Palladium while I'm not saying some deception may well be going on as I have stated before gold filled items even new will rarely be plum due to the manufacting process, the karat sided part will be the only one to be polished as it's usually facing outwards or on view if you prefer while the base metal side will be hidden and so need no fine finishing, if the polisher has a heavy hand you can soon remove a fair amount of the gold leaving an even bigger percentage of base metals. While I'm sure there are those who do take advantage and do under karat the gold deliberately surely it's up to the volume buyers to check the actual karat and percentage of gold before buying and even more so before selling to the public.