A silk comforter is a long term investment. If you take good care of it, you will prolong the life of your silk comforter and be able to enjoy it for many years to come.
If you do need to clean a mulberry silk comforter, it must be professionally cleaned. Washing a silk comforter in water you would almost certainly ruin it. Make sure you call around and ask the cleaners about their experience with cleaning both comforters and silk. Often cleaners that specialize in cleaning silk bed sets are good candidates. Although dry cleaning is a possibility, there may be trace amounts of chemical residues left behind and the process may harden the silk if done repeatedly. Professional wet cleaning is becoming more common, and is the preferred option.
Silk comforters are made out of silk which is an amazing fiber in that it is remarkably strong, and yet very fragile, so find a professional to perform the cleaning.