Understanding a laboratory report

A laboratory report, often called a certificate, records what an independent laboratory established about a stone. It is not a sales contract, not a valuation and not a guarantee, but an expert description at the time of the examination.

Structure of a typical report

• Report number and date: used for matching and verification
• Identification: species and variety, for example "corundum, variety ruby"
• Description: weight in carats, shape, cut, dimensions in millimetres, colour
• Treatment: changes detected or not detected
• Origin: an expert opinion, if requested
• Comments: additional information, for example on colour terms or limitations
• Photograph: shows the stone examined

For diamonds, grading of colour, clarity and cut as well as fluorescence are added.

Differences between laboratories

Leading laboratories such as GIA, SSEF, Gübelin or GRS sometimes use their own terms. Colour names such as "Pigeon Blood" or "Royal Blue" are not uniformly defined. The Laboratory Manual Harmonisation Committee (LMHC) works to standardise wording, but differences remain. Reports from different laboratories are therefore not always directly comparable.

What a report does not say

A report states no price and no value. It describes the stone on the day of examination; later damage, treatments or substitution are not included. That is why the link between stone and report is so important.

The age of a report

Methods keep developing. A report issued many years ago may not yet have been able to detect certain treatments. For valuable stones a current report is therefore advisable.

In brief

A laboratory report describes the stone at the time of examination: identification, description, treatment and possibly origin. It is not a valuation. Read every field in its exact wording and check that the report belongs to the stone.

At NOBILITH

Every stone has at least one report from a recognised independent laboratory. The dossier presents the information as the laboratory worded it, and the report number can be verified with the laboratory. The articles in this section explain the individual fields.

Sources

• LMHC: Information Sheets
• GIA, SSEF, Gübelin: explanatory notes on their reports