Gemstone and Diamond Laboratories Explained: GIA, GRS, SSEF, Gübelin and More

By the Byrex Gems team, Toronto · Published 25 September 2026

Who issues the report matters. A plain-English guide to GIA, GRS, SSEF, Gübelin, Lotus, AGL, CDC and other laboratories: their history, report types, colour terms and how to verify a report.

A laboratory report is often the most important document that travels with a fine coloured diamond or gemstone. It states what the stone is, records whether it has been treated and, for some gems, gives an opinion on where it was mined. Reports are not interchangeable, however. Each laboratory has its own history, vocabulary and areas of strength. This guide explains the laboratories whose reports appear most often in the fine-stone trade, including those found on Byrex stones, and shows how to check a report online.

The main laboratories at a glance

GIA (Gemological Institute of America)
Headquarters: Carlsbad, California
Founded: 1931
Best known for: The 4Cs, diamond grading, fancy colour diamonds, research
Origin reports?: Yes: diamonds (rough-to-polish matching), coloured diamonds and selected coloured stones

GRS (GemResearch Swisslab)
Headquarters: Meggen, Switzerland
Founded: 1996
Best known for: Ruby, sapphire and emerald origin; GRS-type colour terms
Origin reports?: Yes

SSEF (Swiss Gemmological Institute)
Headquarters: Basel, Switzerland
Founded: 1972
Best known for: Coloured stones, pearls and research; independent foundation
Origin reports?: Yes

Gübelin Gem Lab
Headquarters: Lucerne, Switzerland
Founded: 1923
Best known for: Coloured stones, origin, the Gübelin Gemstone Rating
Origin reports?: Yes

Lotus Gemology
Headquarters: Bangkok, Thailand
Founded: 2013
Best known for: Ruby, sapphire and spinel; named colour types
Origin reports?: Yes, when evidence allows

AGL (American Gemological Laboratories)
Headquarters: New York
Founded: 1977
Best known for: Coloured stones; Prestige reports
Origin reports?: Yes

C. Dunaigre Consulting (CDC)
Headquarters: Switzerland, with a Bangkok laboratory
Founded: 2008
Best known for: On-site and laboratory testing of coloured stones
Origin reports?: Yes

HRD Antwerp
Headquarters: Antwerp, Belgium
Founded: 1973
Best known for: Natural diamond grading
Origin reports?: No (diamond grading focus)

IGI (International Gemological Institute)
Headquarters: Founded in Antwerp; laboratories worldwide
Founded: 1975
Best known for: Diamond and jewellery grading at high volume
Origin reports?: Not a focus

GIA: Gemological Institute of America

GIA was established in 1931 by Robert M. Shipley and is a nonprofit, public-benefit institute. Its global headquarters is the Robert Mouawad Campus in Carlsbad, California, and it runs laboratories and schools in cities including New York, Tokyo, Ramat Gan, Mumbai, Surat, Antwerp, Johannesburg, Gaborone and, since 2024, Dubai. In the 1940s GIA created the 4Cs and the International Diamond Grading System, and it issued its first diamond grading reports in 1953 (GIA).

Coloured diamond reports

GIA offers three reports for natural coloured diamonds (GIA comparison):

Colored Diamond Grading Report: colour grade and origin of colour, clarity grade with a plotted diagram, carat weight, measurements, polish, symmetry and fluorescence. Loose stones of 0.15 carat and above.
Colored Diamond Origin Report: everything in the grading report plus the country of origin, with laser inscription and a photograph included.
Colored Diamond Identification and Origin Report: limited to colour grade, origin of colour (natural or treated), weight and measurements. It has no clarity grade, which makes it suitable for mounted or very small stones.

Note the two meanings of "origin". On the identification report it means the origin of colour, natural or treated. The separate GIA Diamond Origin Report, launched in 2019, confirms the country of origin by matching a polished diamond to rough that GIA examined before cutting (GIA press release).

Coloured stones

GIA issues a Colored Stone Identification Report and an Identification & Origin Report. In a 2019 Gems & Gemology review, GIA listed the gems for which it offers origin opinions: ruby, sapphire, emerald, alexandrite, Paraíba-type tourmaline and red spinel (G&G, Winter 2019). For emeralds, GIA grades clarity enhancement as F1 (minor), F2 (moderate) or F3 (significant) (GIA FAQ).

Verification: GIA reports carry a hologram, a security screen and microprint lines, and the report number can be checked against GIA's database through Report Check (GIA).

GRS: GemResearch Swisslab

GRS was founded in 1996 by Dr Adolf Peretti. Its head office is in Meggen, near Lucerne, and it lists laboratories in Paris, Hong Kong, Bangkok and New York (GRS). It specialises in origin reports for ruby, sapphire and emerald and is closely associated with colour terminology.

GRS-type colour terms

According to GRS, its terms "pigeon's blood" for ruby and "royal blue" for sapphire first appeared in an auction catalogue at Sotheby's London in June 1998. GRS registered them as trademarks in 2015, and in 2017 it split each term into three bands: intense to vivid, vivid, and vivid to deep. Emeralds in the same three green bands receive an "Old Mine/Muzo Green" appendix (GRS colours). Unlike the Swiss laboratories described below, GRS does not require stones to be unheated. It gives the pigeon's blood designation to heated rubies and to rubies of any origin, provided they have the required colour and fluorescence. It refuses the term for beryllium-treated, lead-glass-filled and surface-diffused stones, and for heated stones with its heavier residue grades (GRS pigeon's blood).

Treatment codes

GRS reports use short codes for heated corundum: H (heat, no residues), H(a) to H(d) for increasing amounts of residue in fissures and cavities, with H(d) describing lead-glass-filled "composite" ruby, H(Be) for heat with light-element diffusion, and PHT for heating under pressure. For emeralds it uses a scale from none through insignificant, minor, minor to moderate and moderate to prominent (GRS enhancement disclosure). GRS also offers a Platinum Rarity Gemstone Award, which is covered in our article on premium laboratory distinctions.

Verification: scan the QR code on the report, or enter the report details on the GRS verification page (GRS).

SSEF: Swiss Gemmological Institute

SSEF is a non-profit foundation under Swiss law, set up by the Swiss jewellery trade, and it says it has been testing gemstones since 1972 (SSEF). Its laboratory is in Basel, its specialists also test on site in Bangkok, Hong Kong and the United States, and it publishes widely on coloured stones and pearls. SSEF issues a Diamond Grading Report, a Gemstone Report for single loose natural stones (including coloured diamonds), and a Test Report for mounted pieces, pearls and other items (SSEF reports).

SSEF uses "pigeon blood red" and "royal blue" only for untreated stones. A ruby needs a vivid, strongly saturated red, strong fluorescence under long-wave ultraviolet light, even colour and no disturbing inclusions. A sapphire needs a vivid, saturated blue without greenish, greyish or purple tints (SSEF colour terms). In November 2015 SSEF and Gübelin Gem Lab agreed to harmonise these definitions (IDEX). SSEF reports the amount of oil or resin in an emerald's fissures as minor, moderate or significant. It does not report insignificant amounts (SSEF emerald).

Verification: SSEF reports can be checked, and a digital copy downloaded, at myssef.ch.

Gübelin Gem Lab

Gübelin began in 1923 as a small laboratory for checking the stones used in the Gübelin family's jewellery (Gübelin). The Gem Lab is headquartered in Lucerne, has laboratories in Hong Kong, Bangkok and New York, and runs collection centres in Shanghai and Sri Lanka (Gübelin Gem Lab). Its documents range from the full Gemmological Report to the compact Gem Passport. Most coloured stones submitted for a Gemmological Report now also receive the Gübelin Gemstone Rating, a score expressed in Gübelin Points. Gübelin applies pigeon blood red and royal blue under the definitions harmonised with SSEF. It has announced that from 1 January 2027 it will also use "cornflower blue" for untreated blue sapphires that meet set criteria (Gübelin).

Verification: Gübelin offers online document verification through its services portal.

Lotus Gemology

Lotus Gemology is a Bangkok laboratory founded by Richard W. Hughes, Wimon Manorotkul and E. Billie Hughes. Its own staff pages give 2013 as the founding year (Lotus). It is known for ruby, sapphire and spinel, and for describing colour with named "colour types" such as pigeon's blood, royal, cornflower and padparadscha (Lotus colour types). Hardcover reports are colour-coded: gold for untreated stones, silver for stones with standard enhancements and black for synthetic or heavily treated material (Lotus reports). Reports can be checked through the report lookup on the Lotus website.

AGL: American Gemological Laboratories

AGL was founded in New York in 1977 by C.R. "Cap" Beesley. Christopher P. Smith acquired it in 2009 and refocused it on coloured stones (AGL). Its Prestige Report comes in three levels: identification and enhancement, origin, and full grading, which adds a Total Quality Integration Rating. Clarity enhancement is described as insignificant, minor, moderate and so on, and the filler is identified where possible (AGL Prestige).

CDC: C. Dunaigre Consulting

In the coloured-stone trade, "CDC" on a report generally refers to C. Dunaigre Consulting GmbH. Christian Dunaigre, who previously worked at AIGS in Bangkok and at the Gübelin Gem Lab, set up the company in Switzerland in 2008 for on-site testing. In 2014 he opened C. Dunaigre Gem Lab in Bangkok (C. Dunaigre). It issues gemstone reports covering identification, treatment and origin, jewellery reports, and an optional addendum for exceptional stones (C. Dunaigre reports). Its website offers report verification. Because other companies also use the initials CDC, confirm the issuer's full name on the document.

Diamond-focused laboratories: HRD, IGI and EGL

HRD Antwerp was established in 1973 as the Hoge Raad voor Diamant (Diamond High Council). It was restructured in 2007 into two bodies: HRD Antwerp, which certifies diamonds, and the Antwerp World Diamond Centre. It has laboratories in Antwerp, Mumbai and Dubai (HRD). In June 2025 HRD announced that it would stop issuing quality reports for loose synthetic diamonds from 2026 (AWDC). Reports can be checked on the MyHRD portal.

IGI was founded in Antwerp in 1975. It describes itself as one of the world's largest independent grading laboratories and offers online report verification (IGI).

EGL is a name used by several separately run laboratories. In September 2014 RapNet announced that from 1 October it would stop listing diamonds graded by any EGL laboratory, citing inconsistent grading (National Jeweler). Buyers usually have EGL-graded diamonds regraded.

Other laboratories you may see

GIT (Gem and Jewelry Institute of Thailand): a public organisation under Thailand's Ministry of Commerce, offering gem identification and quality certification (GIT). It is a member of the Laboratory Manual Harmonisation Committee.
AIGS (Asian Institute of Gemological Sciences): founded in Bangkok in 1978 by Henry Ho and Robert Weiser (Wikipedia). Do not confuse it with laboratories trading as "AIG". Unrelated labs in Milan, Israel and Belgium have used that name, and in 2021 a court ordered AIG Belgium to stop using the initials after action by GIA (Rapaport). Always read the full name on an "AIG" report.
AGTA Gemological Testing Center: the American Gem Trade Association's New York laboratory announced its closure in July 2009 (Southern Jewelry News). Its reports are now historical documents. An important stone is usually resubmitted to a current laboratory.
Argyle certificates: Rio Tinto's Argyle mine in Western Australia ran from 1983 until November 2020 and, according to Rio Tinto, produced about 90% of the world's pink diamonds (Rio Tinto). JCK reports that Argyle pinks over 0.08 carat were laser-inscribed and came with a certificate of authenticity from the mine (JCK). Argyle used its own colour codes, so many Argyle stones also carry a GIA report that grades them on GIA's scale.
Smaller or older reports (for example GRI, IGL, GIS): several unrelated laboratories have used these initials, and some such reports are decades old. Ask the seller for the laboratory's full name and how to verify the report. For a significant stone, consider a current report from a major laboratory.

Harmonisation between laboratories

The Laboratory Manual Harmonisation Committee (LMHC), formed in 2001, publishes shared wording for reports. Its current members are CGL (Japan), CISGEM (Italy), DSEF (Germany), GIA, GIT, Gübelin Gem Lab and SSEF. Its information sheets cover heated and glass-filled corundum, padparadscha, emerald fissure filling, Paraíba tourmaline, cobalt spinel, tanzanite and colour stability testing (LMHC). There is no LMHC sheet for pigeon's blood or royal blue, so those terms still depend on each laboratory's own criteria. Read them with the issuing lab in mind.

How to verify a report

Confirm the laboratory's full name and look for its security features, such as a hologram, microprint or QR code.
Use the laboratory's own verification service: GIA Report Check, GRS report verification, myssef.ch, Gübelin document verification, the Lotus report lookup, MyHRD or IGI's verify page.
Check that the weight, measurements, shape and colour online match the stone in front of you. For diamonds, also check any laser inscription under magnification.
Note the report date. Opinions describe the stone at the time of testing, and emerald fillers in particular can change.

If you have a question about a stone and its laboratory report, email info@byrex.com or send a WhatsApp message to +1 (437) 450-3786.