Lusterware or Lustreware (respectively the US and all other English spellings) is a type of pottery or porcelain with a metallic glaze that gives the effect of iridescence, produced by metallic oxides in an overglaze finish, which is given a second firing at a lower temperature in a `muffle kiln`, reduction kiln, which excludes oxygen. ==Ancient..... Found on http://en.wikipedia.org/wiki/Lusterware