I had a hard time cleaning the dirt/stain off the ring, and it must of been in the ground a long time. My first thought was copper or brass, but I think it would of rang up higher on the CO. Wouldn't real gold cleanup nicely?
In most cases, gold comes out of the ground looking like new. I have seen gold rings come out looking bad because of heavy use of fertilizers, causing the other alloys mixed in to turn brown. I think Uncas is known for costume jewelry as well. The '8' stamped next to their mark is most likely a size (not typical on fine jewelry), which could indicate that it was a ring sold on a display card or something where you just picked a size, so it might be some other metal such as brass.