This is a wonderful 10 K long chain with Opal slide. It is 48" long with 3 mm wide chain that weighs 9.1 grams. This chain is versatile as it can be worn as a single double or triple chain. It has a dog end for a pendant or fob that has a maker's mark. I do not see a fineness mark so it has been acid tested and tested with a magnet to assure its 10K.