Silk Charmeuse is a natural fiber that needs special care. Hand washing is the best for smaller pieces like camisoles, dance pants, chemises and some nightgowns. For larger pieces like kimonos I suggest dry cleaning unless you are adept at ironing.
Hand wash separately with a small amount of washing liquid made specifically for intimate apparel and delicate fabrics. Do not soak for more than 20 minutes and scrub gently with your hands. Do not ring out, instead either lay the garment on a towel or hang on a hanger to allow most of the water to drip out then lay on a towel.
If you do not wish to iron you can smooth the garment out gently with your hands while it's on the towel. To iron use a medium heat being careful not to touch the lace with the item. You can iron the lace by using a pressing cloth.