Help! Black residue on ring

[moldyCheese]

I recently had someone reset a morganite stone into a 14k gold filled ring. They themselves did the gold-smithing.
It came in one evening and I put it on, and later was down for the night (cooked a little, normal hand washing). The next morning there was what seemed like a dark coating that formed on the inside and also what looked kind of like rust around the sides of the bezel. The dark coating also left a little bit of a mark on my finger that eventually came off.
I did some "web md-ing" and found that it a possibility could be due to "corrosion in the base metal". I brought this up to the jeweler and she didn't have an answer, but is saying she thinks I'm allergic to base metal. However, I'm not sure how my finger could have a reaction that caused my ring to get a dark coating and rusting? I also don't have any issues from jewelry except red rashes to cheap jewelry after extended wear.

I'm hoping someone might have some insight into it and possibly have a solution up your sleeve. I really want to wear it, but I don't want to go through the process of possibly re-doing it but in solid gold.

In the pictures I circled the "rust" and in the other pic the fingers are pointing to the portions of the ring that didn't darken to show the contrast: