Rose gold, yellow gold, platinum, stainless steel… wood? Better yet, bone?
Vjatka, Russia: In the early 1900’s, a small family of watchmakers became fascinated with the art of organic watchmaking and produced 500 wood, bone and ivory pocket watches over three generations. Approximately 250 of these horological creations still survive today, and are prized around the world. Most recently, a piece sold at a 2005 auction for $25,000 (a significant increase from its original price of 120 rubles). The original wooden model, first displayed in 1837, is said to have been purchased by Alexander II.
Source article: http://watchismo.blogspot.com