Silk Jersey items may be hand or machine washed up to 40°C (delicate cycle) using a mild silk detergent. All colours especially strong ones should be washed separately, especially the first few times to remove loose dye. Short spin and do not tumble dry. Warm iron on the reverse side of the garment if necessary. There is no doubt hand washed items last longer, however with care machine washed items will last reasonably.
Silk is a natural fabric, it has to be dyed to gain a colour other than Ivory. It is inevitable that there will be some dye loss in washing.