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December 1999

For Your Staff: Selling Quality

Ship Shape

Knowing how to professionally set marquise and pear-shaped stones in prongs demonstrates another aspect of quality in your shop

Marquise and pear-shaped gemstones must be set in prongs properly to safeguard them. This installment of the JA® Professional's Guide to Fine Jewelry Craftsmanship deals exclusively with "diamond-proportion" marquise and pear shapes and the stone-setting features associated with them. Next month we'll cover marquise and pear-shaped gems cut to other than diamond proportions.

It's extremely important to consider the point(s) of the stone when setting and handling these cuts and to carefully plan and execute the setting. Careless setting and handling can damage the stone.
Four head-with-prong configurations are commercially available for pear and marquise stones and are illustrated below.

by Mark B. Mann, Director of Professional Certification, Jewelers of America

Styles of Prong Configurations
1. Standard prongs with no point prong.

2. Standard prongs with a similar prong for the point.
3. Standard prongs with a "V" prong for the point.

4. "V" prongs only (marquise only).


Setting Procedures Associated with Style 3
The most common prong arrangement for rings worn daily is style 3 (standard prongs with a "V" prong at the point). This offers the best security over time. Procedures for setting pears or marquise are very similar, given the shape of the stones and the points. To illustrate related features of stone security and safety, here is an overview of how they are typically set.

Bur a Seat

Once you've determined the final position of the stone within the head, use a small setting bur to create a "seat" in the side prongs. Prongs are burred individually at the same location, assuming the stone's girdle is of even dimension and proportion.

Remove the Flashing

Use a flat-bottom graver to remove the flashing of metal the bur created next to the prong.

 

Create a Seat in the Point Prong

Use a small ball bur or hart bur to create a "channel" or seat into which you can set the point of the stone.

Open the "V"

Use a small bud bur, ball bur or drill bit to open-up the area at the junction of the "V" prong so no part of the stone's point touches the prong.

Shape the Point Prong

Complete prefinishing, making sure:

  • The stone will be level when set.
  • All tool marks are removed.
  • The final shaping of the point prong is done and the head is prepolished.

Set the Stone

Set the stone by:

  • Placing it in its seat and partially bending the back two prongs over incrementally and one at a time (see #1).
  • Ensuring it is level through the process.
  • Partially bending the central two prongs (#2).
  • Fully bending the back two prongs (#3).
  • Fully bending the two central prongs (#4).
  • Shaping and matching the prongs. This also can be accomplished before setting.

Final setting and final finish.

Illustrations by Lainie Mann – Visual Communications

Make absolutely sure there is no contact between the point of the pear or marquise stone and the point prong, which would cause the point to chip, fracture or break during normal wear. The difficulty with this quality feature is you cannot see whether the point contacts the prong unless you remove the stone from the setting.

Contributions for this procedure from Wayne Lenkeit and Jeffrey Mathews, JA certified master bench jewelers.


To All Bench Jewelers: JA® Masters in Motion™

Want to brush up your fancy stone setting techniques? At the JA/Rio Grande "Masters in Motion" program, JA Certified Master Bench Jeweler Jeffrey Mathews will demonstrate methods of setting marquise and pears (and other fancies) in prongs. This event will be held in conjunction with the Rio Grande Catalog in Motion tool-and-equipment showcase at the Hilton Hotel Feb. 4-6 in Tucson, AZ.

Live video cameras will capture every nuance of Jeff's technique, with simultaneous playback for easy close-up viewing. Questions are welcome.

Attendance is free and seating for about 80 is available on a first-come/first-seated basis throughout the event. For a schedule of demonstrations, call JA at (800) 223-0673.


The JA® Professional's Guide to Fine Jewelry Craftsmanship Marquise and Pear-Shape Stone Setting

By Mark B. Mann
JA Director of Professional Certification

The stone is level, tight and secure.

  • A. All prong angles are between 65° and 75°.
  • B. Prong contact ranges between 30% and 50% and is consistent from prong to prong.
  • C. Prong height ranges between 60% and 80% and is consistent from prong to prong.
  • D. The removal of metal from the prong for the bearing is not less than 40% or more than 50%.
  • E. The flashing of metal has been removed from the prong where the bearing has been prepared.
  • F. The stone and point prong are in contact, but the extreme point of the stone is not in contact with metal from the point prong (unable to see after the stone is set).
  • G. There are no chips, abrasions or damage to the stone as a result of the setting process.
  • Potential Problems to Watch For

    Visible Space Between Bearing and Stone

    There should be no visible space between the stone and the seat prepared for it at or near the girdle.

    Stone Trapped Between Upper Gallery Wire and Prong Bent Over Crown

    The stone should be secured in its seat, not "trapped" between the upper gallery wire and the overly bent prongs.

    Over-Burred Prongs

    The prongs should have at least 50% of their original thickness. No metal "rag" should show after creating the seat for the stone.

    No Contact at Point Prong

    This cross-section view shows no contact between the point of the stone and the point prong (unable to see once the stone is set).

    Upper Part of Prong Doesn't Touch Crown

    All prong tips should be in full contact with the stone's crown.


    For information on setting round brilliants in prongs, see Professional Jeweler, February 1998, pp. 181-184.

    Illustrations by Lainie Mann – Visual Communications

    Copyright © 1999 by Bond Communications.



     

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