For our last example, we’ll look at the platinum, three-stone ring in the photos above. Featuring about 1.50 carats in diamonds, this used to be a nice ring. The woman who owns it wears it hard, as evidenced by its deep scratches. The outer prongs prematurely wore down in about eight years. The customer took the ring to a jeweller for repair, and as you can see, the prongs were poorly built up using white gold solder. The haphazard work is apparent even to the untrained eye. No longer trusting her previous jeweller, the woman brought the ring to me. I am sorry to say, but examples like this are very common.
If at all possible, we should avoid using gold solder on platinum jewellery. Gold contaminates platinum and can forever alter the method with which future repair work can be done. If you are inexperienced in working with platinum, you owe it to your customers to suggest a more qualified jeweller. In this particular case, the gold solder did not find its way into the bulk of the ring and I was able to remove the contaminated prongs.
After taking out all three diamonds, I used a Kraus bur to grind away the prongs. I stripped each prong all the way down to its base for several reasons. If I had just soldered a short prong tip on top of the old prong stub, I would have had to use a butt or blunt solder joint. This is the weakest type of joint, and it would have failed in short order. Removing the entire prong allowed me to create a long lap joint, which is the strongest type possible. Additionally, the seam for this lap joint would be nearly hidden behind the new prong, reducing the possibility of a visibly pitted seam.
Prior to adding the four new prongs, all the ring’s surfaces were sanded, polished, and cleaned. This is my only opportunity to get into the tight areas and restore them to perfection. As you can see in the photo above, I used a miniature sanding disc, with both 220- and 1000-grit papers. For more on how to make a sanding disc like this one, see Tom’s Tool Tip.
Before soldering the four new prongs, I put each into a flex shaft and slightly tapered them on a sanding stick. Tapering prongs is purely esthetic. Personally, I prefer the look of prongs that become thicker as they approach the diamond.
I’ve discussed soldering platinum before, but there are a few key points that bear repeating. First and foremost, always wear a number ‘5’ or darker protective eye lens when soldering platinum. The intense heat (in this case 1600 C [2912 F]) creates significant ultraviolet light, which is strong enough to damage your eyes and can lead to cataracts.
To complete the soldering job, I added tiny chips of 1600 platinum solder, which were flowed into place in the channel carved out by the Kraus bur. Next, I cleaned the ring, laid out the prongs, and reflowed the solder to complete the connection. I sometimes use a laser welder to simply tack prongs in place prior to soldering. Prongs should not be laser-welded in place as a shortcut to soldering. The depth of the weld from lasering alone will not be strong enough to permanently secure the prong in place.
The finished job turned out well, and my customer was very happy to have her ring made safe and beautiful again. In estimating a job like this, I allotted two hours for labour. The materials fee when working in platinum is very high. This job required slightly more than one pennyweight of platinum for which I charged a normal triple markup. All told, this job worked out to $130 per prong.
As this article has illustrated, there are many repair methods a bench jeweller can use when approaching a re-tipping job. A great jeweller learns to assess each job individually, and applies the proper method of repair to fit the need.
I hope you enjoyed this article on re-tipping versus reconstructing prongs. In the next issue, we’ll look at repairing bracelet links. Thank you to those who have written me and offered your feedback.
For more see, If you can’t afford to replace it, don’t laser it.
Tom Weishaar is a certified master bench jeweller (CMBJ) and frequent speaker on jewellery repair topics for Jewelers of America (JA). He can be contacted via e-mail at firstname.lastname@example.org.