Dear Ross, Thank you very much for your circumstanciated reply.As far as the practice of oiling shells is concerned, I can accept it if it preserves the periostracum that might have a tendency to peel off after some time in rather dry conditions.I can also understand conchologists who like to use make up ( oil)to enhance the colors. But is there scientific evidence that the oil otherwise " preserves" as you state it. If so, I would like to hear about that evidence from you or anyone who might have it.I suppose any shell has a quantity of H2O in it. Does oil prevent the water to evaporate? Should we prevent water to evaporate? Does oil prevent colours to fade away? I further reviewed some posts and read with lots of interest one dedicated to lip filing in conus and other shells. My question at this stage of the discussion is: is there any means of finding out by simple observation whether a shell with a natural gloss (cypraea, oliva, marginella and even some conus) has been enhanced by means of polishing powders? Best regards Charles