Professional Jeweler Archive: Finishing the Inside of a Platinum Ring With 3M Abrasives

December 2003

Professional Bench/Tool Tips

Finishing the Inside of a Platinum Ring With 3M™ Abrasives

Jeffrey Mathews reveals his finishing techniques for the inside of a platinum ring using an assortment of abrasive products

1. Jeff Mathews has developed a process for polishing the inside of platinum rings using 3M™ abrasive technology. To illustrate how he performs the job, I follow his procedures using this hand-fabricated flat platinum band. Tool and forming marks are easily visible. The quality and identification marking has been completed.
2. After welding the ring and rounding it, I use several grades of 3M Imperial Micro-Finishing film adhered to a sheet of glass to true and pre-finish the sides of the ring band.
3. For the inside of the ring, Mathews advises using a 3M Trizact abrasive band of A80 grit mounted on a drum arbor mandrel. The 3M A80 grit is equivalent to 220 grit from other companies.

3M Trizact abrasive products feature a surface composed of tiny pyramid-shaped aluminum oxide abrasives in several grits that uniformly and evenly remove material. The Trizact band worked quickly and uniformly, and it didn’t remove a noticeable amount from the surface. Often with traditional sandpapers, the abrasive “pebble” will break away from the paper and introduce newer deep scratches. Trizact technology eliminates this concern.

4. Next Mathews advises using three grades of 3M diamond flex bands, which are metal-bonded and resin-coated. They remove material evenly and efficiently. He uses grits equivalent to 800, 1800 and 2600. To lubricate this part of the process, Mathews uses Bur-Life. When starting with a new flex band, he first dresses down the resin surface coating. He’s used the same diamond flex bands routinely for over a year.
5. Then he advises using five grades of 3M Imperial Micro-Finishing Film. He cuts the strips in 1/2-in. widths and wraps them over a diamond flex band mounted on an arbor mandrel. The flex band provides a hard, flat backing for the adhesive-backed microfinishing film.

The five grades of film I used are listed according to their grit and color: #1) 400, green; #2) 600, orange; #3) 1,200, blue; #4) 2,500, lavender; and #5) 3,500, gray. In this photo I’m using the 400 grit microfinishing film that is step #1 in the process.

6. I use the 1200 grit microfinishing film that is step #3 in the process. Notice the improving luster and how smooth it’s becoming.
7. For the last steps, Mathew’s advises using 3M Diamond Lapping Film with a grade of 3 microns (pink), then buffing it with Foredom’s White Platinum rouge (6,000).
8. The result is superior. The inside of the ring is flat, even and highly polished. The surface is hardly reduced in dimension, and the quality marks remain easily visible and undistorted. This process is good also for bicolor shanks of platinum and gold alloys because it works evenly with both alloys.

3M sponsored this installment of Tool Tips. For information on 3M products or for a list of distributors, call Rich Bohr at (602) 432-5547. For questions on this process, contact Mark B. Mann at (406) 961-4426 or

By Mark B. Mann

Technical Contributions by Jeffrey Mathews of Jeffrey Mathews Designs, Murphy, TX

Photographs by Mark B. Mann

©2003 Visual Communications

Copyright © 2003 by Bond Communications