Professional Jeweler Archive: Setting Princess-Cut Diamonds in 'V' Prongs

October 2002

Professional Bench/Defining Quality


Setting Princess-Cut Diamonds in 'V' Prongs

Knowing how to professionally set princess-cut diamonds with this method demonstrates another aspect of quality in your shop


We covered how to set princess-cut diamonds in prongs in the September 2002 issue of Professional Jeweler (pp. 73-76). This month the focus is on setting a princess-cut diamond in “V” prongs. Findings from Roseco, Dallas, TX, are featured in both articles.

Inspection, Job Analysis and Preparation

Barry Pizzolato of Designs in Jewelry Inc., Metairie, LA, first inspects the diamond for breakage or other potential challenges, such as a thin or wavy girdle or uneven diamond proportions. When he places the diamond into the platinum ring setting, he ensures the prongs are fully visible and that each corner of the diamond lines up with the center of each prong. If the diamond is slightly rectangular, he adjusts the prongs accordingly.

Preparing the Relief Portion of the Bearing

To determine where to cut the bearing, Pizzolato uses a fine pair of dividers and marks each prong at the level where the girdle will be seated. Each prong is marked at equal measurements from the top, from 1mm to 1.5mm. He uses a #6 or #7 ball bur to create a small pilot hole. The pilot is cut to 60% of the depth of the prong. Pizzolato suggests using a new bur for each setting.

Creating the Bearing

Pizzolato uses the same ball bur to hollow out below the pilot hole, burring down from the hole 2mm to 3mm. The angle of the hollow should match the pavilion angle of the diamond. Next he uses a #5 ball bur to perform general hollowing above the pilot hole. He positions the ball bur straight, burs slightly into the prong then raises up. The overall depth of the cut is 0.25mm to 0.5mm.

Pizzolato uses a #6 bud bur to cut a channel for the girdle of the diamond in each side of the prong. He positions it in the pilot hole and rocks it back and forth, cutting an indentation slightly wider than the width of girdle. The overall depth of the cut into the prong is 50% to 60%. The overall width of the cut from top to bottom is 1mm to 1.5mm.

Next he prepares all four prongs, constantly fitting his diamond and ensuring the points fit into the grooves that he’s cut. This approach ensures he doesn’t bur away too much metal. Once he’s satisfied with the fit, he removes all flashes of metal from each prong. Then he prefinishes and polishes the ring and places the diamond into position in the bearing.

Seating and Setting the Gemstone

Before bending the prongs over the diamond, he ensures:

  • The pavilion angle of the diamond matches the angle of the cut into the prong.
  • The cut of the pilot hole is slightly deeper in the central part of the prong to accommodate the diamond’s corners.
  • There is no visible space at or slightly below the girdle.
  • The diamond is level when placed into the bearing.

Pizzolato positions his notched modified flat-nose pliers at the top of the opposing prongs. The “V” portion of the opposing prongs fits snugly into each notch. He gently rocks the pliers back and forth, which bends each prong over the diamond to secure it in place initially. Next he positions the pliers on the other two opposing prongs and repeats the procedure. He carefully inspects each corner, ensuring the diamond is level and that it contacts all prongs equally. “Constantly inspect your work using a 10-power loupe because this is a critical step,” he says. Then he secures the diamond by bending each prong in two or three small incremental steps, inspecting the job throughout the process.

During this process, the portion of the prong that is bending will flare outward. He uses a prong pusher to push it back in. If the metal is thick and difficult to move with the prong pusher, he uses standard flat-nose pliers and grabs the innermost portion of each outside corner of the prong and gently squeezes.

Finishing

Using a #4 small barrette file, Pizzolato files the tops of the prongs flat. He ensures there are no sharp corners by beveling the two outer edges of each prong. When he’s finished, all outside walls have an equal wall thickness and are even and square. Next he uses a #40 flat bottom graver to cut an angle on the top of the prong toward the diamond.

To finish the prongs, he starts with #2 emery paper and progresses to 2/0 then 4/0 paper. Next he uses rubberized lilac finishing wheels from Gesswein. He prefers the knife-edge wheel (Gesswein product #1451359).

Procedure Summary

Setting a princess-cut diamond in a prepolished head using this process takes Pizzolato 15 to 20 minutes for an evenly proportioned and symmetrical 1-ct. diamond.

– by Mark B. Mann

Technical Contributions by Barry Pizzolato, owner of Designs in Jewelry Inc., Metairie, LA

For questions related to this process, contact Barry Pizzolato at (504) 888-0713.

The four prong heads featured in this article are from Roseco, Dallas TX; (800) 527-4490, www.roseco.com.

Illustrations by Lainie Mann
Visual Communications, (406) 961-4426
©2002 – Visual Communications



Setting Princess-Cut Diamonds in ‘V’ Prongs

A. The diamond is level and the tops of the prongs are slightly higher than the table.

B. The “V” prongs are snug and flush against the diamond. There is no flaring or cutaway of metal below the tops of the prongs.

C. A relief hole has been created in each “V” prong so no metal from the prong touches the point of the diamond. (Unable to view after the diamond is set.)

D. The “V” prongs have a small bright cut facing inward at the top.

E. There are no flashes of metal or tool marks on the prongs or ring.

Potential Problems to Watch for

Too much metal was removed at the bearing and the prong is thin, uneven and unstable.
The diamond was set too low in the mounting, minimizing its appearance.
The tops of the prongs have been filed too low, minimizing the ring’s wearability and weakening the setting.
The pilot hole, relief cut and bearing were not prepared properly. When this diamond was set, a corner was broken.

– by Mark B. Mann

Illustrations by Lainie Mann, Visual Communications, (406) 961-4426.
©2002 – Visual Communications

Copyright © 2002 by Bond Communications