Pure copper ball chain 4.3mm available in various lengths.
Please continue to research the health benefits of copper. Copper will oxidize in the presence of air. Think of the Statue of Liberty which is pure copper and green.
We recommend purchasing one of our polishing cloths to remove the tarnish or wipe your chain with ketchup, rinse and polish with a clean microfiber cloth. You can also use a solution of ketchup, vinegar, lemon juice, and dish detergent to soak your copper, rinse and buff with a clean microfiber cloth.