Re-tipping on larger diamonds
The 18-karat yellow gold ring in the photos above with its one-carat centre diamond recently came into the shop for re-tipping. This piece is approximately 10 years old and is right on schedule for re-tipping. The corners of the chevron prongs are worn away and the stone’s edges are poking through. On a job like this one, one might be very tempted to use a laser to build up the prongs; it certainly would be faster. However, I think doing so would be a big mistake. The potential for damaging this stone with a laser is too great. I prefer to use the conventional torch re-tipping methods.
To re-tip over chevron prongs, I’ll need to create tips out of gold stock. For this particular job, I started with a 6-mm length of square stock and filed it into a long chevron-shaped prong. The stock was then cross-sawn into four equal lengths to make the new prongs. There should be no shortcuts to a job like this. This repair is difficult and time-consuming. It’s understandable why bench jewellers would be tempted to take the easy road out and use a laser welder. However, the risk of damaging this expensive stone is too great. As bench jewellers, we should want to do the job correctly, as this is the reason we chose this profession. Personally, I find it very satisfying to do a job well.
I have to confess I broke my own rule about not using a laser on a job like this one, but like all rules, there’s an exception. I used the laser welder to tack the new prong tips in place and was careful to do so in an area where there was no chance of hitting the diamond, even if the laser beam were to ricochet, as it is often apt to do.
This ring contains 16 invisible-set princess-cut stones. Working with invisible settings can be problematic, so solder choice might be an issue. As this ring has never been repaired, I chose 18-karat hard plumb solder because of its resistance to pitting. An argument can easily be made to drop down to a medium or easy-flow solder to avoid undo risk of something shifting in the invisible sets. Questions like this are personal calls made by the jeweller on a case-by-case basis. Please remember that boric acid solution only protects diamonds from heat for a short time. For this job, I soldered two prongs, cleaned the ring in pickle and sonic, and reapplied the boric acid before continuing.
For me, finish work is a bench jeweller’s signature. Unfortunately, it’s another area where jewellers often take shortcuts. Personally, I consider this the best part of my job! I have a separate set of gravers used just for working around stones. These gravers are neither sharpened as finely as my engraving gravers nor are they polished. The photo to the left illustrates me using a flat graver to detail out one of the corner chevron prongs. After finishing all four prongs, they required only a light touch of the buffing wheel.
Re-tipping is another area where bench jewellers need to price out jobs separately. This one took one hour and 15 minutes to re-tip four chevrons prongs. In addition, these prongs are thicker than regular ones, so material costs are higher. Further, this ring is 18-karat gold, not 14-karat. I priced this job at $45 per prong.