American Gemological Laboratories (AGL) is a New York-based gemological testing laboratory founded in 1977, specialising exclusively in coloured gemstones. Among the longest-established independent laboratories of its kind in the United States, AGL has built its reputation on rigorous identification of species and variety, determination of geographic origin, and detection of treatments — the three pillars of modern coloured-stone certification. Its reports are accepted by major auction houses, dealers, and collectors internationally, and the laboratory is regarded as a primary authority within the American coloured-stone market.

History and Leadership

AGL was established in 1977 at a moment when the coloured-gemstone trade was beginning to demand independent, scientifically grounded documentation to support the growing importance of origin and treatment disclosure. The laboratory is currently led by Christopher P. Smith, a gemmologist whose career has been closely identified with AGL and who has contributed substantially to the technical literature on ruby, sapphire, and emerald. Under Smith's direction, AGL has maintained a focus on coloured stones rather than expanding into diamond grading, a deliberate specialisation that has allowed the laboratory to develop particular depth in the analysis of corundum, beryl, chrysoberyl, and other coloured species.

Scope of Services and Report Types

AGL issues several categories of report, the most comprehensive of which is the AGL Prestige report. This document provides a full gemmological profile of a stone, including:

• Species and variety identification
• Geographic origin determination
• Assessment of clarity and colour enhancement
• Spectroscopic and chemical data where relevant
• A colour description grounded in objective measurement

The laboratory also issues shorter identification reports and, for stones of particular significance, extended technical commentary. AGL's origin determinations cover the principal producing localities for ruby (Mogok, Mong Hsu, Mozambique, Thailand), sapphire (Kashmir, Burma, Ceylon, Madagascar, Montana), emerald (Colombia, Zambia, Brazil, Zimbabwe), and a wide range of other coloured species. Origin attribution at AGL, as at other leading laboratories, is based on a combination of gemological observation, spectroscopy, trace-element chemistry, and comparative reference data accumulated over decades.

Treatment Detection and Disclosure

Treatment detection is a central function of the AGL report. The laboratory assesses and discloses the presence or absence of the principal enhancements relevant to each species: heat treatment in corundum; fracture filling and flux healing in ruby; oiling, resin impregnation, and dyeing in emerald; beryllium diffusion in sapphire and other corundum; and lead-glass filling in heavily included rubies. AGL employs a graded disclosure system that characterises not merely the presence of a treatment but, where determinable, its degree — a distinction of considerable commercial significance in the emerald trade, where the extent of clarity enhancement directly affects value.

The laboratory does not employ trade-name colour designations such as pigeon blood or royal blue on its standard reports, preferring instead to describe colour in objective gemmological terms. This approach reflects a commitment to scientific neutrality and avoids the marketing connotations that have attached to such terms in the broader trade.

ColorScan and Colour Measurement

One of AGL's notable technical contributions is the development of its proprietary ColorScan system, a spectrophotometric approach to colour description that translates a stone's measured reflectance and transmission characteristics into a standardised colour profile. ColorScan was designed to provide a reproducible, instrument-based record of colour that could serve as an objective reference independent of the variable conditions of visual grading — lighting environment, observer adaptation, and stone orientation. While colour grading in coloured gemstones remains inherently more complex than in diamonds, and no single system has achieved universal adoption across the trade, ColorScan represented an early and serious attempt to bring quantitative rigour to a field that had long relied on subjective description.

Research and Publications

AGL has contributed to gemmological knowledge through its association with GemDialogue, a colour-communication system developed to provide a standardised visual reference for coloured-stone colour description, and through contributions to industry publications including Coloured Stone magazine, which for many years served as the principal trade journal of the American coloured-gemstone industry. Christopher P. Smith has authored technical articles on origin determination, treatment detection, and the gemmology of specific species, adding to the peer-reviewed and trade literature that underpins modern laboratory practice.

Position in the Laboratory Landscape

AGL operates within a competitive international landscape that includes Gübelin Gem Lab (Lucerne), SSEF Swiss Gemmological Institute (Basel), Gemmological Institute of America (GIA, Carlsbad and New York), and Lotus Gemology (Bangkok), among others. Each laboratory has its own methodological emphases, reference databases, and market constituencies. AGL's particular strength lies in its long institutional experience with coloured stones in the North American market context, its detailed treatment-disclosure methodology, and its established relationships with the American dealer and auction community. For stones destined for the American market, an AGL Prestige report is frequently requested alongside or in preference to European laboratory reports, reflecting the laboratory's recognised standing among American buyers and their advisers.

It should be noted that, as with all gemological laboratories, an AGL report documents the stone's condition and characteristics at the time of examination; it does not constitute a valuation or an appraisal, and the conclusions on origin and treatment represent expert gemmological opinion based on available evidence rather than absolute certainty — a qualification that applies equally to every reputable laboratory in the field.

Further Reading

• Gems & Gemology — GIA's peer-reviewed journal, gia.edu
• AGTA Gemstone Information Resources, agta.org