If you are determined to buy a silk filled quilt with silk casing, then keep reading us now.
Generally speaking, every silk duvet would have a silk casing. This, however, would price silk duvets out of the market. A quality silk casing outside a silk filled duvet would in reality make silk duvets prohibitively expensive. However, there are silk duvets available that do have silk casings and compare favorably in price with cotton covered duvets. This at face value looks almost too good to be true, and sadly it usually is.
See, it is possible that you can get an inexpensive silk comforter sets for beds with silk casing, as long as you know how to identify real silk.