Unfortunately, the majority of green jade on eBay is polymer treated, this is especially true of that coming from China.  Regardless of what the seller says, no one can realistically sell "Imperial" quality jade for the prices offered, unless it is treated.  Recently we purchased two items guaranteed as being untreated and natural color, subsequent lab testing resulted in both pieces, a $300.00 bead necklace as being dyed quartz and a $750.00 bracelet as being polymer treated.  Both pieces were being sold from locations here in the US.  Both sellers refunded the money without question.  Additionally, a seller who has a large number of green jade pieces cancelled our purchase of six pieces when we notified them that we were going to have them lab tested.  He offered no explanation just refunded the money.  With 35 years of experience buying and selling jade in San Francisco, I no longer try to buy quality jade on eBay.  This is not to say that there are no ethical sellers, it is just that the buyer has to be extremely careful.  Feedback is not an indication of authenticity, most buyers cannot afford or do not have access to the testing that is available to the trade so they accept the guarantee of the seller as gospel.  The problem is that if they attempt to sell the piece or have it appraised for insurance purposes they may have unhappy situations arise.  This glut of misrepresented jade as well as that purported to be antique is a shame and should be addressed by eBay and civil authorities but is obviously too huge a market to control, therefore the buyer must use common sense when buying such items.  Remember, fine quality green jade is extremely rare and expensive, so if someone is offering you Imperial quality at peasant prices then something is wrong, if it was real it could sell at auction or privately for much more.  Also, it should be obvious that antique jades were not made in vast numbers, so that if you see the same piece repeated or similar pieces selling over and over, a red flag should go up and the buyer should realize that it cannot be what it is said to be by the seller.  At the same time, if the buyer wants a fake, like a cubic zirconium, then they should enjoy the dyed or fake pieces, however, if you want quality jade, you really should look elsewhere or buy only from sellers you absolutely trust.