1. A duvet must never be sewn straight through, as this lets warmth escape. The duvet will be cold as it is nothing but thin spots. It must have inside fabric baffles to provide an even layer of down.

2. Baffles must be deep enough to allow the down to loft up fully. Often duvets are made with narrow baffles to make the duvet appear puffier due to thicker and thinner spots.

The boxed baffle design shown at the right is the only appropriate baffle design.

3. A duvet must be chambered, or the down will gradually drift into the corners, leaving the centre empty and cold.

4. The chambers must be sealed off from each other. Many box duvets are made with gaps in the walls, as shown in the "X-Ray" diagram. You can't tell by looking at it, because the stitching itself is continuous, but the baffles have gaps. In the course of 2 or 3 years, most of the down will drift to the ends of the duvet.

The Sealed Baffle Box Design
After experimenting with many different styles over the years, St. Geneve found that the best is this design that originated in Europe. There is no shifting of the down, and it can loft up completely due to the extra deep baffles. There is a fabric "valve" between each chamber that is opened by the filling tube when down is being blown in. When the tube is removed, the valve closes permanently, so that each chamber is individually sealed to prevent any shifting of the down filling. This is guaranteed for the life of the duvet. St. Geneve sew the pattern of boxes so that they are not square, but rather a rectangle. This makes it very simple to determine which is the top and which are the sides of the duvet when changing the duvet cover and making the bed.