9K would be harder the lower the K the more metals are mixed with the Gold. 24K is considered pure gold. 24 K Gold is more malleable which means soft and easy to change form. High School Rings are usually 10K Gold. Wedding Bands are from 10-14K Gold in today's market. The intrinsic value of Gold is so high that jewelry is very expensive right now. So rings are thinner and not as high of a K of Gold. Check Kay Jewelers on the web.