Several months ago I was asked by a jeweler if I would write an article that would show the process of a basic jewelry repair. This jeweler wanted to be able to show his customers the process from start to finish. He said that he would laminate the article and set it out for customers to look at. This project will be to size a wedding set smaller, remove an existing diamond and crown, solder a larger crown and set a 1.70 ct. diamond. The rings I will be working on, the new crown and the 1.70 ct. diamond are shown in photo1.
The first step is to clean the rings so there is no oil or dirt behind the diamonds. Oil and dirt can bake onto the surface of the diamonds during soldering steps that could cause the diamonds to darken, and in some cases the diamonds must be removed from the jewelry piece, be cleaned mechanically, and then reset. After cleaning the engagement set I size the rings. I choose to size the rings before setting the large diamond so any loose diamond melee can be tightened without fear of damaging the larger diamond. To size the rings smaller, measure the amount of metal to be removed at the bottom of the shank. These rings need 3/4 size removed from each. After scribing the shank with dividers, saw the piece from the shank, or use a sizing shear as seen in photo2.
My sizing shear has seven cutters from one half size up to two sizes, in quarter size increments. This is a handy tool that speeds up the process and leaves a clean parallel cut at the sizing point. I then bend the ring to close the gap at the bottom of the shank. I either gently tap the ring on the sides with a rawhide mallet, or as in photo 3,
close the gap with a bow closing pliers. The bow closing plier was designed for installing the bow (or loop) on the top of pocket watches, but it works great for ring work also. When the ring shank halves come together, make sure they are parallel with no gap to ensure a strong solder joint. I then solder the joint with hard solder the same karat and color as the shank itself as seen in photo 4.
The rings are then soaked in an acid bath to remove flux and oxidation caused from soldering. I then file any excess solder from the shank and sand the shank smooth. Often I will file a small bevel on the inside corner of the shank as shown in photo 5 to remove the very sharp corner that may cause discomfort to the wearer.
There are several ways to remove an existing crown. If possible I like to heat the ring until the solder melts and pull the crown off as seen in photo 6.
However, this is not always possible. An example would be if the crown had been laser or arc welded in place before soldering. In this case the crown would have to be cut off and the ring must be drilled to accept the new crown. After the old crown is removed I modify the ring to fit the new crown by enlarging the peg hole to fit the new crown peg and smooth the crown pad to remove any old solder. After the crown is fit to the ring it is placed in a clamp and soldered as in photo 7.
The inside of the ring is smoothed with a file and then I use a rubber wheel impregnated with ceramic particles to remove the file marks before polishing. This step saves much time at the polishing station.
My next step is to set the 1.70 ct. diamond in the crown. Upon inspection of the stone I notice inclusions in the stone running from one side of the stone to the other. I place the prongs in a position to lessen the chances of damage to the stone during the setting process. I then cut the seat for the stone with a ninety degree heart bur and cut a bearing seat in the under bezel of the crown as seen in photo 9.
I then pull the prongs back just enough to slip the stone in place and check the fit. Now in photo10, I very carefully pull the prongs up to the diamond without putting undue stress on the stone.
With the prongs in place and pulled up to the stone, the stone is still loose. Instead of putting downward pressure on the prongs to tighten the stone I squeeze one set of prongs together with a plier, first one set as in photo 11, I then turn the ring 180 degrees and squeeze the other set of prongs together.
Now I turn the ring ninety degrees and squeeze two prongs together, which is one prong from each of the previous sets, and then the other set. This type of setting is safer because the pressure is inward and not downward over the thin girdle area of the stone. The rings are then polished, cleaned in an ultrasonic cleaner and then steam cleaned. Because this ring has a yellow gold ring body I mask the yellow gold with red laquer so I can rhodium plate the crown without plating the yellow gold areas as seen in photo 12.
Photo 13 pictures the completed engagement and wedding rings.
I have been asked by several young jewelers to show some basic repairs that they could learn and perform in their store. Today I will show how I retip prongs on a pear shaped stone ring.
Notice in photo 1 that the V end and round prongs are worn down to the top edge of the girdle. This stone was ready to fall out of the ring when I received it.
The first step is to clean the article to be retipped or repronged to ensure there is no dirt behind the stones or around the prongs. If there is dirt behind the stones while soldering, the dirt can bake on the stone and can be a real problem to clean. Sometimes the baked on dirt can be cleaned from the stones with acid, but I have run into instances where I have had to remove the stones from the mounting, physically scrape and clean the stones and then reset them. So make sure to clean the jewelry piece very well before you attempt to do torch work, you will save yourself a lot of time and grief.
The next step is to identify the stones that are to be worked on or around. Heat sensitive stones will have to be removed and reset if torch work will be done next to them. Sometimes I will use heat shield or a similar product to protect heat sensitive stones while soldering in their area. Diamond, ruby and sapphire will take heat from soldering but care should be taken not to over heat the stone. Just because a stone will take heat does not mean you can not burn it. Use only gold solder to retip on diamond, ruby and sapphire. Use white gold solder to solder on platinum prong tips if you are not going to remove the stones, otherwise remove all stones and reset them if you are to use platinum solder. Another option is to send the platinum piece to an experienced laser welder. I once knew an inexperienced jeweler that had tried to retip a platinum diamond ring with platinum solder and had burned a couple carats of diamonds in that ring. All the large diamonds had to be repolished and every melee had to be replaced. Another caution is to check for fracture filled diamonds. Fracture filled diamonds have leaded glass filling the fractures to enhance the clarity. If heated, the glass will melt out of the fractures and the stone will need to be sent to a lab to have the fractures refilled. Loupe diamonds carefully and check for a purple or pinkish flash in the stone as you turn the stone under a light. Sometimes you might notice a rainbow flash in the stone if it is filled.
Now with those two important steps out of the way we can start the actual retipping job. Worn prongs are usually rounded slightly. To make a good solder joint, file the surface of the worn prong to a flat surface. This will have less chance of pits in the solder and will make the strongest joint. To prevent chipping the stone it is best to run the file with the girdle of the stone or from the crown facets past the girdle, not up from the girdle.
When rebuilding a “V”end I like to solder two short pieces onto the prong to form the “V”.
Photo 3 shows a piece of gold stock being held by hand and soldered into place. It may be a little tricky to solder the second piece into place without the first piece shifting. One way to combat that problem is to solder the first piece with medium flow solder and the second piece with easy flow solder.
This year at the “Midwest Jewelry Expo” in Madison, I purchased a Tack II welder in the used tool room (Photo 4).This welder has saved a lot of time with different jobs in the shop.
The fixtures I use for this tack welder is a brass tweezer and a ring clamp with a brass contact at the clamping end.(Photo 5). Both tools are wired to the Tack II unit.
In photo 6 I have the ring in the clamp and am holding the first half of the V end in place with the tweezer. I then step on the switch for the tack welder and the part is tacked in place.
If the part is not in the correct position, just snap it off and retack it into the correct position. After soldering this piece place (Photo 8) the excess is trimmed away and the angle of the seam is adjusted to run over the top of the point of the stone.
Trim the end or angle of the second half to match the first half and tack and solder it into place (Photo 9). When the parts are tacked in place they do not shift or move during soldering. What a time saver!
Now with the V end trimmed and filed to shape, I rebuild the round prongs much like I did the V prong but with just one small tip tacked to the prong top (Photo 10).
After soldering, file the tip to the correct shape and if needed touch up the top of the prong with a cup bur (Photo 11).
Photo 12 shows the finished retipping job.
Every so often I receive a pocket watch case to repair a lid hinge. Not to long ago a pocket watch case came into my shop for a lid hinge repair and I thought it would be a good subject for my Shop Talk article. As I was preparing the photos of this watch, it crossed my mind to change the “Shop Talk” title this month to “Tic Talk”, because of the watch, but thought that to be a bit too corny.
When working on antique pocket watch cases, you must always remove any steel parts and springs from the case so as not to anneal the springs or contaminate your pickle solution.
In photo 1, we have the watch case with the lid spring removed. You will notice that the hinge tubes on the case body are still good, so I will need to rebuild only the lid tube. For this project I used 1.5 millimeter heavy walled 14K yellow tubing. Using a millimeter gauge and a divider, I measure the hinge gap on the case body and scribe a mark on the tube for the correct length (Photo 2).
Use an 8/0 saw blade to cut the tubing. A fine blade has many more teeth per inch than a coarser blade, which can prevent a tooth from catching on the tube and breaking the saw blade. When cutting the tube, make sure to cut on the outside of the scribe line and then file down to that line, otherwise the tubing will be too short to match the hinge gap.
It is very important to file the ends of the tube to a 90° angle. A hardened joint cutting jig works well for this job. Simply clamp the tube into the jaws of the jig and file the tube to the scribe line and you have a nice square tube end. My frugality prevents me from spending the money for this tool so I use a tube holder and carefully file the ends square up to the scribe marks as seen in photo 3.
Using a scribe or sharp knife, scribe 2 deep lines at the ends of the old hinge tube to be used as tube placement lines later (Photo 4).
The next step is to remove the remainder of the old hinge tube. I use a small cylinder bur and a round file and remove only the tube material, taking care not to file into the lid hinge groove.
Photo 5 shows the hinge tube being test fitted into the existing hinge. The hinge tube should slide smoothly into place with the slightest resistance, I then place the tube on the soldering block and lay the lid on top of the tube. The hinge tube ends must line up perfectly to the hinge base scribe lines that were marked earlier.
With the lid and tube in the aligned position, heat the hinge area with a torch making sure not to put the flame directly on the tube. Fan the flame back and forth above the tube and apply chips of 14K easy flow solder (Photo 6).
When the solder flows the complete length of the tube, flip the lid over and heat the hinge base (Photo 7) until the solder flows completely to the inside of the lid. It is very important to heat at the hinge base and not directly on the tube. The heat will transfer from the hinge base to the tube. This technique produces a very nice solder joint. It is very frustrating to spend your time fitting a tube only to melt it into a ball. After soldering, let the lid air cool and then pickle the lid in a sparex solution for a few minutes to removed the flux and any fire scale that may have developed during the soldering process.
I then attach the lid to the case body with a new hinge pin made of 14K or brass. The pocket watch case used for this article is gold filled quality, so I used a brass hinge pin. A proper fit for a hinge pin should be snug. To install a snug hinge pin, I round one end of the hinge pin wire to facilitate wire passage past each hinge joint. I then chuck the hinge wire into my flex shaft hand piece, lubricate the wire with beeswax or bur lube and push the wire through the hinge while spinning it with my flexshaft or drill. File and rubber wheel the hinge pin flush with the hinge tube ends and polish.
I prefer to polish the inside of the lid with a small soft brush charged with fabuluster, and the outside of the lid and case with a buffing wheel on the polishing lathe. Buff lightly....just enough to brighten the case to prevent excessive wear on engraving and to prevent removing too much gold from a gold filled case.