How a stone’s origin is established

Provenance has become part of the value, and rightly so: the same species changes price depending on where it was born. But “it comes from Kenya” is a technical claim, not a poetic one, and it is worth knowing how it is proven. A laboratory does not read a label: it reconstructs the origin from the stone’s behaviour, crossing two independent readings.

The chemical fingerprint

Rubies, sapphires and emeralds from different areas carry characteristic combinations of trace elements, at different concentrations. With a technique called LA-ICP-MS the laboratory measures these elements below the part per million, building a true chemical fingerprint of the crystal. 1 It is not a colour, not a weight: it is the signature of the foreign atoms that entered the lattice during formation, and that give away the mother rock.

The inner landscape

The second reading is optical. Under the microscope, the inclusions — solid crystals, veils of fluid, growth geometries — draw a landscape that is often typical of a region. For many rubies and sapphires this inner scene weighs more than trace chemistry in determining the origin. 2 The two readings check one another: when they agree, the laboratory commits; when they quarrel, it writes “undetermined”, which is an honest answer.

Every stone carries inside it the memory of the rock that made it. The laboratory simply learns to read it.

Country, not mine

This is where the most common misunderstanding falls. Even the most authoritative origin report gives a country or a geological area, not the single mine. The chemical signature and the inclusions tell the Mozambique Belt from South-East Asia, not one pit from the next. And the determination exists only for a few species. Anyone who promises you the name of the mine on the certificate is promising a precision the instrument does not produce.

No Kimberley for coloured stones

Many take for granted that, for coloured stones, an ethical certification like the Kimberley Process exists. It does not: that system covers rough diamonds only. 3 Around eighty per cent of coloured stones come from small artisanal workings, and the lots are mixed along the chain, which makes provenance hard to trace all the way down. 4 Serious initiatives do exist — declared supply chains such as Moyo and Anza in Kenya, or private programmes with a tracer and a register — but they are projects, not a universal standard. Mistaking them for a guarantee means telling the customer something that is not there.

Our whole idea of provenance is laid out in full in the Rift Valley dossier, where every fact carries its source. Here the rule is enough: we say where the fact ends and the marketing begins.