Repair Techniques


Ring Sizing


There are two ways to size a platinum ring using a torch. One is using the soldering technique, the other using the welding technique. Let’s begin with the soldering technique.

I do not recommend using lower temperature, traditional solders for sizing rings. These lower temperature solders contain no platinum, but are a mixture of palladium and silver. The filler solder is softer and will polish out of the seam leaving a visible indentation. It may also oxidize leaving a dark line in the sizing area. Plumb solders polish flat and do not turn dark. Usually the welding technique is preferred over soldering, as it is makes a seamless connection, which solder does not.

To make a ring one size smaller, remove 2.52 mm of the shank.  Scribe the distance onto the shank and remove the metal with a jeweler’s saw. Gently bend the shank together closing the gap. Cut through the seam one more time; this aligns both sides and guarantees a tight seam.

Roll a small piece of platinum hard solder until it is about .25mm thick. If a rolling mill is not available, just hammer a small piece flat using a bench block. Wedge that small thin piece into the cut allowing the tension of the shank to hold it in place. The solder piece should not be larger then the cross section of the ring so that no solder spills on top of the ring during the operation. Grab the ring away from the seam with the Third Hand and solder the shank (use appropriate eye protection). You are finished as soon as the solder has flown. At this point examine the seam to see that it is filled all the way around. You may have to re-solder if it is not. This creates a complete metallurgical bond.

Once the ring has been soldered, round it gently on a mandrel using a mallet. There should be as little damage to the shank as possible. A mallet will prevent hammer marks on the ring. As no solder pilled over, there is really no need to use a file. A file will make deep marks on the ring. As no solder pilled over, there is really no need to use a file. A file will make deep marks that will only be removed. Instead, use a polished burnisher and rub over the seam, making it invisible. Sleight very fine sanding and polishing will finishing the sizing.

To enlarge a ring size, repeat the above technique, except add 2.52 mm of sizing stock. Again, a tight fit is needed; I prefer to solder the piece in place in two operations. Sizing a ring up or down a size is actually easier with platinum, as heat does not travel as quickly as it does with gold. A word of caution here. It is not possible to solder or weld close to stones, using hard and high temperature solders. You will end up burning diamonds and other stones. Be sure when holding the ring in place you use tungsten tweezers. Steel tweezers may leave a dark spot on the ring and when heat this ring again, this dark spot will become a permanent contamination unless removed.

Sizing with the welding technique is a straight forward operation. Once the shank has been cut, it is not necessary to close it without a gap or cut through again. A small gap or groove filed around the cut is beneficial. Sometimes, when a ring shank is thick, the molten platinum will not fill the gap all the way through, leaving an incomplete junction.  Once rounded and filed down, the ring can break at the seam. This is why a chamfer filed around the seam creating a small grove between the ends will eliminate this concern. It will fill the seam with molten platinum during welding and thus eliminate any space. I usually hammer the piece removed for a down sizing flat and use it as fuel. This technique makes sure that the alloys match. The piece should be about 1.5 mm larger than the cross section of the ring. Wedge the small piece of the same platinum alloy the ring is made of into the cut. Using a sharp oxidizing flame melt the piece into the gap following it all the way around the seam. This creates a seamless bond. After welding, file the excess platinum from the inside of the shank so that it can be rounded on a mandrel. It is also good practice to make the ring slightly smaller than needed. Hammering it to round it will stretch it to the desired size and work-harden the shank for easier finishing.


This is part two of the series Basic Platinum Repair Techniques written by Jurgen J. Maerz, Director of Technical Education for the Platinum Guild International USA