Professional Jeweler Archive: Channel Setting Princess-Cut Lab-Created Moissanite

June 2003

Professional Bench/Manufacturing Up Close

Channel Setting Princess-Cut Lab-Created Moissanite

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

Successful channel setting of princess-cut lab-created moissanite (referred to from here on as just moissanite) requires an understanding of the material, careful preparation of the mounting and professional setting procedures. For this project, 2.5mm moissanite will be channel-set in a single row.

The combined crown and pavilion angles (profile view) of princess-cut moissanites averages 73.&Mac251; Their girdles are polished and sufficient for channel setting.

Preparation for Setting

Using a precision caliper, measure each moissanite. Organize the jewels for the project, largest in the center and graduating down to the smallest on the ends. For channel setting, the moissanites should not vary more than 1/10th of a millimeter in their outside dimensions and have closely matching crown and pavilion angles.
Align them table-down on a hard, flat surface next to one another. View the row from the side to confirm their proportions as shown below.

Preparing the Bearing in the Channel Walls

Use an automated burring system – such as the AllSet by Foredom – to create the bearings in the channel walls. This will allow you to quickly bur a level channel bearing at an even depth from the top and into the wall.

The AllSet (A) is attached to a standard #30 Foredom handpiece (B) with the channel guide (C). A 1.5mm 70° bearing bur (D) is used. The depth of the bearing from the top of the mounting is adjusted by turning the shaft-adjusting nut (E).

Next use the following procedure:

1. Measure the inside width of the channel wall. For 2.5mm moissanite, the inside width should be 2.0mm to 2.1mm.

2. Estimate the total depth of the bearing from the top of the channel wall and adjust the setting of the AllSet accordingly. For best results, the top of tables of the moissanite should be about 1mm below the top of the channel wall.

3. Anneal, prefinish and polish the mounting.

4. Use a 1.5mm 70&Mac251; bearing bur. Create the bearing and be sure to check the depth of the cut as you proceed. Your goal is to remove 0.20mm to 0.25mm of wall thickness from each side of the channel wall.

Setting and Finishing

5. Remove all metal fragments, filings and obstructions from the channel.

6. Place the moissanite into the newly created bearing. It should “snap” into place with very little resistance. If the moissanite moves easily at this stage, it’s too loose and will not tighten when finally set.

7. Apply gentle heat to the mounting and rub a piece of sprue wax over the top of the stones. The sprue wax will melt into the channel and temporarily “lock” the moissanite in place.

NOTE: The moissanites must not overlap one another. At this step, they should abut each other with contact at the girdles only.

8. File an angle on the top of both channel walls. The tallest part of the angle should be closest to the stones.

9. Select a small hammer and punch. The punch should be slightly wider than the channel wall. Lightly hammer the channel wall downward onto the moissanite by starting in the center of the row and working toward each outer edge. Hammer opposite walls through this process.

10. Repeat step #7 until the stones are secure in the mounting.

11. Steam to remove the wax and any filings that might be trapped between the moissanite and the channel wall.

NOTE: Be sure to remove filings that may have become trapped between the channel wall and the moissanite. Over time, they will be dislodged and the moissanite will loosen.

12. For final tightening, file another angle on each channel wall, this time about 15&Mac251; to 20.&Mac251; Hammer again and inspect.

13. File the top of the channel walls flat. The table of the moissanite should be even with the top of the finished channel wall. Finish and polish.

Charles & Colvard Ltd. sponsors this educational content. For general information on moissanite, call Charles & Colvard at (800) 210-4367. For information on working characteristics of moissanite at the bench, contact Mark B. Mann at (406) 961-4426 or (800) 210-4367, ext. 251;

By Mark B. Mann
Technical Contributions by Jeffrey Mathews of Jeffrey Mathews Designs, Dallas, TX

Photographs Mark B. Mann
Illustrations by Lainie Mann
©2003 Visual Communications

Copyright © 2003 by Bond Communications