The Graff Ruby
The Graff Ruby
An 8.62-carat unheated Mogok cushion of pigeon-blood quality, and a benchmark for the modern ruby market
The Graff Ruby is an 8.62-carat cushion-cut ruby of Burmese origin, widely regarded as one of the finest large rubies to have appeared on the international auction market in the twenty-first century. Originating from the Mogok Stone Tract in Upper Myanmar — the valley historically acknowledged as the world's supreme source of gem-quality corundum — the stone displays the saturated, slightly bluish-red hue known in the trade as pigeon-blood, combined with a degree of transparency and clarity that is exceptional for a ruby of its size. Acquired and set by Graff Diamonds, the London-based house founded by Laurence Graff in 1960, the ruby became a reference point for the premium tier of the unheated Mogok market, where per-carat prices for the very finest stones have consistently exceeded one million United States dollars.
Gemmological Character
Ruby is the red gem variety of the mineral corundum (aluminium oxide, Al₂O₃), with its colour derived principally from chromium substituting for aluminium within the crystal lattice. The chromium content in Mogok rubies is responsible not only for the stone's vivid red body colour but also for a pronounced red fluorescence under both long-wave and short-wave ultraviolet radiation — a phenomenon that, under natural daylight (which contains a significant ultraviolet component), causes the stone to appear to glow from within. This self-luminous quality is considered the defining optical signature of the finest Burmese material and is a primary criterion by which gemmologists and auction specialists distinguish Mogok rubies from those of other origins.
The Graff Ruby's cushion cut — a shape with a rectangular or square outline and rounded corners, combining the brilliance of a modern brilliant with the deeper pavilion proportions inherited from older cutting traditions — is well suited to ruby. Because ruby's refractive index (approximately 1.762–1.770) is lower than that of diamond, cutters prioritise the retention of colour saturation and carat weight over the pursuit of maximum light return, and the cushion outline allows both objectives to be balanced. At 8.62 carats, the stone occupies a size category where truly fine, unheated material of Burmese provenance is extraordinarily scarce.
Clarity in ruby is evaluated differently from diamond. Virtually all natural rubies contain inclusions — needle-like rutile crystals forming the silky silk, fingerprint-pattern healed fractures, and occasionally negative crystals or mineral inclusions of calcite, spinel, or apatite. A ruby described as having exceptional clarity for its size does not imply the absence of all inclusions; rather, it indicates that inclusions are not visible to the unaided eye under normal viewing conditions, do not significantly impair transparency, and do not compromise the structural integrity of the stone. The Graff Ruby's clarity, noted by specialists at the time of its sale, placed it among a very small cohort of large Mogok rubies whose inclusions are sufficiently minor to be considered eye-clean.
Mogok Provenance
The Mogok Stone Tract, situated approximately 200 kilometres north of Mandalay in the Mandalay Region of Myanmar, has been mined for rubies and spinels for at least six centuries, with records of gem extraction under the Burmese kings predating European contact with the region. The geology of Mogok is dominated by a metamorphic complex of marbles, gneisses, and calc-silicate rocks intruded by granitic pegmatites. Ruby forms within the crystalline marbles under conditions of high temperature and pressure, and the relative absence of iron in the marble host — iron suppresses fluorescence in corundum — is the geochemical reason why Mogok rubies fluoresce so intensely compared with rubies from iron-richer sources such as Thailand or Madagascar.
The term pigeon-blood (ko-twe in Burmese) has been used by Mogok traders for generations to describe the most prized colour: a pure, vivid red with a slight bluish undertone that prevents the stone from appearing orange, combined with a tone neither too light nor too dark to suppress saturation. The Gübelin Gem Lab and the Gemmological Institute of America have both published technical criteria for the designation, and leading auction houses — Sotheby's and Christie's in particular — have used the term in catalogue descriptions when supported by laboratory reports. The Graff Ruby received such a designation, which materially contributed to its market valuation.
Crucially, the stone is unheated. Heat treatment — typically carried out at temperatures between 1,600 and 1,900 degrees Celsius, sometimes in the presence of flux or borax — is applied to the great majority of commercial rubies to dissolve silk, improve transparency, and intensify or homogenise colour. Unheated rubies of fine quality are significantly rarer than their heated counterparts, and the premium commanded by a credible no-heat determination from a respected laboratory (the Gübelin Gem Lab, Gemmological Institute of America, or Swiss Gemmological Institute SSEF, among others) can be substantial — often doubling or tripling the per-carat value relative to a comparable heated stone. For a ruby of the Graff stone's size and colour quality, the no-heat status is not merely a technical detail but a primary driver of value.
The Setting and Graff's Involvement
Graff Diamonds has, since the 1970s, pursued a deliberate strategy of acquiring exceptional coloured gemstones and diamonds and presenting them in high-jewellery settings designed to complement rather than overshadow the central stone. Laurence Graff's approach — buying the finest available material regardless of cost, then retaining it until the appropriate setting and client could be found — positioned the house as one of the few private buyers capable of absorbing stones at the very top of the market without the constraints of a public auction timeline.
The Graff Ruby was set in a ring flanked by shield-shaped diamonds. The shield cut — a triangular or kite-shaped outline with straight or slightly curved sides — is a relatively uncommon fancy cut that provides a clean, architectural frame without the visual competition that a more brilliant side stone might introduce. The choice reflects the house's characteristic restraint when presenting a coloured centrepiece of the first order: the diamonds serve to define and elevate the ruby rather than to rival it. The finished ring exemplifies the category of object that auction specialists describe as a jewel rather than merely a piece of jewellery — a distinction that acknowledges the primacy of the gemstone within the composition.
Market Context and Pricing
The market for top-quality unheated Burmese rubies above five carats is among the thinnest and most volatile segments of the entire coloured gemstone trade. Supply is constrained by geology — Mogok produces relatively few large, clean crystals of true gem quality in any given year — and by the political and logistical complexities of operating within Myanmar, which have periodically disrupted the flow of material to international markets. Demand, meanwhile, is driven by a small number of high-net-worth collectors, major jewellery houses, and, increasingly since the 2000s, buyers from mainland China and Southeast Asia for whom fine rubies carry deep cultural significance.
Benchmark sales in the category include the Sunrise Ruby, an 25.59-carat Mogok stone that achieved approximately 30.3 million Swiss francs (roughly 32.4 million US dollars) at Sotheby's Geneva in May 2015, establishing a per-carat world record for ruby at that time. While the Graff Ruby is a different stone of different dimensions, it belongs to the same qualitative tier — unheated, Mogok origin, pigeon-blood colour, exceptional clarity for size — and its valuation reflects the same market logic: extreme scarcity multiplied by superlative quality.
The per-carat threshold of one million US dollars for the finest unheated Mogok rubies, referenced in trade discussions of the Graff stone, is not a fixed price but a market signal indicating that buyers at the apex of the market regard such stones as genuinely irreplaceable. Unlike diamonds, for which the Rapaport price matrix provides a widely used reference grid, ruby pricing at the top end is negotiated privately and is sensitive to the specific combination of colour, clarity, cut, carat weight, origin determination, and treatment status as documented by laboratory report. The Graff Ruby's combination of attributes — particularly its size, its no-heat status, and its pigeon-blood colour designation — places it in a category where comparable stones are measured in single digits globally.
Laboratory Documentation
For any ruby aspiring to the premium tier of the market, laboratory documentation is not optional but essential. The leading laboratories for ruby origin and treatment determination are the Gübelin Gem Lab (Lucerne), the Swiss Gemmological Institute SSEF (Basel), the Gemmological Institute of America (Carlsbad and New York), and Lotus Gemology (Bangkok). Each employs a combination of spectroscopic analysis (ultraviolet-visible, infrared, Raman), microscopic examination, and, where appropriate, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for trace-element fingerprinting to arrive at origin and treatment conclusions.
A laboratory report confirming Burmese origin and the absence of heat treatment for a stone of the Graff Ruby's character would typically include a colour grade using the laboratory's own nomenclature (Gübelin and SSEF both use the term pigeon-blood as a formal colour designation when criteria are met), a clarity assessment, and a statement regarding the presence or absence of indications of heating. The combination of a Burmese origin determination and a no-heat conclusion from one or more of these institutions constitutes the documentary foundation upon which auction estimates and private sale prices are built.
Significance as a Reference Stone
The Graff Ruby occupies a place in the modern ruby market analogous to that of a type specimen in mineralogy: it is a documented, named example against which the quality of other stones may be implicitly measured. Named stones of this character serve several functions within the trade. They establish price benchmarks that inform subsequent negotiations for comparable material. They demonstrate to the broader collecting public that rubies of a certain quality exist and can be authenticated, countering the scepticism that sometimes attaches to a market where synthetic and treated stones are widespread. And they provide auction houses and dealers with a vocabulary of reference — the ability to describe a stone as belonging to the same qualitative tier as a known, documented example carries persuasive weight that abstract grading language alone cannot achieve.
For the specialist, the Graff Ruby is a reminder that the finest Burmese rubies remain among the rarest and most coveted objects in the natural world — stones whose combination of colour, provenance, and geological improbability places them beyond straightforward comparison with any other category of gem material. The valley of Mogok has been mined intensively for centuries, and stones of this calibre are not replenished on any human timescale. Their scarcity is not a market construction but a geological fact, and it is this irreversibility that underpins the sustained and, over the long term, rising trajectory of prices at the very top of the ruby market.