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September 1999

For Your Staff: Selling Quality

Sizing a Platinum Ring

Knowing the techniques to size platinum rings professionally demonstrates another aspect of quality for your shop and store

Ring sizing – up or down – is the single most frequently performed repair in a jewelry store. The ability to perform this procedure skillfully is essential to your success in selling and repairing rings. In fact, your offer to size a ring while a customer waits can be the deciding factor in a sale. But the job must be done with the utmost quality.

As more and more platinum jewelry is sold, it's important to know the particular techniques professionals use to size platinum rings. This installment of the "JA Professional's Guide to Fine Jewelry Craftsmanship" offers technical information on how to size platinum rings properly. It also describes the details and potential problems if the work is done incorrectly.

We'll describe two sizing methods: one using a welding technique, the other using a soldering technique. The type of platinum alloy in the ring determines which method is appropriate. Following are the essential quality features for sizing a platinum ring:

  • Proper fit.
  • Invisible seam.
  • Even shank thickness with little dimensional loss.

Scenario One
First, we'll size a 900/100 platinum/ iridium ring one size smaller using the welding process. Cut the ring to remove 2.54mm from the shank, usually at the bottom, assuming this won't damage or remove any quality or manufacturing marks or engraving.

  1. Bend the ring together so the ends meet. When welding or soldering platinum, take care to have a precisely fitting solder joint with no visible gaps or openings.
  2. File a chamfer around the solder joint with a three-square file (top illustration).
  3. Roll the piece removed from the shank until it's paper thin. Wedge a portion of this piece into the chamfered groove so it sticks out about 1mm all the way around the cross-section of the shank (bottom illustration).
  4. Wearing special # 5 welding goggles, heat the joint and melt the platinum all around the seam so it fills the gap. Use enough heat to create a metal bond through the entire seam so there's no break in the metal-to-metal contact (see illustrations below). Be careful! Too much heat from the torch will melt the ring at the joint.
  5. Gently file away the excess metal around the seam.
  6. Round the ring, check the size for accuracy and make any necessary adjustments.
  7. Burnish, file, sand, polish and clean the ring so no scratches, pits or tool-marks remain.

Scenario Two
In this example, we'll size a 950/50 platinum/cobalt (pt/co) ring one size smaller using the soldering process. You must use the soldering method (rather than welding) to size platinum/cobalt rings. A common magnet strong enough to pick up tools let's you separate pt/co from other platinum alloys.

  1. To prepare the sizing joint, follow steps 1 and 2 from Scenario One.
  2. Instead of filing a chamfer, wedge a piece of 1700 platinum solder into the seam. The cross-section of the solder should be smaller than the cross-section of the ring so no solder spills onto the outside of the seam (see below).
  3. With a sharp oxidizing flame, heat the ring at the sizing area until the solder melts, flows and bonds.
  4. Unlike other platinum alloys, pt/co oxidizes during soldering. Remove this oxidation by simple pickling or by polishing.
  5. Gently file away any excess metal around the seam.
  6. . Round the ring, check the size for accuracy and make any necessary adjustments.
  7. Burnish, file, sand, polish and clean the ring so no scratches, pits or tool-marks remain.

Special Note
Jewelers of America and the Platinum Guild International have produced a new 30-minute video featuring platinum fabrication skills. In it, JA® Certified Master Bench Jewelers™ demonstrate platinum welding and soldering techniques in a variety of applications and in great detail. They also reveal a series of bench tricks used during platinum fabrication. To buy a copy, call Jewelers of America at (800) 223-0673 or Platinum Guild International at (949) 760-8279.

Chamfer filed around the solder joint
Piece of platinum is wedged in the gap
Cross section of an incomplete joint
Cross section of a complete joint
Piece of platinum wedged in gap

Characteristics of Professional Platinum Ring Sizing

  1. No visible solder seam or line where the ring was welded or soldered.
  2. Dimensions are all equal from side to side and top to bottom.
  3. Shank is not too thin.
  4. No visible tool marks or any unfinished areas.
Visible Solder Seam: There should be no visible seam or line once the ring has been sized.
Uneven Dimensions:There should be no uneven dimensions from side to side and/or top to bottom.
Significant Shank Reduction: The width and depth of the shank should not be significantly reduced from their original dimensions.
Broken Joints: During normal wear, incomplete solder and weld joints will result in a "broken" shank – and your customer's loss of confidence in your work.

– by Jurgen J. Maerz JA® Certified Master Bench Jeweler™, Director of Technical Education, PGI and Mark B. Mann Director of Professional Certification, Jewelers of America

Illustrations by Lainie Mann - Visual Communications

Copyright © 1999 by Bond Communications.


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