Cone 6: Oyster is a variegated cream/brown glaze that exhibits gray/purple undertones and breaks brown. Cone 10: Color changes to a variegated brown/cream. Increased movement. TIP: If your kiln fires cool, the glaze finish may be brown. An iridescent finish may be achieved by re-firing or if your kiln fires hot. If you like Green Tea and Capri Blue combos, then try oyster because these three glazes are in the same glaze family.