It better to keep away from base-metal alloys entirely, and instead use pure precious metal on our wedding ring enhancer.
All nickel free list:
Sterling silver is an alloy, but there is 0% nickel, so most people use it. At least sterling silver use 92.5% pure silver and 7.5% copper. One more kind of sterling silver, Tarnish-resistant Argentium™ sterling silver is 6.3% copper, 1.2% germanium, and 92.5% silver.
Niobium is a metal that never attracted to any other metals, so it’s very safe. Absolutely nickel free in nature and very low corrosion. Niobium available in anodized (non-plated) colors.
Read more.