Antique green ring

Beautiful, quite clear and pretty; bright kelly green color (i was surprised to see viewing on iPhone makes color look quite different than on tablet, my tablet dulled the color); prong set, faceted stone (is it lab made emerald, quartz or glass?) in an exciting antique setting. Dramatic pair of dragons flank the crown reaching down to the band. Marked with a U with an arrow struck through it; I do think it’s quite old. Vintage condition. Selling as I simply don’t reach for it anymore (too much time in the garden very little time eating bonbons).