Within the AGTA gemstone enhancement coding system, the letter B designates bleaching: the deliberate application of chemical agents — most commonly hydrogen peroxide or dilute acids — to lighten, neutralise, or entirely remove undesirable colour from a gemstone or organic material. The code appears on AGTA disclosure documentation and laboratory reports whenever bleaching is detected or disclosed, and its presence signals that the stone's colour or clarity has been altered by chemical rather than thermal or irradiative means. Bleaching is among the older and more widely accepted enhancement categories in the trade, yet it carries specific stability caveats that distinguish it from more durable treatments such as heat.

Materials Commonly Bleached

Three material categories account for the great majority of commercial bleaching.

• Cultured and natural pearls. Bleaching is virtually universal in the pearl industry. Freshwater and saltwater cultured pearls are routinely exposed to dilute hydrogen peroxide solutions to even out skin tone, reduce yellowish or greyish overtones, and produce the bright white body colour that the market has come to expect. The treatment is so pervasive that GIA and most major laboratories consider it a standard, accepted practice for cultured pearls and do not penalise stones for it on grading reports, though AGTA standards still require its disclosure.
• Jadeite jade. Bleaching is the first stage in producing what the trade calls B-jade (or B+C jade when dyeing follows). Natural jadeite frequently contains brown or yellowish iron-oxide staining along fractures and grain boundaries. Immersion in acid solutions — typically hydrochloric or oxalic acid — dissolves these oxidation products, leaving a cleaner, paler matrix. This bleached material is then almost invariably impregnated with polymer resin to restore structural integrity lost during the acid treatment. The combination of bleaching and impregnation is the defining characteristic of B-jade and must be disclosed; it is distinguished from untreated A-jade by infrared spectroscopy and other laboratory methods.
• Coral. Precious coral — particularly Corallium rubrum and related species — is occasionally bleached to lighten overly dark red or pink material, or to produce white coral from naturally pigmented stock. The treatment is less standardised than pearl bleaching and is viewed with greater scepticism by the trade.

Chemical Agents and Process

Hydrogen peroxide is the most widely used bleaching agent across all three material categories; its oxidising action breaks down organic chromophores responsible for yellowish or brownish tints. For jadeite, mineral acids perform the additional function of dissolving iron hydroxide deposits from within the stone's interlocking crystal structure. Treatment times range from hours to several days depending on the degree of staining and the concentration of the solution. The process is conducted at controlled temperatures; elevated heat accelerates bleaching but increases the risk of surface damage, particularly in pearls, where nacre layers are thin and structurally delicate.

Stability and Durability

Bleaching is generally described as permanent under normal wearing conditions, but it is the least stable of the major enhancement categories in certain respects. Prolonged exposure to strong light — particularly ultraviolet — can cause re-yellowing in pearls, as residual organic compounds within the nacre continue to oxidise. Harsh cleaning chemicals, including chlorine bleach and ultrasonic solutions, may accelerate this process or cause surface damage. In B-jade, the long-term concern is not the bleaching itself but the stability of the polymer impregnation that follows it: resins can yellow, crack, or degrade over decades, and the stone's surface hardness and lustre may change accordingly. Owners of bleached pearls are advised to store them away from prolonged direct sunlight and to have them restrung periodically, as the bleaching process can slightly weaken silk thread through residual chemical transfer.

Detection and Laboratory Identification

GIA identifies bleaching in jadeite through Fourier-transform infrared spectroscopy (FTIR), which reveals the polymer impregnation that invariably accompanies acid bleaching in B-jade. In pearls, bleaching is generally assumed for cultured material and noted rather than specifically tested for in most laboratory protocols. Raman spectroscopy and UV-visible spectroscopy can provide additional evidence of chemical alteration in organic gem materials. Because bleaching in pearls leaves few definitive spectroscopic signatures, laboratory reports for pearls typically note the treatment as standard practice rather than as a detected anomaly.

Disclosure and Trade Standards

AGTA requires disclosure of the B code whenever bleaching has been applied, regardless of how widely accepted the practice may be for a given material. This places bleaching alongside heat treatment, fracture filling, and irradiation as a category requiring affirmative disclosure at point of sale. In practice, disclosure norms vary by material: pearl dealers routinely disclose bleaching as a matter of course, while the distinction between A-jade and B-jade is a critical valuation issue — untreated A-jade commands substantially higher prices, and misrepresentation constitutes fraud in most jurisdictions. The AGTA coding system exists precisely to provide a standardised vocabulary for these distinctions across the supply chain.

Further Reading

• GIA — Jadeite Jade Treatments
• AGTA — Gemstone Enhancement Codes
• GIA — Pearl Quality Factors