Pure silver, also called fine silver, is relatively soft, very malleable, and easily damaged so it is commonly combined with other metals to produce a more durable product. The most popular of these alloys is sterling silver, which consists of 92.5 percent silver and 7.5 percent copper. Although any metal can make up the 7.5 percent non-silver portion of sterling, centuries of experimentation have shown copper to be its best companion, improving the metal's hardness and durability without affecting its beautiful colour. The small amount of copper added to sterling has very little effect on the metal's value. Instead, the price of the silver item is affected by the labour involved in making the item, the skill of the craftsperson, and the intricacy of the design.