KVK1 marked 3

[hcliffe]

Is this one okay? Is it made of zinc? Is the blackening where the silver finish has been absorbed into the metal? Would vaseline help reduce this?

[hcliffe]

2

[Frank K]

It's a zink cross, you can tell that eg by the integrated catch and hinge and the bubbling.

It's not mm3 but mm4 imo. The mm on the pin can be hard to read and the rest looks like 4, so that's my guess.

The blackening is a natural thing that happens with zinc over time. What's worse is that it looks like your cross has zinkpest. I'm not a big expert on how to threat that but believe that vaseline can help. Try to do a search here for zincpest.