Silk velvet. Silk thread woven into velvet was once so expensive, only royalty could afford it. It is still expensive today, averaging $200 per yard. Silk velvet has a lovely soft drape and a shimmering surface. The fabric is so soft that the nap crushes easily, leaving a mark or impression — a feature that identifies the velvet as being made of silk. For this reason, never iron silk velvet, as it will crush the fibers and leave an imprint that often cannot be removed.