All our copper chain is solid copper, the jump rings we use are solid copper and the clasps that we put on the items are solid copper.
The most popular type is the lobster claw clasp. It is easy to connect the chain around your neck by pulling the lever up or down.
The sister hook clasp is solid copper, it closes by taking the two claws and rubbing them together when you close it to create a nice snug closure.
The sister hook clasps works real good on bracelets and chains that you want to put on and wear it all the time, it is harder to put it on and close and to open and take it off, used more on thicker bracelets.
The fold over clasp is solid copper and clicks shut.
The durability is better on the lobster claw clasp to put on and take off then the fold over clasp.
The fold over clasp snaps shut and pulls open, it is solid copper.