Help identify metallic ring

[rotarurazvan07]

Hello everyone
I found this ring while metal detecting near a river, in Romania, at about 5-10 cm depth.
I cleaned it by rinsing with water and a toothbrush. You can see attached photos of before and after.
Im looking to determine the date and origin of this ring, and any information would be helpful
Thank you

 

[VRBeauty]

It’s possible the back of this ring was broken through use or damage, but it looks more like it was originally made with an adjustable split back. This would suggest that this is a mass-produced piece, most likely fairly inexpensive. The green color looks like verdigris, a type of tarnish that can form on copper or brass.

I hope you’ll find many interesting things with your metal detecting!