Mokume gane

Mokume gane is a mixed-metal laminate with distinctive layered patterns. Translating as burl metal, the name was borrowed from one type of pattern created in the forging of swords and other edged weapons.

First made in 17th-century Japan, the mixed-metal was used only for sword fittings until the Meiji era, when the decline of the katana industry forced artisans to create purely decorative items instead. The inventor, Denbei Shoami (1651–1728), initially called his product guri bori for its simplest form's resemblance to guri, a type of carved lacquerwork with alternating layers of red and black. Other historical names for it were kasumi-uchi (cloud metal), itame-gane (wood-grain metal), and yosefuki.

The traditional components were relatively soft metallic elements and alloys (gold, copper, silver, shakudo, shibuichi, and kuromido) which would form liquid phase diffusion bonds with one another without completely melting. After the original metal sheets were stacked and carefully heated, the solid billet of simple stripes could be forged and carved to increase the pattern's complexity. To achieve a successful lamination using the traditional process required a highly skilled smith with a great deal of experience.

The modernized process typically uses a controlled atmosphere in a temperature controlled furnace. Mechanical aids such as a hydraulic press or torque plates (bolted clamps) are also typically used to apply compressive force on the billet during lamination and provide for the implementation of lower temperature solid-state diffusion between the interleaved layers, allowing the inclusion of many nontraditional components such as titanium, platinum, iron, bronze, brass, nickel silver, and various colors of karat gold including yellow, white, sage, and rose hues as well as sterling silver.