HI there,

I do forge Copper regularly, I do forge damascus regularly, I did forge Cumai and Mokume blades enough too and I stopped doing it.

I never heard of anything bad happening between carbon steel and copper or copper alloys as long as the weld is well done. However I never forged Cumai/Carbon damascus for a ring (welds might suffer if you twist or create more tension in bar?),... but I suspect on another note that a mokume of Copper, Nickel or Silver and potentially Gold will look awesome per se.

When in contact with skin acidity or atmosphere itself, Copper/copper alloys will oxide and can easily being watched with soapy water afterward.

However if the weld is not done properly the worse that can happen would be an increased oxidation of the transition area with the carbon layer overtime - creating delamination. This should be taken into consideration in the case of your heirloom making question potentially.

Moreover I believe that copper oxide is recognized in a few US states as a "poison" when in relation with food utensils.

Your question can be also orientated toward a stainless damascus with copper inclusion such as Takefu steel with their Yu Shuku.

This is maybe more the road that you might want to follow for a long time heirloom piece that you can wear everyday. I heard that Damasteel was selling such Jeweler stainless damascus, without copper though...

Those comments are just food for thoughts.

Good luck,

Francois

Francois Mazieres Brilliant answer, thank you.