In its pure state, silver was considered too soft to retain a crafted shape or design, so it was alloyed with other metals for increased strength. Today, silver is most frequently alloyed with copper. The best known alloys are Sterling (92.5% silver) and Britannia (95.8% silver). Another standard for jewelry is 80% silver. Pure or alloyed, silver tends to tarnish. The dark yellow or black patina can easily be removed with commercial cleaners or silver polishes.