A GRS certificate — formally a gemological report issued by GemResearch Swisslab (GRS), headquartered in Lucerne, Switzerland — is one of the most widely recognised documents in the international coloured-gemstone trade. Founded by gemmologist Adolf Peretti in 1996, GRS has built its reputation principally on the identification and origin determination of rubies, sapphires, and emeralds, and on a suite of proprietary colour-quality designations that have become commercially significant benchmarks in their own right. The laboratory operates additional offices in Bangkok, Hong Kong, New York, and Tokyo, positioning it at the heart of the major gem-trading centres where its reports are most actively requested.

Format and Contents

GRS reports are issued in a distinctive booklet format — a departure from the single-sheet style used by some competing laboratories — and typically contain the following elements:

• Identification data: species, variety, and, where determinable, geographic origin.
• Physical measurements: weight in carats and millimetre dimensions.
• Colour description: using both standard gemmological terminology and, where applicable, GRS's proprietary colour-quality designations.
• Clarity and transparency assessment.
• Treatment status: a conclusion as to whether the stone has been subjected to heat treatment, fracture filling, beryllium diffusion, or other enhancement processes.
• Photomicrographs: high-magnification images of diagnostic inclusions, which serve both as scientific documentation and as a means of identifying the specific stone if it is ever separated from its report.
• A security hologram and unique report number for authentication purposes.

The inclusion of photomicrographs is a particularly valued feature among serious collectors, as it provides a visual fingerprint of the stone and supports the origin conclusion by illustrating the inclusion assemblage characteristic of a given deposit.

Proprietary Colour-Quality Designations

GRS is perhaps best known in the trade for its proprietary colour-quality terms, which are applied when a stone meets internally defined spectrophotometric and visual criteria. The most commercially significant of these are:

• Pigeon's blood — applied to rubies of a specific saturated red hue with a slight blue undertone, historically associated with Mogok, Burma (Myanmar), though GRS applies the designation on the basis of colour parameters rather than origin alone.
• Royal blue — applied to sapphires exhibiting a vivid, medium-dark blue considered the benchmark of the finest Kashmir, Burmese, and Sri Lankan material.
• Vivid green — applied to emeralds of exceptional saturation.
• Cornflower blue — a secondary sapphire designation associated with a lighter, more violet-tinged blue, often linked to Sri Lankan stones.
• Lotus — applied to pink sapphires of a particular warm, saturated hue.

These designations carry no standardised international definition outside GRS's own methodology, and other major laboratories — including Gübelin Gem Lab and SSEF (Swiss Gemmological Institute) — use different terminologies or apply similar terms according to differing criteria. The lack of cross-laboratory standardisation is a recognised issue within the trade and among gemmological bodies. Nevertheless, within the markets where GRS reports are most influential, particularly across East and Southeast Asia, the presence of a pigeon's blood or royal blue designation on a GRS certificate has been documented to command a meaningful premium at auction and in private sale.

Origin Determination

Geographic origin determination is among the most technically demanding tasks in applied gemmology, and it is a core competency that GRS has invested in heavily since the laboratory's founding. Origin conclusions are reached through a combination of standard refractometry, spectroscopy (including UV-Vis-NIR and FTIR), trace-element analysis by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and the examination of inclusion assemblages. GRS has published research on origin determination methodology in peer-reviewed and trade publications, and Adolf Peretti has contributed extensively to the scientific literature on ruby and sapphire provenance.

Origin conclusions on GRS reports are expressed with varying degrees of confidence — typically as a definitive statement of origin or, where the evidence is ambiguous, as a statement that the stone's characteristics are consistent with a named locality. The distinction is commercially important: a definitive Mogok or Kashmir origin attribution on a fine ruby or sapphire can substantially affect realised price at auction.

Market Recognition and Commercial Impact

GRS certificates are among the most requested documents for high-value coloured stones sold at the major international auction houses, including Christie's, Sotheby's, and Bonhams, as well as in the private dealer and wholesale markets of Bangkok, Hong Kong, and Taipei. The laboratory's influence is particularly pronounced in the Asian gem trade, where GRS's colour-quality designations have become embedded in the vocabulary of buyers and sellers.

The commercial premium associated with a favourable GRS colour designation — most notably pigeon's blood for ruby — has been widely reported in auction results and trade commentary. Stones bearing this designation from GRS (or from the other two members of the so-called "Big Three" Swiss laboratories, Gübelin and SSEF) consistently achieve higher per-carat prices than comparable stones without such a designation, reflecting the market's confidence in the laboratories' methodologies and the scarcity of stones that genuinely meet the criteria.

It should be noted that a GRS certificate, like any gemological report, is an opinion document issued at a specific point in time. It does not constitute a guarantee of value, and the conclusions expressed — particularly regarding origin and treatment status — reflect the state of gemmological knowledge and analytical technology at the time of examination. Buyers and dealers are advised to treat laboratory reports as one input among several when assessing a stone, alongside their own examination and, for significant purchases, consultation with an independent gemmologist.

Relationship to Other Major Laboratories

GRS operates alongside Gübelin Gem Lab (Lucerne) and SSEF (Basel) as one of the three Swiss laboratories most widely recognised for coloured-stone origin and quality reports. While all three are respected internationally, they differ in their methodologies, the precise criteria applied to colour designations, and the markets in which they have the strongest commercial presence. GRS's particular strength in the Asian market and its booklet format with photomicrographs distinguish it from its Swiss peers. For buyers and sellers active across multiple markets, reports from more than one laboratory are sometimes obtained for the same stone, particularly when a stone is being prepared for a major auction.

Further Reading

• Gems & Gemology — GIA's peer-reviewed journal, available at gia.edu
• GIA Laboratory services overview — gia.edu