Copper has a low enough melting point that I’m able to just hit it with an oxygen-acetylene torch and turn the pennies into a solid little blob. Then I hammer that down to a somewhat regular size and shape that’ll fit in my rolling mill.
On this particular ring I ran either side through the mill while leaving a bulbous lump in the center. I was originally planning to set a moderately larger oval ruby in it, so I needed as much metal for the head as possible.
From there it was just minor shaping, setting the stone, and a long stint on the buff. The slanty body lines and slopes on the top are actually an artifact of the rolling mill step. The mill is older then me, and likes to consistently cockeye your stock to the left. But consistent angles make for pretty geometry!
I had just enough metal to cover the height of the ruby, but I didn’t account for the curved surface of the ring. Once I sanded down a flat on the top for the stone to go in, it was ~2mm shorter than the stone.
You could just set a stone like that anyways, I have a few vintage pieces with oversized stones in undersized mountings. The culet, or point of the stone, pokes into your finger just a little bit. Makes em a real bitch to work on though, as you’ll need a slotted mandrel and a careful touch to do practically anything.