Jade bleaching is the standard trade term for the chemical treatment in which lower-grade jadeite is acid-leached to remove iron-bearing inclusions, fractures and impurities, and then impregnated with a polymer (typically a paraffin wax in early treatments and an epoxy or polystyrene resin in modern work) to restore structural integrity and improve apparent translucency. The treatment is the principal concern of jadeite quality control in the modern trade and is the basis of the B-jade and B+C jade trade categories.

Process

The treatment was developed in Hong Kong in the late 1980s and entered widespread commercial use through the 1990s. The standard procedure begins with the selection of low-grade jadeite rough, usually with poor colour distribution, surface staining or visible iron oxide impurities. The rough is cut to near-finished form and immersed in concentrated hydrochloric or other acid for a period ranging from days to weeks, which dissolves out iron-bearing impurities and leaves a network of micro-fractures along the original grain boundaries. The leached stone is then dried and impregnated under vacuum and pressure with a clear polymer that fills the leached network, restoring the structural integrity and producing a uniformly translucent finished cabochon or bangle. Dyeing (the addition of organic colorants) is sometimes performed in the same impregnation step, producing the B+C jade category.

Trade categories

The Hong Kong, Chinese and GIA trade recognise four categories: A-jade is untreated jadeite (with conventional waxing of the surface, considered acceptable in the trade and not classed as a treatment). B-jade is bleached and polymer-impregnated. C-jade is dye-treated without impregnation (a less common category, since dye without impregnation is unstable and tends to fade). B+C jade is both bleached, impregnated and dyed. Only A-jade is acceptable in the high-end traditional Chinese trade, and the price differential between A and B+C for fine-looking finished cabochons is typically 100 to 1 or greater.

Detection

The principal detection methods for B-jade are infrared (FTIR) spectroscopy, which shows the C-H stretching bands of the polymer in the 2800 to 3000 cm⁻¹ region, and Raman spectroscopy, which detects the polymer's characteristic Raman shifts. Long-wave ultraviolet fluorescence is a useful screening tool: untreated jadeite is generally inert to weakly fluorescent, while polymer-impregnated material often shows a milky-blue chalky fluorescence. Microscopic examination at twenty- to forty-power magnification reveals the leached granular surface beneath the polymer fill, and the polymer layer itself often shows fine subsurface bubbles or a characteristic slightly resinous lustre. Specific gravity is reduced by polymer impregnation but the difference is small and not diagnostic on its own. The GIA, GIT, NGTC and HRD all issue jadeite reports distinguishing the treatment categories, and a laboratory report from a recognised house is the standard requirement for any high-value jadeite transaction.

Stability and disclosure

The early-generation paraffin wax and polystyrene impregnations have shown progressive yellowing and structural failure over twenty to thirty years, and B-jade pieces from the 1990s are now starting to fail in the secondary market. Modern epoxy-resin impregnations are more stable but still subject to long-term degradation. CIBJO Blue Book rules require disclosure of treatment status at every level of the trade, and FTC Jewelry Guides in the United States and equivalent codes in the UK, EU, Hong Kong and China require equivalent disclosure at retail.