There's some supposition that copper jewelry is therapeutic, but mainly I just like the metal.  It's soft and easy to work with, and cleans up to a beautiful pinkish-orange.

14 AWG 1/4" ID
Half Persian 3:1, hand-hammered hook clasp

14 AWG 3/16" ID
Jens Pind, hand-wrapped toggle

18 AWG 1/4" and 5/32" ID
Markovian Helix variant (only one edge stitched), hand-wrapped hook

18 AWG 5/32" ID
Turkish Round, hand-wrapped triplicate hook