Some sources have become names to conjure with: Mogok for ruby, Kashmir for sapphire, Colombia for emerald, Ceylon for both. Stones from these sources can command multiples of the price of equivalent stones from elsewhere, so the question "where is it from?" is worth a great deal of money — and it is one of the hardest questions a laboratory is asked.
What origin is not
Origin is not a property of the stone in the way refractive index is. A Burmese ruby and a Mozambican ruby are the same mineral with the same RI and SG. Nothing about the crystal says "Burma". What differs is the geological environment in which each grew, and that environment leaves indirect traces: which minerals were around to be included, which trace elements were in the growth fluid, what the growth conditions did to the crystal's zoning and structure.
Origin determination is therefore inference from those traces, compared against reference collections of stones of known origin. It is an expert opinion, and every serious laboratory labels it as such.
What the evidence consists of
Inclusion suite. Certain inclusions are characteristic of certain deposits. Short, dense rutile silk and calcite crystals in Burmese ruby; long needles and specific mineral guests in Sri Lankan sapphire; the fine "milky" zoning of Kashmir sapphire; three-phase inclusions in Colombian emerald. None is unique to its source, but the combination narrows the possibilities.
Trace-element chemistry. Instruments such as LA-ICP-MS or EDXRF measure the concentrations of iron, titanium, chromium, gallium, vanadium and other elements at parts-per-million levels. Different deposits have different chemical fingerprints — Burmese ruby is typically low in iron, Thai and many African rubies higher; Colombian emerald has a distinctive vanadium-to-chromium relationship. Plotted against reference data, a stone's chemistry falls in the region of one source or another.
Spectroscopy. UV-Vis and FTIR absorption features can reflect the growth environment and separate, for instance, basaltic from metamorphic sapphire.
Growth features. Twinning, zoning patterns and crystal habit.
The laboratory weighs all of these and reaches a conclusion expressed with a stated confidence.
Why it is difficult
Deposits overlap. New sources appear with characteristics resembling old ones — Mozambican ruby can resemble Burmese; Madagascan sapphire can resemble Sri Lankan or Kashmir. Reference collections are never complete. Very clean stones offer few inclusions to examine. Heated stones have had their inclusions altered. And the premium for a prestigious origin creates pressure on laboratories, whose credibility depends on resisting it.
Reputable laboratories issue origin opinions only with the chemical instruments to support them, and they disagree with one another more often on origin than on any other finding.
What a routine laboratory can say
A bench laboratory without trace-element analysis can note inclusion features consistent with a source, and should say no more. It cannot responsibly certify origin, and a report that does so without chemical analysis is overstating what was done. For most stones and most buyers, identity and treatment — which a bench laboratory can determine — matter far more than origin.
For Rudraksha, the equivalent question is Himalayan versus Indonesian, answered from size and surface characteristics, and likewise an opinion. Nepal vs Indonesian (Java) Rudraksha.
What to make of an origin claim
An origin stated on a seller's description is a claim. An origin opinion on a report from a laboratory with chemical analysis, expressed with appropriate qualification, is evidence. Two such reports agreeing is stronger evidence. A premium paid for origin should rest on the latter, never the former.
Frequently asked questions
Can origin be proven?
No. It is inferred from characteristics, with a degree of confidence. "Proven" origin does not exist.
Does origin affect anything other than price?
Not the stone's properties. A ruby from Mozambique is as hard, as durable and as red as one from Burma of the same quality. Origin is about rarity and prestige.
Why do labs disagree about origin?
Because the evidence is comparative and reference data differ between laboratories. Disagreement on origin is common and does not mean either laboratory is incompetent.
Can a routine gem report include origin?
It can note features consistent with a source. It should not assert origin without the instruments to support it, and buyers should ask what analysis was done.
Is "Ceylon sapphire" a species?
No. It is a trade name for sapphire from Sri Lanka. The word describes claimed origin, not the mineral, which is corundum wherever it grew.