The groom’s I had to redo because the size I was given was wrong. It looks huge here, but the final piece was only a half size bigger than hers.
It was my first real experience casting anything other than ingots. I ran some tests to determine the best way to do it using the equipment I had available to me.
Initially I tried to cast them in slate. Slate has a low quartz content so it can stand the heat of molten metal without cracking. It’s also soft enough that you can carve in it.
I created a jig in which to attach my rotary tool and cut out the ring shape. But it wasn’t very steady. I managed to get a few molds made, but the test casts weren’t terribly successful. I might be able to do better if I tried it again. But I haven’t had reason to just yet.
Next, I tried cuttle bone casting. This is where you make a mold out of an actual cuttle fish bone. The kind you give to birds to chew on.
I made a ring out of brass, pressed that between two slabs of cuttle bone which compacted around the model, creating a cavity the shape I wanted.
This works beautifully for silver. I made some awesome test pieces.
However, silver is much more conductive than gold and cools much more quickly.
When I tried it with the gold it stayed molten longer which allowed it to burn the mold out of shape and flow into the newly created space.
It might be possible to do, but too expensive to experiment with right then.
In the end, I bought a sand casting kit. Again I used the brass model I made for the cuttle bone. It was a little dodgy for such geometric shapes. It did the trick but I think I removed about a gram worth of dust to smooth them out.