Silver ring...almost a heart stopper

Went to an old school yard yesterday and found this sterling ring. Let me tell you about this place. They must have heated this school with coal back in the day and dumped the ashes in the school yard. The area in which I found the ring was a constant buzz of signals. Probably didn't help that I had my disc set on 1, but anyways in this sea of signals I heard a high tone and the F70 locked on the target. Signal was a slightly jumpy 80. I'm thinking bottlecap (rusty) and even did the wiggle and pull back (some call it rimming). Had a drop from one direction, but not from the other so I figured "what the heck, I'm not hitting anything in this mess of clinkers, might as well dig." Boy, what a surprise I had when I saw silver! And then the "diamond"! Actually once I looked closely at the ring and saw "sterling" imprinted on the inside, I was pretty much positive that the stone was NOT a real diamond. I thought at first that maybe the ring was platinum hence the real diamond. Anyways I was real happy just to be able to discern the signal in that situation with all the clinkers spread everywhere. Also found the Rio Grande Zoo medallion about a foot away from the ring. The only other notable find was the Harley pin. The other pic is of the clinkers and a penny shown for scale.