There is no specific color associated with a 100th wedding anniversary. The gift associated with the 100th wedding anniversary is a 10-carat diamond. Those wishing to decorate in a specific color can use the color of diamonds as a reference.
The traditional and modern gifts for wedding anniversaries were put together by librarians at the Chicago Public Library. This includes and expanded list that was created in 1937 by the American National Retail Jeweler Association. While no colors are specified for any of the years, hosts can base a color scheme on the gifts. For example, a 40th anniversary party can use the color red, for the gift of rubies.