What N, H, E, D, U, C, F, R, B, O, W and the rest actually mean, why disclosure is not optional, and how to record treatment so it survives the whole life of the stone.
· 9 min read · By Nveloop
Every stone that has been altered after it came out of the ground has to be disclosed, every time it changes hands. Not because a regulator will catch you — often nobody will — but because the trade only functions on the assumption that everyone else is telling the truth, and the moment that assumption breaks, prices break with it.
The colored stone trade codifies this with a set of single-letter treatment codes, most widely through the American Gem Trade Association's system. They are short enough to print on a memo, an invoice or a label, and precise enough that a buyer in another country knows exactly what they are being offered.
The stone has been cut and polished and nothing else. No heat, no filling, no irradiation, no coating. For sapphire and ruby this is the single most valuable word in the trade: an unheated Ceylon blue sapphire with a laboratory report confirming no indication of heating routinely sells at a multiple of the same stone heated.
Controlled heat used to improve colour or clarity. It is the most common enhancement in corundum by an enormous margin, it is stable and permanent, and it is entirely accepted — provided it is disclosed. Sub-codes are used where the heating involved additives: H(a) for heating with minor residue in fissures, H(b) for heating with a glass-like residue, H(c) for lattice diffusion of a colouring agent, and H(d) where diffusion has produced an artificial asterism or colour layer.
Used where a treatment is so traditional for that species that the trade assumes it. Emerald oiling is the classic case: cedar oil in fissures has been standard practice for centuries, and a completely untreated emerald of any size is unusual enough to be remarkable.
A surface layer applied to change colour or apparent quality. It is not durable in the way heating is; it can be damaged by ultrasonic cleaning, steam, abrasion and some solvents. Disclosure matters here as much for care instructions as for value.
Colouring agent introduced into a porous stone or into fissures. Common in some jadeite, in porous chalcedony and in low-clarity material. Stability varies enormously with the dye and the stone.
Glass, resin or a similar material introduced into fractures or cavities to improve apparent clarity. Lead-glass-filled ruby is the best-known example and the most contentious: at high fill percentages the material is arguably a composite rather than a treated ruby, and it should never be priced or represented as the latter.
Colour or asterism introduced into the surface layer of the stone at high temperature. Depending on depth, a recut can remove some or all of the effect — which is exactly why it must be disclosed.
Colour altered by exposure to radiation, sometimes with subsequent heating. Standard for some blue topaz and some coloured diamonds. Colour stability under light and heat varies by material and should be checked before you commit.
Chemical lightening, often used in combination with impregnation. Frequently seen in jadeite, where bleaching followed by polymer impregnation produces what the trade calls B-jade.
Colourless oil, wax or resin in surface-reaching fissures to reduce their visibility. Standard practice in emerald; graded by degree, from insignificant to significant, by most laboratories.
Impregnation of porous or opaque stones such as turquoise, lapis or some jadeite, to improve polish and appearance.
Almost nobody in the trade sets out to conceal treatment. Disclosure fails for a much more ordinary reason: the information is recorded once, on a packet or in a notebook, and then the stone travels. It gets recut, put on memo, sent to a lab, returned, sold, resold — and somewhere along that path the treatment note stops travelling with it.
The disclosure problem is not an ethics problem. It is an inventory problem wearing an ethics costume.
Which is why treatment belongs in the stone's permanent record rather than on its packet. In the Gem Merchant System treatment is a first-class field on the stone, alongside variety, colour, origin and certificate. It follows the stone through cutting, lab submission, memo and sale; it prints on the label and appears on the invoice; and when the stone is published to your website, it appears on the listing without anyone having to remember it.
Get that right and disclosure stops being something you have to remember. It becomes something the system cannot forget.
Treatment code systems are maintained by trade bodies and are revised from time to time; laboratories also differ slightly in the wording of their conclusions. Use the codes as trade shorthand, and let the laboratory report be the authority. Where the two ever disagree, the report wins — and both belong in the stone's record.
Why stock books and spreadsheets stop working at about four hundred stones, what a gemstone inventory record actually needs to hold, and how to get from a shoebox of packets to a system you trust.
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