There has been a proliferation of sellers offering COA's or Certificates of Authentication for the pieces they are selling, this has been especially true of so called "antique jade".  Ebayers should consider that if the seller is offering such a document does it really mean that the piece of Han jade, or Warring States jade is authentic just because such a document is sent along with the piece.  The reality is that in most cases such documents are not worth the paper they are written on.  After all anyone can write such a document regardless of their qualifications.  This is especially true if you see the same seller offering more than one of the same "antique" piece.  Common sense should make you aware that you cannot buy a two thousand year old piece of jade for .99 cents, especially from China.  Being a dealer in such items, the biggest buyers of antique pieces of this type are the Chinese themselves.  So much of their patrimony or fine antique pieces were looted in the last one hundred years that they are buying them back at very high prices so to think that such valuable pieces are so available and at such ridiculously low prices is almost laughable.  I do not even have to touch the pieces to be able to tell that they are fake, the material used and the way they are carved gives them away immediately to anyone who has any excperience in dealing in this type of merchandise.  Also, if you read the fine print, even though the sellers offer to accept the items back, in most cases it does not include shipping charges and there is usually a "restocking" fee.  This is a classic case of buyer beware.