Down can vary in color, from white to dark gray depending on the age of the bird and the season in which the down was harvested. The color of down does not affect its ability to insulate - in other words, a dark gray down will insulate just as well as a white down of the same size cluster and maturity.
Aesthetically speaking, white down is generally more preferable to gray down since a gray down can show through a fine white down proof ticking, making the comforter appear "dingy". White goose is more expensive then gray down. Like duck down, we are seeing more gray down being used as a way to keep costs down.
