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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. |
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2. Standard prongs with a similar
prong for the point. |
| 3. Standard prongs with a "V"
prong for the point. |
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4. "V" prongs only (marquise
only). |
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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. |
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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.
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Remove the Flashing
Use a flat-bottom graver to remove the flashing of metal the
bur created next to the prong.
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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.
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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.
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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.
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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.
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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
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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.
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Potential Problems to Watch For |
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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.
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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.
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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.
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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).
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Upper Part of Prong Doesn't Touch Crown
All prong tips should be in full contact with the stone's
crown.
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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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