What makes Mulberry silk so expensive Mulberry Silk is 100% Natural, Odorless, and Hypoallergenic. Mulberry silk contains a natural protein that reduces the possibility of an allergic reaction. Mulberry silk is the highest quality silk and also the most expensive type of silk you can purchase. Natural color, non-dyed, no chemical, super soft, and friendly to all skin types Wash by hand in the cold water.