This is a roman coin, I'm not sure of the date and who is on the front.
3Hi, welcome to History.SE. Could you give us measurements and, if possible, show us the back face? Straight on, well lit, high resolution images will help as well.– SchwernSep 26, 2018 at 16:58
5The lighting and focus kind of make it look like a stock photo or some sort of product. Did you find the image somewhere or did you take the photo yourself? Either way, do you have more images or any other information about it?– GiterSep 26, 2018 at 17:16
This coin appears to be showing Constantine I, timeframe 307-337 A.D. Numerous similar coins can be seen on this search, mainly at commercial sites.
A good look from a site here
The above site lists this coin as:
DIVUS CONSTANTINE I THE GREAT (Died 337). Ae. Antioch. Struck under Constantius II and Constans.
Another good image can be seen here
as a side note: whoever made the ring did cut the whole "left" side of the coin's inscription to conform to the smaller diameter– TrishOct 4, 2018 at 15:32