Ask your fiancee if she'd like her wedding ring to be made using a Samurai swordmaking technique, and you'll probably get a resounding "No;" you might as well ask her if she'd like the ceremony to be performed by ninjas. But metalworker James Binnion has researched a rather unusual metalworking technique used by Japanese swordcrafters, and adapted it to make very unique jewelry.
Mokume gane is a metal working technique developed in Japan approximately three to four hundred years ago, in which two or more layers of metal are permanently joined together in alternating layers to form a stack (or billet). In the traditional Japanese technique the bond was achieved by diffusion welding of the layers in a charcoal forge. On this laminated billet patterns of the different colored alloys were created by a combination of cutting, twisting, and forging of the laminate in ways to expose the various layers. The patterned billet was then formed into finished work by applying standard forging and fabrication techniques.
Binnion's update on the process has him clamping anywhere from 10 to 30 different layers of metal together and laminating them in an electric kiln. The resultant billet, in which the layers are "diffusion bonded"--fused together but not melted--is then repeatedly forged, carved and rolled.
Binnion wrote a paper on the technique for a jewelry manufacturing technology conference, available for free download here, and you can check out what he's capable of producing here.