GRS Report
GRS Report
Colour grading, origin determination, and proprietary colour designations from GemResearch Swisslab
A GRS report is a gemological laboratory certificate issued by GemResearch Swisslab (GRS), a Lucerne-based laboratory founded in 1996 by Dr Adolf Peretti. GRS reports provide species and variety identification, geographic origin determination, and disclosure of any detectable treatments. The laboratory is particularly well regarded in the international coloured-stone trade for its proprietary colour-quality designations — most notably pigeon blood for ruby and royal blue for sapphire — which, when awarded, carry measurable influence on market valuation.
Scope of a GRS Report
A standard GRS report addresses four principal areas. First, it confirms the identity of the stone: species, variety, and, where relevant, whether the material is natural or synthetic. Second, it provides a geographic origin opinion, drawing on the laboratory's reference collection of stones from documented localities including Mogok, Mong Hsu, Mozambique, Kashmir, Sri Lanka, and Colombia, among others. Third, it discloses the presence or absence of heat treatment and, where applicable, identifies more invasive treatments such as fracture filling, beryllium diffusion, or lead-glass impregnation. Fourth, for qualifying stones, it may append a colour-quality designation.
Proprietary Colour Designations
GRS introduced formalised colour-quality terminology that has since become embedded in auction-house catalogue language and dealer correspondence worldwide. The two most commercially significant designations are:
- Pigeon blood — awarded to rubies that meet the laboratory's defined hue, saturation, and tone criteria, historically associated with the finest Mogok production. The designation appears as a supplementary appendix to the main report rather than as part of the standard grading text.
- Royal blue — awarded to sapphires exhibiting a specific range of deep, velvety blue, most commonly associated with Kashmir and certain Burmese material, though the designation is applied on the basis of colour alone rather than origin.
Additional colour designations exist within the GRS system — including vivid green for emerald and padparadscha for the distinctive pinkish-orange sapphire — each governed by the laboratory's internal reference standards. Because these designations are proprietary and defined by GRS's own criteria, they are not directly interchangeable with the colour-quality language used by Gübelin Gem Lab or SSEF, the two other Swiss laboratories with which GRS is most frequently compared.
Market Standing and Trade Acceptance
GRS reports are accepted by major international auction houses including Christie's, Sotheby's, and Bonhams, and are routinely requested by dealers trading in Burmese ruby, Kashmir sapphire, and Colombian emerald — stone categories where origin and colour quality carry the greatest premium. The pigeon blood appendix in particular has become a recognised shorthand in auction catalogues, where its presence on a Mogok ruby is frequently cited alongside carat weight and origin as a primary value driver. Stones carrying GRS pigeon blood or royal blue designations consistently command price premiums relative to otherwise comparable stones graded without such an appendix.
Relationship to Other Swiss Laboratories
GRS operates alongside Gübelin Gem Lab (Lucerne) and SSEF — the Swiss Gemmological Institute (Basel) — as part of a trio of Swiss laboratories whose reports are considered the global benchmark for high-value coloured stones. Each laboratory maintains its own methodologies and reference collections, and minor divergences in origin opinion between laboratories are not uncommon, particularly for stones from localities with overlapping spectroscopic signatures. Sophisticated buyers and dealers frequently seek reports from more than one Swiss laboratory when transacting in stones of significant value.