, prices and expert advice

is corundum coloured red by chromium. The same formula as sapphire, the same hardness, the same absence of cleavage planes, sometimes from the same deposit — only the concentration of chromium separates them.

One consequence of this kinship with sapphire deserves to be known: there is no clear boundary between a highly saturated pink sapphire and a light ruby. There is a chromium threshold, and a tipping point that is debated among laboratories—the GIA places it earlier than the SSEF. Two reports may therefore classify the same gemstone differently, with a considerable price difference.

It shifted around fifteen years ago, and many buyers are still unaware of it.

Burma Burma retains its historic prestige, that of the stones from the Mogok Valley which built the gemstone’s reputation and gave rise to the term “pigeon’s blood”. These stones remain rare on the market, and their sourcing is subject to constraints that complicate traceability.

Mozambique Mozambique has supplied most fine stones since the 2010s, with the Montepuez deposit. Its reds are vivid, often highly legible, and the supply chain is better documented. This is where we source our entire selection.

Other origins exist—Thailand, Madagascar, Tanzania—with distinctive characteristics. But the rule remains the same everywhere: origin explains a character, never a quality. A beautiful stone from Mozambique surpasses an average stone from Burma, whatever the story that accompanies it.

Unlike diamonds, there is no standardised grading scale for rubies. Four criteria matter, and the first outweighs all the others.

A word on commercial names, because they weigh heavily on the price. “Pigeon blood” refers to the most intense reds; some laboratories mention it according to their own criteria, others refuse to do so, and it is not harmonised between them. When it is claimed without supporting documentation, it is worthless.

Finally, inclusions are not assessed as they are in a diamond. Intersecting rutile needles — what the trade calls silk — are an excellent indication of natural origin. Conversely, a perfectly clean stone at a low price should raise questions.

This is the subject that separates a successful purchase from an unpleasant surprise, and it comes down to two cases.

Heating. A traditional, longstanding, stable heat treatment, declared on the certificate, from which the vast majority of rubies on the market benefit. It reveals a colour already present in the stone. An unheated gem is worth more, but a heated stone is by no means devalued — and its care remains identical.

Lead-glass filling. A stone so fractured that it would be unsaleable is impregnated with glass that fills the fissures and makes it visually presentable, often with a very flattering red. Its value bears no relation to that of a heated ruby, and it is unusually fragile : no ultrasound, heat or acidic products. Lemon juice is enough to damage it, and a jeweller retipping a claw with a blowtorch can destroy it.

There is also the question of synthetics: ruby was the first gemstone to be synthesised industrially, from the beginning of the 20th^century , and many antique jewels contain them. For the identifying features to look for and verification methods, our guide to recognising a ruby sets out each case in detail.

Among our six Mozambique rubies in stock in September 2026, the price per carat ranges from €5,800 to €22,500, with a median of around €17,000/ct. Our set creations start at around €8,000.

The most instructive fact from this survey deserves to be highlighted, because it contradicts everything we think we know: the price per carat falls as weight increases. The smallest stone in the lot, a vivid red weighing 1.50 ct, comes in at €22,520/ct; the largest, pinkish, falls to €5,800/ct.

In other words, within this family, colour outweighs weight to the point of reversing the usual pricing logic. The figures for each individual stone, and the comparison with red spinel, can be found in our article on how much a ruby costs.

The two alternatives we most often suggest when the ruby budget does not stretch that far — and they are not judged by the same criteria.

Same mineral · hardness 9

Blue sapphire

Exactly the same durability, for a median price per carat around nine times lower. A blue sapphire engagement ring starts at €2,500, compared with €8,000 for ruby. Set ring, 1.84 ct — 6 360 €.

Different species · hardness 7.5 to 8

Emerald

The same chromium, in green. An emerald engagement ring starts at €1,700 — but it requires a setting that protects its edges, a constraint ruby does not face. Set ring — 10 320 €.

If it is the red that matters rather than the name, there is a third option with six centuries of history: red spinel, almost never treated, whose median price per carat is less than a third of that of ruby. Several “rubies” in royal crowns have in fact proved to be spinels.

This is the simplest part of this guide, and it comes down to three steps.

Once a month, lukewarm water, mild soap, a soft brush — paying particular attention beneath the setting, where a film of cream and dust accumulates. At 9 on the Mohs scale, nothing commonplace can scratch a ruby: what dulls the ring is always the underside of the setting.

Remove the ring for sport, gardening, housework and swimming. The main risk is not scratching, but an impact to a prong, which loosens the setting without anything being visible.

Have the setting checked every two years. A playful prong can tighten within minutes; a lost stone can never be replaced identically. This inspection is offered for life on our creations.