Professional Jeweler Archive: Reconstruction of a Box Clasp

July 2001

For Your Staff/Defining Quality

Reconstruction of a Box Clasp

The ability to achieve smooth and failure-proof operation demonstrates another aspect of quality in your shop

Box clasps are used for everything from in-line diamond bracelets, strands of pearls and beads to sterling silver charm bracelets. Regardless of the value of the material, these clasps must perform the same function – securing jewelry. This installment will review box clasps and their reconstruction.
Characteristics of a Worn Clasp

1. The tongue’s metal is worn and excessively thin.

2. The depression tab is sharp or has broken off.

3. The tongue has cracks.

4. The tongue doesn’t spring back into position.

5. The tongue is narrower than the opening.

6. The secondary security device is loose and not functioning properly.

Reconstructing a Worn Clasp

When the wear is significant, it’s best to replace the box clasp. When not, reconstruction is possible. We illustrate four problems in boxes on the left side of this page and the next one. To the right of the boxes are solutions.

Replacing the Tongue

The tongue is broken, but its width and thickness are sufficient for many more years of wear. Here’s how to resolder it.
  1. File each end of the broken clasp.
  2. Realign the two pieces and tack weld them into position using an electronic tack welder. This frees you from having to use tweezers or holding devices that would interfere as heat sinks during soldering.
  3. If you have no tack welder, realign and solder the pieces using easy-flow solder and third hands as holding devices.
  4. Solder and refinish.
Replacing the Tab

Tab was broken off or worn down and is sharp, making it difficult to operate. Here’s how to replace it.

  1. Saw an appropriate size disc from 1mm karat gold sheet.
  2. Slightly dome it.
  3. Using a small ball burr, remove a small amount of metal at the center of the bottom.
  4. Melt a piece of easy-flow solder into the indentation.
  5. File the top of the plunger.
  6. Solder the disc onto the plunger.

Adjusting the Security Device

The figure eight is out of adjustment and should be refashioned. Here’s how.

The secondary security device is a figure eight that hinges from a single position and locks into place over a bead that’s soldered to the box. It often needs to be readjusted.

  1. Using round-nose pliers, readjust the figure eight so it snaps over the locking bead.
  2. If the wire feels soft, lay it on a steel block and lightly tap it with a chasing hammer to harden it.
  3. Repeat step 1.
Reconstructing the Entry Side of the Box Clasp

The opening side of the box clasp is worn, and the tongue won’t lock into position. Here’s how to fix it.

  1. Remove the worn opening by filing.
  2. Fashion a new piece by sawing.
  3. Solder the new piece in place.
  4. Adjust the tongue to work with the new piece.

© 2001 Jewelers of America Inc.
Illustrations by Lainie Mann – Visual Communications


The JA® Professional’s Guide to Fine Jewelry Craftsmanship

Reconstruction of a Box Clasp

By Mark B. Mann, Director of Trade programs, Jewelers of America


Professionally Reconstructed Box Clasp

A. The tongue freely springs back into position after being depressed.

B. The tongue slides easily into the box and locks into position.

C. When the tongue is depressed, it’s easily removed from the box.

D. The depression tab is even, smooth and substantial.

E. The thickness of the tongue is ample.

F. The tongue’s width is even with the width of the opening in the box.

G. The figure eight security feature swings freely and snaps into position.

H. The wire portion of the figure eight is easily released from its locked position.

Potential Problems to Watch for

This tongue is too narrow for the box and will likely open while being worn.

The tongue is too thin and will break eventually.

A tongue that doesn’t spring back into position offers no security and should be replaced.

This depression tab is excessively worn and sharp, making it difficult to release the tongue from the box.
© 2001 Jewelers of America Inc.

This information is required for all levels of the JA® Bench Jewelers Certification™ program.

For information about JA® Bench Jewelers Certification,™ call JA at (800) 223-0673 or visit

Illustrations by Lainie Mann – Visual Communications

Copyright © 2001 by Bond Communications