Melee Diamond Quality Control: How Sampling Works

Melee diamonds are small diamonds used in groups, often in watches and jewellery. Checking thousands of tiny stones creates a different practical problem from grading one large diamond. A laboratory needs a clear plan for what to inspect and how to report the result.

Why use a representative sample?

SSEF’s 2007 article explains quality control using a representative sample from a lot. This approach depends on a suitably defined, reasonably homogeneous batch and clear quality criteria. It does not mean that every stone has received an individual grade.

Colour, clarity and cut still matter. Tiny size makes some observations harder, so the way results and uncertainty are communicated is important. A sample report should be read in the context of the sampling plan.

What does AQL mean?

An acceptable quality level, or AQL, is used with a sampling plan to decide whether a lot meets an agreed acceptance rule. The buyer’s chosen rule affects the outcome. It should not be read as a guarantee that an accepted lot contains no defects.

Quality and identity are separate questions

Assessing a sample for colour and clarity is not automatically a full examination of every stone’s natural or laboratory-grown origin. Ask which checks were carried out, how many stones were examined and what the report covers. The article is a historical explanation, not a specification of today’s sampling standards.

Sources and further reading

SSEF Swiss Gemmological Institute, Facette, issue 14, January 2007, pp. 4-5, “Quality Control for Large Quantities of Small Diamonds”. Read the original SSEF PDF.

This independent educational article explains historical SSEF research in original, simple English. It is not an SSEF publication. No source photographs or illustrations are reproduced.