Despite how it's advertised, most silver is not actually pure silver. Instead, it's made up of 99.9% silver and certain additional materials, such as copper. This is because silver is a softer metal. When not mixed with other metals, it's more susceptible to damage.
925 silver uses additional metals to achieve stability. As its name suggests, it's made of 92.5% silver. The additional 7.5% consists of harder alloys such as copper. Sterling silver is just another name for 925 silver. Celtic Crystal Designs uses copper as an additional alloy. No nickle is used in our quality sterling silver jewelry.