Almost every risk in buying jadeite reduces to one question: has the stone been altered, and was that disclosed? The A/B/C system exists to answer it.
Treatment categories
| Type | Treatment | Stability | Disclosure |
|---|---|---|---|
| A | None. Cutting and polishing only; surface waxing may be present | Stable | No disclosure needed beyond stating Type A |
| B | Bleaching with acid, then polymer impregnation | Can degrade over years | Must be disclosed |
| C | Dyeing to introduce or intensify colour | Colour may fade | Must be disclosed |
The categories are not quality grades. A Type B stone with beautiful colour is still a Type B stone, and it should be priced and described as one.
How a laboratory distinguishes them
Visual inspection under magnification
Bleaching leaves tell-tale surface structure; dye concentrates in cracks rather than following the grain.
Refractive index and specific gravity
Polymer impregnation shifts the stone's density measurably.
Spectroscopy
Dyes show absorption features that untreated jadeite does not.
Ultraviolet fluorescence
Some polymers fluoresce where natural jadeite does not.
A certificate is not a promise. It is a record of what a laboratory observed on a particular day.