Vintage Opal Ring SZ 6.75 in 10K Gold w Scalloped Frame & Unusual Hallmark, 2.5g

Oval-shaped precious white opal (8mm x 6mm x 2mm), approx. 1/2 carat, prong set in a 10 karat gold ring. The frame has interesting “teeth” — six on top and six on the bottom. Like a buttercup ring that’s gone feral! Stamped “10K.” There’s also a distinctive maker’s mark — what looks like a butter churner! — but I don’t know to whom it belongs. Based on the design and the marks, I think this ring is pretty old (pre-1930?) so I don’t think the opal is original to the ring because it’s in pretty good shape. The face of the ring is 13mm (1/2″) tall and 10mm (3/8″) wide. The band is 1.8mm wide and 1mm thick at the center back. Size: 6-3/4; can be resized. Weight: 2.5 grams