Gem Identification

Systematic gem identification follows a fixed sequence to avoid confirmation bias. Start with non-destructive observations (colour, transparency, lustre), then move to refractive index, then specific gravity, then the spectroscope if the RI falls in an ambiguous range. Only after these quantitative steps should qualitative tests (Chelsea filter, fluorescence) be applied to confirm or refute a working hypothesis. This sequence matches the FGA Diploma practical examination protocol, and it matters because qualitative tests are sensitive to treatment, coating, and imitation, whereas RI and SG are intrinsic physical constants of the material itself.

The gem identifier on this page applies this logic directly. Enter the RI reading from your refractometer, the SG value from hydrostatic weighing, the crystal system if known from polariscope behaviour, and the optic character (singly refractive, uniaxial, or biaxial). Each parameter constrains the search independently, and the tool returns every family in the 96-entry mineral database that satisfies all the criteria you supply simultaneously. You do not need to fill in every field; a single RI reading already eliminates the majority of species, and adding SG typically reduces the candidate list to three or fewer families. The underlying database includes all 93 natural mineral families as well as 13 synthetic, 11 simulant, and 4 composite entries, so lookalike materials appear in the same results set as genuine natural species.

Results are displayed with origin badges that immediately flag whether a matching entry is a natural mineral, a lab-grown synthetic with the same chemical composition, a simulant made from a different material, or a composite assembled stone. This distinction is critical at the identification stage: a stone with an RI of 1.762 and SG of 3.99 could be natural ruby, flux-grown synthetic ruby, or a garnet-topped doublet, which are three very different commercial situations that require different follow-up tests. Seeing all three in a single ranked results table prevents the common error of stopping investigation once a plausible natural species is found.

After the identifier narrows the field, the results table provides direct links to the relevant entries in the spectroscope band-matcher and UV fluorescence lookup, so the next logical test is always one click away. This end-to-end workflow, from first observation to a confirmed identification supported by multiple independent properties, is the foundation of professional gemmological practice and the standard taught at the Gemmological Association of Great Britain.