Our copper ring cores are easy to use. They can be used as a stand alone ring, engraved, embellished with stamps or punches, or for lovers of metal clay, these ring cores can be co-fired with silver, bronze and copper metal clays. These ring cores come in half and whole sizes 4 - 11.5.The ring size will stay consistent during firing. The finished interior is a bonus. Check out our TechSpecs below to read about our test results.