Keum-boo (also Kum-Boo or Kum-bu- Korean "attached gold") is an ancient Korean gilding technique used to apply thin sheets of gold to silver, to make silver-gilt. Traditionally, this technique is accomplished by first depleting the surface of sterling silver to bring up a thin layer of fine silver. Then 24 carat gold foil is applied with heat and pressure - mechanical gilding - to produce a permanent diffusion bond.