Professional Jeweler Archive: Solder and Heat Issues for Lab-Created Moissanite

December 2002

Professional Bench/Manufacturing Up Close


Solder and Heat Issues for Lab-Created Moissanite

As use of this stone in fine jewelry grows, here are some tips for working with it at the bench


One of the more invasive and potentially damaging bench procedures for any gem is retipping prongs with the stone in place because of the heat involved. To test the limits of synthetic moissanite and its working characteristics when heat is required at soldering temperatures, we retipped a 14k gold two-tone solitaire ring with worn prongs using standard torch techniques. Here’s a summary of the procedure, results and some potential problems.

Retipping Using Easy Solder

1. The ring set with moissanite was thoroughly cleaned.

2. The top of each worn 14k white gold prong was filed flat.

3. The ring and stone were firecoated using a mixture of denatured alcohol and powdered boric acid and allowed to air dry.

4. The ring was generally preheated using a torch with a bushy flame. Note: While heating lab-grown moissanite, the material changes color. After it cools, the original color returns.

5. Individual fluxed chips of white gold easy solder were placed at the top flat part of each prong. Note: Hoover and Strong’s 14k white easy solder was used. It has a melting point of 1,240°F and flow point of 1,290°F.

6. General heat was applied again. After sufficient preheating, direct heat was applied to individual prongs, melting (but not flowing) the solder at the top of each prong.

7. Because the solder was melted and not flowed, and with the torch technique used, the solder retained a flattened shape.

8. Next the ring and stone were preheated. Slightly flattened 14k white gold beads were fluxed and placed on each prong top.

9. Using the illustrated torch technique, the beads were soldered into position in contact with the crown to the stone.

10. After the ring was allowed to air cool, it was submerged in pickling solution, rinsed and finished.

Results

After the ring was finished and polished, the stone was unmounted and inspected under magnification. No changes to the stone or damage were observed.

Retipping Using Hard Solder

The retipping procedure was done also using 20k white hard solder in place of 14k white easy solder. This isn’t common practice, but it provided an opportunity to test the limits of lab-created moissanite and extreme heat in close proximity. Note: Hoover and Strong’s 20k white hard solder was used. It has a melting point of 1,565°F and flow point of 1,615°F.

Results

After completing the procedure and removing the stone, this was observed:

A. Minor dark stains on the stone surface under two of the four prongs.
B. A small fracture under one prong (on the girdle).
C. Slight etching on the table and crown surfaces.

Ring Sizing and General Repair Requiring Heat

Several rings set with lab-created moissanite were sized up and down using standard torch techniques and hard solder. In addition, inferior worn posts were removed from stud earrings set with heart-shaped lab-created moissanite. New posts were torch-soldered in place using 14k white easy solder.

Results

After completing all procedures and removing the stones for inspection under magnification, no changes to the stone or damage were observed.

The Users Speak

Berkeley Grimball, owner of Grimball’s Jewelers, an American Gem Society store in Chapel Hill, NC, has sold lab-created moissanite jewelry for over three years. He says the store routinely sizes and performs general manufacturing with the jewelry and has experienced no stone damage or related problems when heating and soldering.

Daniel Ballard, PM West’s technical expert, recently supervised field testing at a production casting facility for stone-in-place casting using karat gold and lab-created moissanite. Using procedures common to the process, benchworkers
experienced positive results, with no changes or damage to the stone once unmounted.

Lab-created moissanite educational content is sponsored by Charles & Colvard. For general information related to Charles & Colvard Inc. and lab-created moissanite, call (800) 210-4367.

For information related to working characteristics of lab-created moissanite at the bench, call Mark Mann at (406) 961-4426 or (800) 210-4367, extension 251.

For information related to lab-created moissanite in-place casting, call Daniel Ballard at (800) 999-PLAT.

– By Mark B. Mann

Illustrations by Lainie Mann
©2002 Visual Communications

Copyright © 2002 by Bond Communications