This is a crystal quartz necklace. It's 70cm long, so you can put it on over your head. My mother had a custom one made at an exhibition because she doesn't like clasps. There is no clasp. It's cut and sparkles beautifully. It seems to be durable with a special double wire. Thickness: Approximately 7mm Please check the photos. I'm not an expert, so I don't know the details. It seems to have been used 1-2 times. Please understand that it has been stored at home. The box is not included.