Stainless steel domed Omega necklace is maintenance free! It elegantly sets off many pendants and is gorgeous all by itself. All with no polishing or tarnishing! Available in 4mm or 6mm.
 
If you're not sure which thickness to get, consider what slides you'll be using on them. Not every "bail" (the part that holds a chain) is large enough to go over the 6mm Omega, but the 4mm will accommodate most pendants.