Fabricating a Platinum Three Stone Ring
Part III
By Tom Weishaar
1. In my last article I showed how I fabricated the center crown for the marquise diamond of this platinum three-stone ring. In this final installment I’ll fabricate the two outside crowns for the trilliant shaped diamonds.
2. Building a custom platinum crown can be difficult, but I’d like to show you a trick I use to help me get it right. Whenever I build a crown I always start with the upper gallery support. The rest of the crown is built off this support. In this picture I am measuring the trilliant and next to the stones are two strips of metal. The first is platinum and the second is an identical strip of copper wire. I rolled out both pieces of wire at the same time; they each measure 1.25mm by .80mm.
3. I like to use copper wire to fashion a test support before I commit to platinum. The copper acts similarly to platinum and it is cheap. It only takes a few minutes to make a copper faux support, and those few minutes could save me an expensive redo. First, I put a slight curve in the copper wire to match the curvature of the stones. The trilliant diamonds measured 7.40 mm (average) from point to point. From that I deducted about .5 mm so that the support will be smaller than the stone. Then I deducted an additional .8 mm for the thickness of the wire. After these deductions my new measurement is 6.2 mm. I then used a pair of dividers to strike that measurement three times onto my copper wire.
4. Next I use a fine saw blade to cut a diagonal line halfway through the copper wire. By cutting the wire on the diagonal it allows the wire to fold on an angle, making the underside smaller than the top.
5. After the diagonal saw blade cuts are complete I come back with a square file and create a diagonal notch. As the wire is folded I will need to file the notch wider so that it can fold into a triangle. Be careful not to file the notch any wider than necessary or you will end up with a gap that will need to be filled in.
6. When I check my copper sample against the gemstone I make sure that the support is 10% smaller than the stone and that no part of the support is visible from above. The curvature of the support should match the stone’s girdle line. You can see from this picture how the supports slope down and in. This is the result of the diagonal cutting and filling.
7. Once I am happy with the way my copper supports fit the stones then I transfer the same measurements and curvature to the platinum and make the real supports. In this picture the seam and the notches are being soldered closed using 1700 platinum solder.
8. These platinum supports have been lightly filed and sanded to help them match the outline of the stones. I hope you can see the value I place in making the copper sample supports for these triangular shaped stones. I also find them to be helpful with all stone shapes, but especially rectangular shaped stones.
9. In this picture I am checking the size of the trilliant support and how it will fit into my ring. I can still make slight adjustments to the wings on the shank if I need to change the width of the gap.
10. The next task is to create the chevron or V prongs that will hold the trilliants. I always use chevron prongs when setting pointed stones as it holds them better and has a nicer appearance. To slice this 2mm square wire I use a pair of notched pliers. I’ll slice on a diagonal for about 3mm then flip the metal over and cut from the other side. This way my saw blade doesn’t get a chance to wander.
11. The outer chevron prong will extend from the shank and out past the wing support.
12. I’m using a 90 degree bearing bur to cut a notch in the upper tip of the support wing. This will accept the chevron prong.
13. The ring is fixed into my ceramic block and the chevron prong is soldered in place. I’ll use 1600 platinum solder from this point forward as I don’t want to take a chance of the solder flowing in any previous solder joints.
14. I’m using a small ball bur to cut a notch in the chevron prong. The notch will accept the point of the upper gallery support and hold it in place during soldering.
15. The work on this ring is progressing quickly and with just a few more additions and I’ll be ready for setting.
16. In the picture I am shaving the inside corners off my upper gallery supports. I want a nice flat spot on which to solder my prong. I’m using a knife edge bur to remove the corners. These are extremely aggressive burs and I must be very careful as they tend to grab the metal and then cut in unwanted directions.
17. The base of the inside chevron prongs end at the base of the upper gallery support. I could take the prongs all the way down to the ring shank, but I think this tends to make the ring look too “prongy”. There is no right or wrong decision on this topic, just a design consideration.
18. The ring is completed and ready for setting. I do think it is a good idea to final polish fabricated jewelry prior to setting. I would not want to find a pit or an exposed seam that could not be repaired after the stones were set. If you were to send this ring in for judging then a pit would and should knock you out of the competition.
19. After setting, your prongs should all be tight to the stones and free from any tool marks. This ring required 15 hours of labor to complete. I hope these articles have helped answer any questions you might have had about fabricating a three-stone platinum ring.
This article first appeared in Bench Magazine http://www.BenchMagazine.com
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