Most of us may not be familiar with this type of color enhancement on jadeite jade, especially for jade carving pendants, bangles, jade beads or figurines. I trawled the net intensively and I could not find any references to this type of enhancement. This type of color enhancement has been practiced for a long time but just that no sellers would like to divulge this trade secret or has it been discussed on any forums.
As discussed in my previous posts Type A Jadeite Jade is the natural Jadeite Jade with no polymer impregnation. Type B and Type C Jadeite Jade are essentially the same. Type D Jadeite Jade is just a misnomer label and it is better to call them Jadeite Doublet. So I just called this type of enhancement as Dye Coating Jadeite Jade.
The picture above shows two doggy jadeite jade pendants carved out from the same stone. The picture at the back has been dye coated (though the pix may not be too clear).
A type of copper green powder is used to coat the surface of a jade piece. The coating may be done with a tumbler where corundum abrasives are placed inside together with the green powder. After tumbling the jade piece for a few hours the green powder will adhere to the surface crevices of the jade on a carving piece.
The coating can also be done with a wheel brush, a chamois or muslin buffs mounted on a pneumatic air grinder. The brush is dipped with the green powder and as the brush rotates at high speed the green powder will be coated onto the jade piece.
This type of coating may not be detected by FTIR scan as the green powder used is not of polymer material. The only means of detecting this type of coating is to use a high magnifying gems microscope whereby the coating can easily be seen as very minute particles of green sticking onto the jade. You may be able to see it with a 10X loupe if you scrutinize it carefully.
After the jade piece is being dye coated, the jade piece may then be coated with a fine layer of special whitish wax and finally the jade piece may be polished by buffing off any excessive wax. Note that this is not the candle wax, as candle wax can be peeled off easily.
This type of enhancement is a deceptive practice and buyers need to be careful that the jade piece is not being dye coated.