I made my girlfriend a pendant for Christmas this year. It’s an 8mm Round 2.6ct titanium doped sapphire from Turtle’s Hoard in a sterling silver setting that I designed. Turtles Hoard sells really cool gemstones left over from industrial and scientific processes. In this case, these were grown to be cores for lasers, likely of the high intensity femtosecond variety.
I designed the setting in CAD and 3d printed it in PETG to check the fit on the stone, and then moved on to trying to make it in metal. I’d never cast anything before, but I followed this guide for steam casting (https://www.myheap.com/casting-molding/my-heap-mold-book/chapter-10-steam-casting/steam-casting-lessons.html?showall=1) and it went well.
I printed the model in a wax filament from machinablewax.com. I used SC20 as my investment, degassing it with a vacuum chamber I built for another project. I used an old coil style hot plate with a flower pot on top of it as my burnout oven and burned out the wax for 3 hours before casting. For the first few casts, I used brass to avoid wasting silver. However it was difficult to melt with the propane torch I was using and seemed to produce lots of slag. After a couple tries with brass, I moved on to silver. I had a really tough time finding sterling casting grain locally, so I bought a 1oz fine silver coin and alloyed it with copper instead. The first silver cast came out well so then it was on to cleaning the cast up and polishing.
Setting the stone was by far the most difficult part and I did a pretty poor job to be honest. I ran out of time to order burrs so I just used a diamond tool on my Dremel which was a mistake. It was the wrong shape for the stone and was hard to control. If you look closely, the prongs aren’t pushed down particularly evenly and don’t properly follow the contour of the stone. But the stone isn’t going to fall out and it looks good enough, so I’m more than happy with it for a first attempt.
Overall, this was a super fun project and was honestly much easier than I expected. There are quite a few things I would do differently if I were to do it again, but I’m really happy with the way this turned out.
