Down is defined as fine, soft, fluffy feathers forming the first plumage of a young bird and underlying the contour feathers in certain adult birds. The shape of a down unit or cluster gives it loft and traps the air to keep you warm. Down can be one dimensional; flat with quills, two dimensional, or rounded, three dimensional or representing the shape of a dandelion seed pod.
Down comes in two types, Duck and Goose. As far as the warmth factor go duck and goose are equal. The difference lies in the fact that duck down clusters take up a smaller area. In order to make a full comforter, manufacturers compensate by offering higher fill ounces for duck down.
Down is actually measured in the U.S. using a method known as fill power. Basically this translates into the amount of fluff the down has. The higher the fill power number the better the quality of the down fill. A fill power of 600 is considered good quality, 700-800 is considered excellent quality and anything over 800 is considered superb quality.
The weight of the down blanket also makes a big difference in the warmth. When you are looking for a down comforter it is important that you know what you...