Michael Bradley reports that a superb jade bangle, with an interior diameter of 49.50 mm and 8.36 mm thickness, sold in 1999 for $2,576,600 at Christies. The obvious problem is that the character of a gemstone can be enhanced (or even produced ab initio) by non-natural methods. In cases where such enhancement is disclosed, this is not a problem, although the stone value is not as high as that of a totally natural example. Jade is actually two minerals, jadeite and nephrite, jadeite being the more rare and valuable.
Today, there are three classes of jadeite jade which differ in value, one of which is chemically treated and resin impregnated to enhance its translucency. Fraud is a major concern. There are three classes of jadeite jade now commonly available. A grade jade is totally natural (jadeite), and has the highest true market value. The B material has been treated as discussed below, and C grade material has been artificially color enhanced. Typically, C jade is fairly easy to spot, but the treatments applied to B materials are more subtle. B jade starts as raw jadeite with brown or black stains. The jade is soaked in strong mineral acids to remove the stains, which also weakens the stone by leaching out some structural materials (mostly metallics like sodium). The pores generated are filled with a melted wax or polymer resin whose index of refraction closely matches that of jade. A hardener may be applied to the outside of the jade to seal the stone.
Besides the issue of potential fraud, the B treatment has several long-term issues, like skin burns from residual acid have been reported, and discoloration of the epoxy resin can occur. All of this underscores the need for a rapid and sensitive analysis method. B grade samples are often uniform in color and translucent. Green jade is the main example, but pink and yellow B jade has recently appeared. Normal gemstone analyses showed B jade was jadeite jade and not color-enhanced C jade.
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