Diamond Treatments: The History, the Catalog, and the Disclosure Law
Change log: Wave 4 first pass. Where wave 2–3 modules teach grading, this module teaches what grading must exclude: undisclosed alteration. It is M07’s twin.
The frame: three questions, every stone, always
- Has this stone been changed? (treatment)
- Is the change permanent and stable? (durability of the alteration)
- Was the change disclosed? (law and ethics — the only question you can guarantee to answer correctly for every stone you sell)
GIA’s own lab definition of the problem is one line from the 2013 chart (read verbatim): in natural diamonds, “defects can be altered over geologic time in the earth or by exposure to heat or radiation during color treatment.” Treatments are the engineered version of what geology already does; detection is the art of telling the two apart. Which, per the same paper, “is not always possible using standard gemological methods.”
The history you can cite (Overton & Shigley 2008, “A History of Diamond Treatments,” G&G 44:1)
Compressed from the title-level assignment (full read is on the to-do list; narrative is consistent with the handout’s framing — decade boundaries when quoting): 1950s–60s, laboratory irradiation (reactor and, per Schulke’s 1961 “Artificial Coloration of Diamonds,” salt-and-acid recipes) produces green/black colors and the first “treated diamond” scandals; 1980s–90s, HPHT annealing (turning many Cape-like yellows whiter, and some browns to colorless/green-yellow) and glass/filling (clarity disguise) industrialize; 1999–2000, GE POL (high-pressure-high-temperature treatment of fancy colors) arrives at scale, triggering the industry’s disclosure crisis — and the legal answer the literature then documents: Overton, “Gem Treatment Disclosure and U.S. Law” (G&G 40:2, 2004 — the FTC-rule paper). The A19 list is essentially the forensic record of each wave (irradiation, laser-drilling, filling and HPHT detection papers in the bibliography — every one of them is a wave’s aftermath).
The rule the history teaches: every treatment that ever mattered was commercially invisible before it was detectable. Detection methods (the lab literature) are the reaction, usually years behind. Pricing and policy that assume “treated stones are obvious” have been wrong every decade since 1959.
The catalog (with detection status, honestly labeled)
| Treatment | What it does | Detectability at the counter | Detectability in the lab | Report language |
|---|---|---|---|---|
| HPHT annealing (color) | Removes/brown→colorless, or yellow↔green shifts | Not detectable visually; subtle re-absorption of graining can happen | FTIR/UV-Vis/PL signatures; type logic (M08/M11) | “Color Treatment” comment on GIA report |
| Irradiation (± annealing) | Green rims→uniform green/blue/black | Rim zoning (M08) sometimes visible; not reliable | Spectroscopy | “Irradiated” / listed as color treatment |
| Fracture filling (glass) | Disguises fractures & laser drill-holes | Flash effect: orange/blue “pinked” sheen at low angle on a cleaned, dry stone; sometimes a whitish veil or gel-like residue — classic 10× finds | IR/UV-Vis; radiography for hole traces; detectable with standard lab instruments | “This stone has undergone clarity enhancement” (asterisk, per M07) |
| Laser drilling | Burns drill-holes to reach/remove a dark inclusion | Microscopic straight line + round hole at the surface, often feathery bleached residue; historically visible even naked-eye in parcels | Easily recorded, plot marks them | “Laser Drilling (or laser holes)” comment; older stones may say “drilled” |
| Coating (incl. thin-film, “Diamantine”) | Color-shifts or masks; on melee and faceted stones | Greasy luster, color pooling at girdle/facet junctions, abrasion marks; orange-flash of coated CZ (M10) | Microscopy + spectroscopy; interferometry for film thickness | “Coating”/”color added” comments — and reports may be refused for coating-heavy goods |
| Surface lattice diffusion (corundum/spinel analogy) | Color into skin layer only | Surface color pooling, facet-edge bleeding | Confirmed absent in diamond (cobalt diffusion is exclusive to spinel; diamond surface-color relies on coatings or irradiation) | Not applicable to diamond; “coated/treated” |
| Stress fracture / whitening, fracture braiding | Cosmetic surface tricks on low goods | Veil/whitening at 10× | Lab confirms | clarity-enhancement-family comments |
| Surface-conduction blue (IIb-like films) — watch for coated “blues” | fakes color | conductivity test can false positive on coated stones | lab | — |
Two bench-critical notes: (a) fillings survive most cleaning agents but not all — a steam cleaner can strip a temporary filler or open a filled fracture (standard bench caution; tie to your ultrasonic/steam policy — Kammerling et al. 1994’s durability tests on acid, heat and torch are the documented basis); (b) the loupe test for fillers is angle-dependent and light-dependent: tilt under diffuse light, look for the blue-orange “pinked” sheen that no natural film produces (McClure & Kammerling 1995, “A Visual Guide to the Identification of Filled Diamonds,” G&G 31:2 — the flash effects, blue/orange tint and lead-light reflections are that paper’s own subject).
The disclosure law (the one thing to memorize verbatim)
From the GIA handout’s framing of the 2004 FTC update (overton2004 — the paper’s own subject per its title): the U.S. Guides for the Jewelry Industry require disclosure of any treatment that is not permanent, can be damaged during routine care, or that significantly affects value. That three-clause structure is the operative test, and note its elegance: a permanent, harmless-to-care, value-neutral alteration is not legally mandatory to disclose — but GIA’s own report practice marks all treatments regardless (M07 asterisk), and a professional shop’s policy should be stricter than the floor the FTC sets. The lesson of GE POL is the other half of the record: the market re-prices undisclosed treatments violently when the public finds out (the 1999–2004 paper cluster documents the shock: Smith et al. “GE POL Diamonds: Before and After” G&G 36:3; Fisher & Spits’ independent spectroscopic detection — G&G 36:1, 2000; Schmetzer’s process reconstruction G&G 35:4, 1999; Overton 2004 on the law). Non-disclosure isn’t just wrong; it’s the most expensive mistake in this trade. (verbatim per 16 CFR § 23.24)
Practice: intake and floor
The five-sentence policy (adapt for shop signage, consistent with Prompt Kit D-discipline: never hide treatments from a customer): 0) Every treated stone is an opportunity to be the shop that knew first. 1) Every report-bearing stone enters at its report’s treatment comments. 2) Every loose stone without a report is screened as a possible treated good. 3) Any fracture-bearing stone (VS2 and below) is re-checked for filling at intake and at every cleaning. 4) Treatment findings change price, never the customer’s right to know: disclose first, then negotiate. 5) If it’s unclear, the lab decides — a $60–$120 grade is cheaper than one lawsuit.
Scripts. “Why is this one cheaper than the identical-looking one?” — because this one’s report lists clarity enhancement; that’s the whole difference in price — the stone’s beauty is real, its durability rules are different, and you’re getting that information now, not later. — and for the consignor side: “We screen for fillings every time we clean; if your stone has enhancement we’ll tell you and treat it differently in service — that protects the stone and your price.”
Self-check
- State the three-clause FTC disclosure test from memory.
- Which treatment has counter-visible signs and which are counter-invisible? (filling/laser: visible; HPHT: invisible) — and what does that predict about which one shows up in appraisal fraud?
- Name the GE POL lesson in one sentence.
- Why does the 2013 chart’s “altered by heat or radiation” sentence make M08 prerequisite for M12?
- Which report marks exist for treated stones (asterisk, comments, plot) and which documents refuse them (eReport — M07)?
- What is the correct response when a customer’s ring goes through your ultrasonic and a filled fracture opens? (disclose, document, offer lab review — and never blame the customer)
Further reading (A19, treatments block)
overton2004 + overton2008 (the policy pair — read together); the GE POL cluster (Smith et al. 2000; Fisher & Spits 2000; Schmetzer 1999); McClure & Kammerling 1995 + Kammerling et al. 1994 (fillings); McClure et al. 2000 (lasering); Nazz & Johnson 2013 (radioactive-salt greens); Fritsch & Shigley 1989 (zoning pattern-recognition). Full annotations in `references/`. Pair with M07 (report marks) and M08 (mechanisms).