Bleached
Bleaching uses chemicals such as hydrogen peroxide or chlorine bleach to lighten, even out or remove colour. Bleaching may affect the material's durability.
On this page
Naming rule
- Naming rule
- Bleached [material name]
- Market differences and mutual recognition
- For pearls the two codes pull apart. GB/T 16552 lists bleaching as an optimization and only calls it a treatment when combined with filling; the CIBJO Pearl Book 2024 §4.5.2.2 instead puts bleached cultured pearls among those needing a specific treatment declaration at the point of sale. FTC §23.23 gives pearls the same three conditions that §23.24 gives gemstones.
Gem treatments compares how every treatment on this site is named and what each must disclose.
Where the treatment acts (schematic)
Chemical bleaching (hydrogen peroxide, chlorine bleach etc.) to lighten, even out or remove colour.
- Unbleached cultured pearl (cross-section)
- Shell bead nucleus
- Dark organic compounds (schematic)
- Hydrogen peroxide solution
- Fluorescent illumination
- Nacre after bleaching
If you reuse this animation, please credit LumaLark Wiki and link to this pageLicense: CC BY 4.0
Scene-by-scene transcript (4 scenes, with sources)
The caption of each scene in the animation above (the first scene lists its three panel captions), with sources.
Scene 1Bleaching (akoya cultured pearl as the example)
Before: Akoya cultured pearls that have not been bleached or brightened come in various colours.
During: The cultured pearls are immersed in a heated hydrogen peroxide solution combined with fluorescent illumination.
After: Bleaching acts on the pigments and dark organic compounds within the pearl, lightening the colour and making it more uniform.
Treated zone: pigments and dark organic compounds in the pearl
Sources
- From Single Source to Global Free Market: The Transformation of the Cultured Pearl Industry, by Russell Shor (Gems & Gemology, Fall 2007, Vol. 43, No. 3)
- Optical Whitening and Brightening of Pearls: A Fluorescence Spectroscopy Study, by Chunhui Zhou et al. (Gems & Gemology, Summer 2020, Vol. 56, No. 2)
- Identification of "Pistachio" Colored Pearls Treated by Ballerina Pearl Co., by Chunhui Zhou et al. (Gems & Gemology, Spring 2016, Vol. 52, No. 1)
- Chart of Commercially Available Gem Treatments, by Christopher P. Smith and Shane F. McClure (Gems & Gemology, Winter 2002, Vol. 38, No. 4, pp. 294–300)
Scene 2Process conditions
The cultured pearls are immersed in a heated hydrogen peroxide solution combined with fluorescent illumination. In the text's words, this usually involves immersing the cultured pearls in dilute hydrogen peroxide under low heat in controlled lighting conditions, and virtually all akoya cultured pearls are bleached to improve whiteness. Traditional processing starts with maeshori (immersion in a solvent for cleaning, originally done before bleaching to make it more effective); after bleaching some pearls are treated with an additive for the slightly pinkish overtone seen in many akoyas, and tumbling to improve lustre comes last.
Scene 3How it works
Bleaching removes, or reduces the concentrations of, the colour-causing pigments within pearls, while optical brighteners add an artificial optical effect: the two mechanisms differ. Nacre is made of overlapping aragonite platelets with organic conchiolin between the layers; a study of treated black pearls reasons that the organic pigments are present between the aragonite platelets. In GIA bleaching tests on two thin pieces of black-lipped oyster shell, light brown areas, especially at the edges, turned silver-white, confirming that hydrogen peroxide can oxidize the pigment compounds.
Sources
- Optical Whitening and Brightening of Pearls: A Fluorescence Spectroscopy Study, by Chunhui Zhou et al. (Gems & Gemology, Summer 2020, Vol. 56, No. 2)
- Identification of "Pistachio" Colored Pearls Treated by Ballerina Pearl Co., by Chunhui Zhou et al. (Gems & Gemology, Spring 2016, Vol. 52, No. 1)
- Identification of "Chocolate Pearls" Treated by Ballerina Pearl Co., by Wuyi Wang et al. (Gems & Gemology, Winter 2006, Vol. 42, No. 4)
Scene 4After treatment and how it is detected
Bleaching acts on the pigments and dark organic compounds within the pearl, lightening the colour and making it more uniform. How deep it reaches may be limited by penetration: in laboratory bleaching experiments on Tahitian cultured pearls, simple bleaching could not effectively modify the bodycolour, possibly because the bleaching liquid could not penetrate and disperse into each layer of nacre, the authors suggest.
Typically bleaching is not detectable; because it is hard to prove a pearl's exposure to chemicals such as hydrogen peroxide, bleaching is considered an 'acceptable' pearl treatment. A chalky, powdery appearance under long-wave UV is more commonly observed in akoya and freshwater cultured pearls, which are routinely bleached, and bleaching may make the fluorescence stronger, but these are only indications. Sometimes excessive bleaching might make some pearls more fragile. The CIBJO Pearl Book (2024 edition) lists bleaching among the treatments that require specific information to be declared at the point of sale.
Sources
- Identification of "Pistachio" Colored Pearls Treated by Ballerina Pearl Co., by Chunhui Zhou et al. (Gems & Gemology, Spring 2016, Vol. 52, No. 1)
- Optical Whitening and Brightening of Pearls: A Fluorescence Spectroscopy Study, by Chunhui Zhou et al. (Gems & Gemology, Summer 2020, Vol. 56, No. 2)
- Chart of Commercially Available Gem Treatments, by Christopher P. Smith and Shane F. McClure (Gems & Gemology, Winter 2002, Vol. 38, No. 4, pp. 294–300)
- From Single Source to Global Free Market: The Transformation of the Cultured Pearl Industry, by Russell Shor (Gems & Gemology, Fall 2007, Vol. 43, No. 3)
- Gemstone Enhancement and Its Detection in the 2000s, by Shane F. McClure, Robert E. Kane and Nicholas Sturman (Gems & Gemology, Fall 2010, Vol. 46, No. 3)
- A Study on Improving the Surface Appearance of Low-Quality Pinctada maxima Bead Cultured Pearls, by Nanthaporn Nilpetploy et al. (GIA News from Research, 2021)
- GIA Gem Encyclopedia — Pearl Care and Cleaning Guide
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
How the naming authorities record it
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| Column | Value |
|---|---|
| Description | Chemical bleaching (hydrogen peroxide, chlorine bleach etc.) to lighten, even out or remove colour. |
| GIA code | B |
| LMHC number / note | B (CIBJO Gemstone Book 2022 Annex B, clause 7.2: Bleaching); LMHC has no matching Information Sheet |
| GB/T category | Optimization (GB/T 16552-2017 §5.4.1 Table 1: bleaching is classified as optimization, remark cell empty; the combined method “bleaching and filling” is classified as treatment; representation method at §5.4.2.1/§5.4.2.2). |
| CIBJO disclosure requirement | CIBJO Gemstone Book 2022 §5.9 defines Bleaching. CIBJO Gemstone Book 2022 §4.2.5.2 sets out the disclosure method (trade code B per Annex B, clause 7.2). |
| FTC regulatory citation | §23.24 general rule: disclosure is required if the treatment is not permanent (a), creates special care requirements (b), or has a significant effect on value (c). §23.24 names no individual treatment, so Part 23 does not say which of (a)–(c) bleaching meets. For pearls and cultured pearls, §23.23 sets the same three conditions. |
| RAL / German declaration | No public source text: RAL 560 A5 is a paid document not on file on this site, so no RAL/DGemG wording is shown (unchecked) |
| JJA/AGL (Japan) treatment disclosure | JJA/AGL 2025 §1-2-1 lists bleaching (item ⑥) among the treatments applied to natural stones; §2-1-1: the treatment is to be stated to the extent it can be known. |
| AGTA code | B — heat, light and/or other agents used to lighten or remove colour (GIM 17th ed., p.V). Consumer disclosure must be in plain language; codes alone are not sufficient (p.III). |
| Gem-A position | The Gem-A By-Laws have no bleaching-specific rule. §7.e.iii: before purchase the buyer should be told if the stone is known to have been treated and, where relevant, how that may affect its durability; §7.b: CIBJO guidelines and definitions are taken as best practice. |
| Naming rule | Bleached [material name] |
| Disclosure requirement | Bleaching may affect the durability of the material. Codes differ on whether routine pearl bleaching needs its own declaration (compare the rows on this page); chemical bleaching that changes the structure, or bleaching followed by impregnation, must be disclosed. |
| Typical materials treated | Pearl (routine Akoya bleaching), coral (bleached gold coral), ivory |
| Market differences and mutual recognition | For pearls the two codes pull apart. GB/T 16552 lists bleaching as an optimization and only calls it a treatment when combined with filling; the CIBJO Pearl Book 2024 §4.5.2.2 instead puts bleached cultured pearls among those needing a specific treatment declaration at the point of sale. FTC §23.23 gives pearls the same three conditions that §23.24 gives gemstones. |
Materials on which it is recorded
How lab reports word it, by material
The standard report wording (LMHC) for this treatment is set out on these entries and sections:
The laboratory testing page's LMHC index lists every LMHC information sheet on report wording.
CIBJO definitions
- Bleaching
to remove or alter a colour by means of chemical or physical agents or light. See clause 4.2.5.2.
CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §5.9, p.21
to remove or change a colour by means of chemical and/or physical agents or light.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.25, p.24
to remove or alter a colour by means of chemical and/or physical agents or light.
CIBJO Blue Book — Coral Book (Coral Commission 2024) (CIBJO): §5.11, p.11
The books word this differently; each wording is given with its source.
Definitions are quoted verbatim from the cited CIBJO Blue Book; […] marks an excerpt, and the full definition is at the cited clause.
Materials listed for this method in GB/T 16552-2017 Table B.1
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| Material (row) | Method | Effect | Category |
|---|---|---|---|
| Feicui, Jadeite | Bleaching and filling | Changes appearance | Treatment |
| Quartzite jade | Bleaching and filling | Changes appearance | Treatment |
| Natural Pearl | Bleaching | Improves appearance | Optimization |
| Cultured Pearl (Pearl) | Bleaching | Improves colour and other aspects of appearance | Optimization |
| Coral | Bleaching | Improves appearance | Optimization |
| Ivory | Bleaching | Improves appearance | Optimization |
| Mammoth Ivory | Bleaching | Improves appearance | Optimization |
JJA/AGL table entries relating to this treatment
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| Gem name | Colour | As written in the table | Entry on this site | Page |
|---|---|---|---|---|
| Tiger's Eye | yellowish brown, brownish golden yellow | bleaching | Tiger’s Eye | p.11 |
| Coral | white | bleaching | Coral, White Coral | p.13 |
| Coral | brownish yellow | bleached black coral | Coral, Golden Coral, Black Coral | p.13 |
Other treatments
Sources
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| Authority | Document | Version | Clause | Source |
|---|---|---|---|---|
| GB/T | GB/T 16552-2017 | 2017 | §5.4.1 | Source |
| GB/T | GB/T 16552-2017 | 2017 | Table 1 | Source |
| GB/T | GB/T 16552-2017 | 2017 | §5.4.2.1 | Source |
| GB/T | GB/T 16552-2017 | 2017 | §5.4.2.2 | Source |
| CIBJO | CIBJO Gemstone Book | 2022 | §5.9 | Source |
| CIBJO | CIBJO Gemstone Book | 2022 | §4.2.5.2 | Source |
| CIBJO | CIBJO Gemstone Book | 2022 | Annex B, clause 7.2 | Source |
| FTC | 16 C.F.R. Part 23 | §23.24 | Source | |
| FTC | 16 C.F.R. Part 23 | §23.23 | Source | |
| JJA/AGL | JJA/AGL definitions and nomenclature for gems (Japanese-language document, no official English title) | issued January 2015, revised November 2025 | §1-2-1 | Source |
| JJA/AGL | JJA/AGL definitions and nomenclature for gems (Japanese-language document, no official English title) | issued January 2015, revised November 2025 | §2-1-1 | Source |
| AGTA | AGTA Gemstone Information Manual | 17th edition, August 2026 | p.V (B) | Source |
| AGTA | AGTA Gemstone Information Manual | 17th edition, August 2026 | p.III | Source |
| Gem-A | Gem-A By-Laws §7 Code of Practice (Gem Code) | 2009 revision | §7.e.iii | Source |
| Gem-A | Gem-A By-Laws §7 Code of Practice (Gem Code) | 2009 revision | §7.b | Source |
What the eye can and cannot tell
Two materials can arrive looking golden: naturally golden coral, and black coral whose bleaching produced a golden appearance. Colour alone separates neither, so the cause of colour has to be identified rather than read off the surface, and bleaching of black coral must be disclosed.
Jadeite that was bleached and then polymer-impregnated is B jade under Chinese practice.
What to ask for on the report
Under FTC rules the pearl provision sits at §23.23. GB/T 16552 Table 1 treats bleaching as optimization but classifies bleaching and filling combined as treatment. For jadeite, then, the question to ask is whether polymer impregnation followed: if it did, the goods are B jade.
Before you buy: what to check
Work through these in order before paying. None of them replaces a laboratory report; they decide whether you need one.
Two materials can arrive looking golden: naturally golden coral, and black coral whose bleaching produced a golden appearance. Colour alone separates neither, so the cause of colour has to be identified rather than read off the surface, and bleaching of black coral must be disclosed.
Jadeite that was bleached and then polymer-impregnated is B jade under Chinese practice.
- Under FTC rules the pearl provision sits at §23.23. GB/T 16552 Table 1 treats bleaching as optimization but classifies bleaching and filling combined as treatment. For jadeite, then, the question to ask is whether polymer impregnation followed: if it did, the goods are B jade.
- Bleaching may affect the durability of the material. Codes differ on whether routine pearl bleaching needs its own declaration (compare the rows on this page); chemical bleaching that changes the structure, or bleaching followed by impregnation, must be disclosed.
Questions about this treatment?
Disclosure practice for this treatment differs between authorities and markets, and a report does not always say what was done.