The title of the most expensive and exclusive fabric in the world typically belongs to rare luxury animal fibers such as vicuña wool, genuine shahtoosh (derived from the endangered Tibetan antelope and strictly regulated), and ultra-fine varieties of grade-certified Cashmere or Mulberry silk. Vicuña wool commands exorbitant prices—costing thousands of dollars per yard—due to the extreme rarity of the high-altitude South American camelid, government-protected shearing regulations, and the extraordinary fineness and warmth of its lightweight fibers.