Jolin,
Just some thoughts and ramblings.
NN does have a point as far as the ring being/ not being used for wax seal impressions. Although the opposite may be true in that the ring would leave a raised design, overall, with the figures impressed into it, like a framed picture. I highly doubt the ring ever had glass in it as glass was exceedingly rare in antiquity and shows no signs of having any way to mount it on the ring. ( you can't just pour molten glass into the metal of the ring , like a jell-o mold, it would crack immediately from thermal shock ). To me the ring design definitely looks "functional" i.e. it was 'used" for something that's why my bet is that it was a wax impression tool and not simply a jewelry accessory. Also, as we speculated before, the styling definitely looks as if it could be medieval. ( very, very old ) The part I would be concerned about is Neil's final point that the ring would probably definitely be classified as "treasure" and as such may be subject to official "claims". Being that you found it in Germany, you may be safe but be careful who you tell what to or you may have someone knocking at your door telling you to hand it over. Don't get me wrong, I'm a proponent of saving and preserving history but entities ( like the British govt.with their infamous tax and antiquity laws ) would love to get their greedy little hands on it and give you (the true owner now ) a percentage. ( You may recall we had a Revolutionary War some time back over the British government's policies towards taxes etc, it was in all the history books ).
The ring is yours now, you earned it. If the "Royal Dept. of Give Us Your Money & Valuables" or any other panhandling official entity does contact you, tell them to get their own detector and go out and EARN it. I got your back.
HH
Scott