Setting Round Stones in 4 Prong Settings
Prong setting a gemstone is the most common method of setting. With 4 prongs being the most common of all. There are many ways to set a round stone in a simple 4 prong setting, I am going to show you the most common using simple bench tools. In this example I will be setting diamond simulants in a silver ring.
Let's start by taking a look at the tools I'll be using. Starting front and center is the ring vice, moving clockwise is a pair of setting pliers, then 3 different types of burs, cup burs, standard setting burs, and 45 degree burs. Next we see a small hand graver, followed by an assortment of polishing wheels for different areas and polishing compounds. At the very top of the picture is a Foredoom hand piece used with the setting burs and polishing wheels. On the far right are a few pairs of pliers, small chain nose and a pair of parallel jaw pliers. Which brings us back around front and a small pile of files. Again, there are many ways to set stones, and just as many different tools, if your jeweler uses a different technique, this does not make him, or us, wrong, it's just a different technique.
The first step with any setting is to polish everything. If you don't start with a good clean prong, there is no way you will ever get it polished once the stone is set, especially the areas under the stone. For this example I'm just using a generic silver ring we made for a customer. I left the casting rough to show how much work may need to be done just to prepare a ring to be set. The first picture shows a rough prong from a silver casting. You can see the mold lines and defects that need to be addressed before any stone can be set. First we use the files to knock down the worst of the lines and defects. Starting with a rough file and then working through several files, each one more fine than the previous one, until we get to a smooth, but rough, prong.
Next we polish the setting. Starting with a rough compound we can work out the scratch lines left by the files. Then, just like the files, we progress through several polishing steps, each with a less abrasive compound than the one before until we achieve a final finish on the prong, the baskets, and the inside of the head. Of all of these, the inside of the head is the most important area to get perfect since once the stone is set there will be no way to go back in and fix any scratches that may still exist.
Now that everything is polished and ready to set we need to re-verify that the stone will fit this mounting. During the polishing process it is possible to move the prongs and we need to make sure everything is aligned properly before we start cutting. To cut the seat for the stone we need to find a setting bur that is the same size or slightly larger than the stone we are setting, in this case the stone is 8mm so I chose an 8mm setting bur. Then I put the bur into my Foredoom and begin to cut the seats. You can see here that I managed to go in off center. With a smaller bur this can be easily corrected, but since I picked a bur exactly the same size as the stone, and we were very close to maximum size on the stone in this setting, it means that I may have over cut the prong on that side. It's a side effect of holding the camera, the setting bur, and trying to get a decent picture instead of paying attention to what I'm doing and why we are doing these demos in silver instead of customer work.
After the seats are cut you can see that all that hard work to polish everything have been abused. There is a lot of flashing left from the cutting process, and scratches in the cut parts of the prongs that need to be cleaned up before we can put the stone in and set it. First I go through with a very sharp hand graver and remove all of the extra metal left by the setting bur. Here is a great opportunity to see the inside of an emergency room if you are not careful with the graver. Next we set the stone into the seat and make sure it's level and ready to have the prongs bent over. The most dangerous part of setting for the stone happens here. If the prongs are not cut enough, if the seat is not level, if there is a bur under the pavilion, or any one of a hundred other variables is wrong, it becomes very easy to crack the stone. Now that we are ready, we take a deep breath and slowly begin bending the prongs over a little at a time moving across the stone in small increments. Smashing down one prong all the way without having the others to support will move the stone and leave you with an uneven setting at best or a broken stone at worst.
Now the stone is set and ready for final shaping and polishing. You can see that once again we've left a lot of marks on the prongs with the setting pliers that need to be cleaned up, and we need to make sure that the prongs all look the same when looking at the ring. Using a fine tooth file we go back in again and smooth out the metal on the prongs and then follow that up with another round of polishing.
And here is the finished product. I look forward to providing more of these types of articles. If you have a specific task you would like to see, or questions about this one, please use our contact form and I will be happy to provide it for you.