Professional Jeweler Archive: Fabrication of a Wire Prong Assembly

February 2002

Professional Bench/Defining Quality


Fabrication of a Wire Prong Assembly for Round Brilliant Stud Earrings

Knowing how to accomplish this task demonstrates another aspect of quality in your shop


It was 1989 when I left Chicago and moved to Arkansas to accept a position at Underwood’s Fine Jewelry. Along with my new position came a new bench, a new pickle pot, new procedures and the two old things shown here.

I studied these tools for a while. Then, needing to get on with my new job, I dismissed them as unimportant and shoved them into the back of my new toolbox. In retrospect, the one thing I neglected to bring to my new career was a new attitude, for I suddenly found myself working in a store that placed heavy emphasis on craftsmanship and old-world jewelry-making techniques. They didn’t even order crowns (Y’all, that’s southern – genteel – talk for heads or prong assemblies) from manufacturers – it was my job to fabricate them.

After several futile attempts at fabricating a prong assembly, I took a closer look at those two old things. Guess what? Cha-ching! They turned out to be tools designed to facilitate the fabrication of a wire prong assembly.

This article focuses on the fabrication of a prong assembly to set round brilliant gemstones into stud earrings.

Understanding the Tool

The tool has a slight taper at each end, with grooves milled into each taper. One end has 12 grooves and is designed to create 3-, 6- or 12-prong wire assemblies.

The opposite end, shown here, has eight grooves and creates 4- or 8-prong wire assemblies.

Using the Tool

The four-prong wire assembly being fabricated is for a 1.50-ct. round brilliant diamond. Because it’s for a stud earring, I will use 1.25mm diameter wire instead of 1.35mm, which would be more common for a ring setting.

Cut equal lengths of wire 20mm long and lay them into the grooves. The prong wires are secured with binding wire, wrapped several times and tied off.
The tool will hold the prong wires securely while they are soldered at the part of the base where they come together. Don’t try to solder too close to the tool. Benefits:
  • The tool simplifies the soldering process.
  • The prong wires are held at preferred 70&Mac251;angles.
  • The prong’s wires are spaced precisely.

The diameter of wire used to fabricate prong assemblies depends on three factors:
  • The size of the gem that will be set into it.
  • The number of prongs.
  • The application for the finished prong assembly.

The wire for a four-prong assembly is thicker than one with six prongs. Likewise, an earring setting needn’t be as heavy as one for a ring. Keep a written log of prong assemblies you create. Include the wire diameters, use of the assembly, quality of the metal and the results.

Upper and Lower Gallery Wires

After soldering the prong wires, make the upper and lower gallery wires. I use round wire the same diameter as the prongs and run it through a rolling mill until it’s rectangular. I form the wires with round-nose pliers and solder the gallery wires closed with hard solder.

The diamond is 7.3mm, the outside diameter of the upper support is 6.6mm and the lower support is 4.6mm. Also:
  • The outside diameter of the upper gallery support should be 10% smaller than the gem.
  • The lower gallery wire should fit snugly inside the upper gallery.
  • Both support rings should be flared slightly. I like to use a dapping punch for this.

Bench Trick

Here’s a simple modification for truing up your gallery wires. Select a standard mandrel. Taper the base of the screw’s head and the top of the base of the mandrel’s shaft. Place the gallery wires individually between the screw and the base of the mandrel and spin. The tapered screw heads will create a mini-self-centering lathe, enabling you to file or sand the gallery wires perfectly round.

Embellishments

The upper and lower gallery wires are a perfect place to add a special touch that communicates “this piece was handmade.” If you choose to embellish the wires, it should be done before soldering the assembly. Use a combination of a fine millgrain wheel
and a small sharp beading tool to embellish the gallery wires.

Burring and Fitting

Small notches need to be cut into the gallery wires to accept the prongs.

Use a small cylinder bur the exact diameter of the prong wire to create the notches in the upper and lower gallery wires. Always position one of the groves directly over the solder seam in each gallery wire.
  • The notch’s depth should be 1/3 of the gallery wire’s diameter.
  • Alignment is critical when fitting gallery wires and prongs.
  • Soldering gallery wires and prongs is done with minimal hard solder.

Bench Trick

You can use instant glue to adhere the two supports together. I then glue both supports to the tip of my prong assembly-manufacturing tool. The tool can be used as a guide to cut the notches in the gallery wires.

The Crowning Touch

Decorative elements added between the supports can set your custom prong assemblies above all others.

Though this prong assembly is an earring, similar pieces are very popular in antique-style rings. Your customers may make suggestions for the design of the small inserted pieces. Some popular choices include initials, hearts and religious symbols.

The Finished Earring

Final Notes

  • Use minimal amounts of medium or easy flowing solder to add the decorative elements.
  • Roll your solder very thin so you use smaller amounts.
  • Notice the earring post is positioned high of the center-line. This helps an earring not to droop.
  • Always use good quality findings for custom earrings. This post measures 0.85mm in diameter and 11mm in length.

– By Tom Weishaar, JA® Certified Master Bench Jeweler™, Shop Manager, Underwood's Fine Jewelry, Fayetteville, AR

This information is required for the third level of the JA® Bench Jeweler Certification™ program. The prong assembly manufacturing tools featured in this article are available from Frei & Borel at (800) 772-3456.

© 2002 Jewelers of America
Illustrations by Lainie Mann – Visual Communications


The JA® Professional’s Guide to
Fine Jewelry Craftsmanship

Fabricating Prong Assembly for Round Stud Earrings

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


Professionally Hand-Fabricated Stud Earrings

A. The solder joints are complete, clean and free of visible excess solder, pits and cracks.

B. The prongs are symmetrical and evenly spaced.

C. The upper and lower gallery wires are evenly spaced.

D. The upper and lower gallery wires are notched and the prongs are evenly spaced and soldered into them.

E. The finish is even, smooth and free of tool marks.

F. When you view the assembly from the top, you see no metal with the exception of the prongs.

Potential Problems to Watch for

This prong assembly was poorly made; gallery wires and prongs are unevenly spaced and lack symmetry.
The wire diameter selected for this earring was too small; through normal wear, the prongs can become deformed, causing the gemstone to loosen and become lost.
This prong assembly was fabricated with little attention to detail; tool marks remain visible to the unaided eye.
The prong assembly is too tall and the post is centered on the back of the assembly. This earring will droop and never be positioned properly on the ear.

This information is required for third level of the JA® Bench Jeweler Certification™ program. For information, call JA at (800) 223-0673 or visit www.jewelers.org.

©2002 Jewelers of America
Illustrations by Lainie Mann – Visual Communications

Copyright © 2002 by Bond Communications