GRS report designations are the proprietary terminology and structured coding system employed by GemResearch Swisslab (GRS), the Swiss gemmological laboratory founded by Dr. Adolf Peretti in 1996, to communicate three interrelated categories of information on a single certificate: colour quality, geographic origin, and treatment status. Unlike the relatively standardised language shared among laboratories such as Gübelin and SSEF, GRS developed its own lexicon of colour-quality appellations — most notably pigeon blood for ruby, royal blue for sapphire, and vivid green for emerald — that have acquired independent commercial weight in the international coloured-stone trade. The system is widely recognised by dealers, auction houses, and collectors, and a GRS designation appended to a report can materially influence the price a stone commands at sale.

Background and Laboratory Context

GemResearch Swisslab is headquartered in Lucerne, Switzerland, with satellite offices in Bangkok, Hong Kong, and New York, positioning it at the centre of the major coloured-stone trading hubs. The laboratory specialises primarily in ruby, sapphire, spinel, and emerald — the species for which precise origin and treatment determination carries the greatest commercial consequence. GRS reports are structured documents that typically include a stone description, spectroscopic and chemical data, an origin conclusion, and a treatment conclusion. When a stone meets the laboratory's internally defined reference standards for an exceptional colour grade, GRS issues a supplementary colour-quality appendix — sometimes called a type designation — that carries the relevant colour appellation. This appendix is considered a separate, additional statement beyond the standard report, and its issuance is not automatic.

Colour-Quality Appellations

The most commercially significant GRS designations are the colour-quality terms applied to the three principal coloured stones:

• Pigeon blood (ruby): The term pigeon blood has historical roots in the Burmese and broader Asian trade, where it described the finest red rubies from Mogok — a saturated, slightly fluorescent red with a faint blue undertone. GRS formalised this as a measurable standard, defining it against a reference set of stones and specifying that the colour must be assessed under standardised lighting conditions. A GRS pigeon blood designation is among the most sought-after appellations in the coloured-stone market and is associated with a significant price premium, particularly for Burmese rubies, though the designation is not restricted to Burmese origin.
• Royal blue (sapphire): Applied to sapphires displaying a vivid, saturated blue of medium to medium-dark tone, the royal blue designation is most commonly associated with sapphires of Burmese (Mogok or Mong Hsu) or Kashmiri origin, though again the appellation is a colour descriptor rather than an origin statement. It is distinguished from the slightly lighter or more violet-toned blues that the laboratory would describe without a colour-quality appendix.
• Vivid green (emerald): Applied to emeralds of intense, pure green saturation, the vivid green designation is less frequently encountered than the ruby and sapphire equivalents, partly because emerald colour assessment is complicated by the near-universal presence of clarity treatments and by the diversity of source localities — Colombian, Zambian, Brazilian, and others — each with distinct colour character.

GRS has also issued colour-quality designations for other species, including vivid red for spinel and, in some reports, descriptive colour terms for alexandrite and other collector stones, though these carry less standardised market recognition than the three principal appellations above.

Treatment Coding and Disclosure Language

Parallel to its colour-quality system, GRS employs a structured vocabulary for communicating treatment status. For heat treatment — the most commercially consequential treatment for ruby and sapphire — GRS uses a graduated scale of disclosure terms:

• No indications of heating (unheated): The highest-value conclusion, indicating that the laboratory found no gemmological evidence of thermal treatment. GRS may issue this as a standalone conclusion or, for qualifying stones, as part of a GRS-type 'unheated' designation, which combines the no-heat conclusion with a colour-quality appellation (e.g., GRS-type 'pigeon blood' unheated). This combined designation represents the apex of the GRS coding hierarchy for ruby and sapphire.
• Indications of heating — insignificant: Applied to stones showing minor evidence of heat exposure, typically residual stress fractures or subtle alteration of inclusions, where the degree of treatment is judged to be minimal. This category occupies a commercially intermediate position.
• Indications of heating — minor: Indicates more evident but still limited evidence of heat treatment, without the presence of glass or flux fillings.
• Indications of heating — significant (with indications of glass/flux residues): The most heavily treated category, applied to stones where fracture-filling or flux healing is detected, substantially reducing commercial value relative to unheated or lightly heated equivalents.

For emerald, GRS uses analogous language for clarity enhancement by oils, resins, or polymers, typically describing the degree of filling as insignificant, minor, moderate, or significant — a framework broadly consistent with the AGTA and Gübelin disclosure scales, though the precise thresholds are laboratory-specific.

Commercial Significance and Market Influence

The GRS designation system has achieved substantial influence in the coloured-stone auction market. Major auction houses — including Christie's, Sotheby's, and Bonhams — routinely cite GRS colour-quality appellations in lot descriptions for important rubies and sapphires, and the presence of a pigeon blood or royal blue designation is frequently noted as a factor in pre-sale estimates. The GRS-type 'pigeon blood' unheated combination, in particular, has become a benchmark for the finest Burmese rubies offered at international auction.

It should be noted, however, that colour-quality appellations are laboratory-specific and are not universally standardised across the industry. Gübelin Gem Lab and SSEF (Swiss Gemmological Institute) use their own terminology — SSEF, for example, employs pigeon blood colour and royal blue colour as descriptors, while Gübelin uses comparable language — and the precise criteria defining each appellation differ between laboratories. This means that a stone receiving a pigeon blood designation from one laboratory may not receive the equivalent from another, a nuance that sophisticated buyers and their advisors are expected to understand. The Gemmological Association of Great Britain (Gem-A) and the GIA do not issue colour-quality appellations of this type on their standard reports.

Interpretation and Due Diligence

For buyers and dealers working with GRS-designated stones, several interpretive points merit attention. First, the colour-quality appendix is a separate document from the main report; both should be present and consistent for the designation to be considered valid. Second, the designation applies to the stone as examined at the time of testing — subsequent re-cutting, re-polishing, or re-treatment would necessitate re-submission. Third, the unheated conclusion reflects the limits of current gemmological detection; it is a statement that no indications of heating were found, not an absolute guarantee of natural thermal history. This distinction is standard across all major laboratories and is not a limitation unique to GRS.

The GRS coding system, taken as a whole, represents one of the most detailed and commercially embedded designation frameworks in the coloured-stone laboratory sector. Its appellations have moved beyond purely descriptive function to become, in effect, a grading shorthand that the international trade has incorporated into pricing structures, auction cataloguing, and collector discourse.

Further Reading

• Gems & Gemology — GIA Publications
• AGTA Gemstone Treatment Disclosure Policy
• Lotus Gemology — Laboratory and Treatment Articles