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Eurojade - Le Spécialiste du Jade - The Jade Specialist


Jadeite historically has been subjected to various enhancements to "finish" it, "clean" surface and interior stains, and even dye it to change the colour altogether. In recent years, a three-part - A through C - classification system has been used in Hong Kong and elsewhere to designate the treatment to which an item has been subjected.

A-Jade is jadeite that has not been treated in any way other than cutting and polishing. Surface waxing is generally considered part of the "traditional" finishing process. Used to improve luster and fill surface fractures and pits, wax dipping is the final step in finishing virtually all cut jadeite.

A process commonly used to enhance polished jadeite, waxing (or "wax dipping") is actually a simple procedure. First, the bangles are soaked in a warm alkaline solution about 5-10 minutes to clean the residue left behind during polishing. Next they are rinsed, dried, and then soaked in an acidic "plum sauce" to remove any residue from the alkaline solution. Then, they are rinsed, dried, and placed in boiling water for several minutes to open the "pores" in the jadeite and bring it to the right temperature (to avoid cracking) before it is placed in a pre-melted wax solution for several minutes to several hours After waxing, the items are polished with a clean cloth to reveal their best luster.

As noted above, much jadeite is discolored by rust-like oxydation stains. B-Jade is jadeite that has been soaked in chemical bleaches and/or acids for an extended period to remove brown or yellow impurities from between grain boundaries and cracks. Because this treatment process leaves voids in the jadeite, the bleached jadeite is subsequently impregnated with paraffin wax or, most commonly, a clear polymer resin.The result is usually a significant improvement in both transparency and colour. However, detection of this enhancement generally requires infrared spectroscopy, a sophisticated technique that usually must be performed in a gemological laboratory (see Fritsch et al., 1992, for a full description of both the treatment and its identification). In some B-jade, resin-filled areas can be seen under the microscope in reflected light.

C-Jade, jadeite that has been artificially stained or dyed, also has a long history. Green, lavender, and even orange-brow colours are produced by staining suitable pale-coloured material with vegetable or other organic dyes, a process that has been performed on jadeite since at least the 1950s. The methods used in Hong Kong have been described by Ehrmann (1958), Ng and Root (1984), and Ho (1996).

The authors have seen fading in both dyed green and dyed lavender jades, but the green dyes tend to fade more readily. Generally, dyeing is identified with a microscope and a spectroscope : the colour tends to concentrate in veins throughout the stone, in surface cracks, and along grain boundaries; also, a broad band from about 630 to 670 nm in the red region of the visible spectrum is considered proof of dye in green jadeite (see, e.g., Hobbs, 1982). Some of the newer dyes may also show a weaker band.