Someone told me  WHEN YOU FIND PLATINUM ITS  usually stamped PT PLAT  or Platinum and sometimes with purity 850 900, 950 or  1,000. A JEWELRY PIECE OF PLATINUM IS WORTH MORE THEN GOLD OF EQUAL SIZE,   GOLD can be  31%  and usually not higher then 18K = 75% GOLD   PLATINUM purity could be stamped  850, 900. 950 OR 999.