In an ideal world every silk duvet would have a silk casing. This however would price silk duvets out of the market. A quality silk casing on a silk duvet would in reality make silk duvets prohibitively expensive. There are silk duvets available that do have silk casings and compare favourably in price with cotton covered duvets. This at face value looks almost too good to be true, and sadly it usually is. Before you purchase a silk duvet with a silk casing you should ask what the momme of the silk casing is. Momme is the unit used to grade the quality of silk. Pfor a detailed explanation of this. A silk casing should have at leaset a momme rating of 19. Anything lower and you could encounter durability issues and herein lies the issue. What would initially seem a great price for a silk cased duvet could soon turn into something worthless with a hole in it. We are not saying don’t buy silk cased silk duvets, but just be sure you know what you are getting before you make a purchase.