These earrings are made using a Japanese technique called Mokume Gane (which means woodgrain metal) which is achieved through a process of layering different metals to create a sheet that can then be patterned by removing some of the top layers. These were made with copper and sterling silver and have between 16-32 layers of metal. The backs of the earrings are silver, as are the posts, so no need to worry about copper on your skin! // Due to the nature of this technique, no pair will be the same, and the earrings within each pair will be delightfully different. You will receive one of the pairs pictured.