Gübelin report

A Gübelin report is the grading credential issued by Gübelin Gem Lab in Lucerne, Switzerland. Together with SSEF, Gübelin is one of two top-tier global authorities for colored gemstone origin and treatment determination; the two labs are roughly equal in trade weight, with Gübelin sometimes preferred for very-top-tier lots at European auction and SSEF sometimes preferred for Asian auction lots. Both reports are accepted at full credential weight by Christie's, Sotheby's, Bonhams, and Phillips for top-tier colored-stone lots.

Gübelin issues full grading reports including stone species identification, measurements, color description, treatment disclosure, and country-of-origin determination. The origin call uses LA-ICP-MS trace-element chemistry plus inclusion-fingerprint analysis plus FTIR spectroscopy plus Raman spectroscopy plus UV-Vis-NIR absorption — Gübelin runs more analytical techniques in parallel than most labs, which is part of why the origin calls are trusted at the top of the market.

Gübelin's distinguishing feature is its supplementary color and quality designations. The lab uses "pigeon blood" on ruby with explicit internal reference standards, "royal blue" and "cornflower blue" on sapphire with their respective references, and "gota de aceite" on Colombian emerald when the optical phenomenon is present at significant intensity. These designations carry independent pricing weight at auction beyond the basic origin call — a stone with "gota de aceite" called by Gübelin trades materially higher than a stone with the same visible color and same origin call but no gota de aceite designation.

The full Gübelin report on a top lot is sometimes accompanied by a "Gemmological Information" supplementary document that explains the stone's notable features in detail. The supplementary documentation is reserved for exceptional stones and is part of what auction catalogues cite when describing the lot's provenance and quality.

Gübelin also issues a separate "Gübelin Provenance Proof" service — a forensic origin determination using nanoparticle markers introduced at the mine that allows the lab to confirm a stone's specific mine source rather than just country of origin. The service is offered by a few specific mining operators (notably Belmont in Brazil and Gemfields in Zambia and Mozambique) as part of supply-chain transparency programs; the resulting reports identify the stone's mine of origin with technical certainty rather than statistical inference.

Gübelin Gem Lab is operationally separate from Gübelin Jewellery (the historic jewelry house that founded the lab) but shares the brand heritage. The lab has been independent of the jewelry business for decades and accepts submissions from any source.

For investment-grade colored stones at the top of the market, Gübelin paper is interchangeable with SSEF paper as the trade-standard credential.