well i remember reading about this a little while ago and though it applied. Damien Hirst made a cast of a human skull out of platinum and covered it in diamonds and it is worth $100 million dollars.

there is a post on another blog on the step by step process with pictures of how the skull was made

http://www.supertouchblog.com/2007/07/21/techniquethe-making-of-damien-hirsts-diamond-skull/