Color Considerations When Setting Gemstones

SETTING CONSIDERATIONS
FOR COLOR
Ann Cahoon
ann@anncahoon.com

Sunday, June 20, 2010

SOME FUNDAMENTALS....


GET COMFORTABLE IDENTIFYING
YOUR GEMSTONES.......



• Because you need to know what special care a gem might
require.



require.

• Because you may need to apply a value to something.



require.


• Because you need to know when to call in an expert- this could
be anyone from your supervisor, to an outside, independent
gemologist.



require.


• Because you need to know when to call in an expert- this could
be anyone from your supervisor, to an outside, independent
gemologist.

• Because you need to know when to say “NO!”


GET IN THE HABIT OF SCRUTINIZING
EVERYTHING THAT COMES ACROSS
YOUR BENCH.......


YOUR BENCH.......

• Know what you’ve got before you start any work- this
includes design! Knowing what you’ve got lets you know
what you can do.


YOUR BENCH.......

• Know what you’ve got before you start any work- this
includes design! Knowing what you’ve got lets you know
what you can do.

• By examining every stone with a loupe, or under the
microscope, you can identify potential problem areas
before they become problems.


YOUR BENCH.......

• Make notes about damage and inclusions.


YOUR BENCH.......


• Note distinctive qualities and characteristics.......


YOUR BENCH.......


• Note distinctive qualities and characteristics.......

• Color change, zoning, silks? All these qualities are
important indicators of what a mystery material could
be.


YOUR BENCH.......

• Observe the quality of the cutting.


YOUR BENCH.......


• Thin girdle, chubby pavilion, super high crown? These
details will inform how you build or select your
mounting, as well the procedures you can use when
you set.


YOUR BENCH.......


• Thin girdle, chubby pavilion, super high crown? These
details will inform how you build or select your
mounting, as well the procedures you can use when
you set.

• Not only can these particular details be helpful at the
bench, they can also inform the way you do business.


“TAKE NOTE” MEANS WRITE IT
DOWN!

• Your own notes and experiences mean more to your work at
the bench than anything else- take the time to keep a
notebook or daily log.

• Because your working style is unique, you can often ﬁnd the
solution to a problem in a problem that you have already
solved. This applies to more than just stone setting!


GEMSTONE
CHARACTERISTICS- BEYOND
RED, WHITE, AND BLUE
..... and maybe a few things you should know about those, too.


ALEXANDRITE

• Hardness = 8.5

• Tolerant of ﬁles/abrasives and polishing.

• Tolerant of steam and ultrasonic.

• One should use extreme care in handling because of rarity and
expense, rather than fragility- it is, in fact, durable enough for
daily wear!


ALEXANDRITE

AQUAMARINE
• Hardness = 7.5 to 8

• Damage is likely from most bench processes- ﬁles and
abrasives, polishing, steamer and ultrasonic.

• Take particular care when cutting seats to avoid pressure
points and rough surfaces.

• Even though it is relatively hard, it is fragile- set it with more
care than the Mohs number might indicate.


AQUAMARINE


CHALCEDONY


• Use care in preparing the mounting, uneven pressure often
causes chipping.

• Even though chalcedony is typically a cab, it still requires a light
touch to avoid damage.


CHALCEDONY

EMERALD
• Hardness = 7-8


• Damage is also likely from wear!

• Cut seats and prep the mounting to avoid pressure points.

• Design the mounting to protect the gem as much as possible
while still being realistic about setting it! Alloy choice is
important.


FELDSPAR
• Hardness = 6 - 6.5

• Includes sunstone, moonstone, and labradorite.

• You will see both cab and facetted material.


• Mounting should fit the profile of the stone as closely as
possible. Even as a cab this material is delicate- don’t assume
your cab bezel is ready to set without modification. Always
avoid direct pressure.

MOONSTONE

GARNET
• Hardness = 6.5 - 7.5

• Damage is possible from many bench processes- ﬁles and
abrasives, and the steamer.

• Tolerates polishing and the ultrasonic.

• Interesting to note that chemically, garnets can be quite
different from one another.

• While fairly tough, care should be taken to cut conforming
seats to avoid pressure points.


GARNET MATRIX

MORGANITE


• Be careful to properly identify this material- confusion with
other pink stones (ie spinel and sapphire) can result in
improper handling.

• Cut seats to avoid pressure points.

• Although it is relatively hard, it is fragile like its beryl cousin,
emerald.

MORGANITE


OPAL
• Hardness = 5 - 6.5


• Notoriously difﬁcult to set- ask yourself if your alloy choice
and mounting design are feasible.

• Consider the use of alternative materials for bezel/prong
pushers. Brass stock is readily available in most shops and can
be quickly fashioned into a forgiving setting tool.

• When possible, also protect the stone with the setting.

COOBER PEEDY OPAL MATRIX

KOIROIT OPAL

PEARL
• Hardness = 2.5 - 4

• Damage is certain from most bench processes- ﬁles and

• For reasons of practicality, most pearls are drilled and set on a
post with glue. If you must set a pearl traditionally, consider the
use of alternative materials for bezel/prong pushers. Brass
stock is readily available in most shops and can be quickly
fashioned into a forgiving setting tool.


PEARL IN SHELL IT WAS
HARVESTED FROM

PERIDOT

• Hardness = 6.5 -7

• Damage is possible from many bench processes- ﬁles and
abrasives, and the steamer.

• While peridot is relatively sturdy, they will still chip more
readily than corundum or diamond, so some care should be
taken when pushing a prong or bezel down onto the stone.


SPINEL

• Hardness =8

• Damage is possible from relatively few bench processes- ﬁles
and abrasives,polishing, the ultrasonic and the steamer can al
be used safely.

• One of the few materials other than the usual “red, white, and
blue” suspects that can tolerate fairly aggressive setting
techniques.


SPINEL OCTAHEDRONS

RED SPINEL

RUBY AND SAPPHIRE
• Hardness =9

• Damage is possible from relatively few bench processes- ﬁles
and abrasives,polishing, the ultrasonic and the steamer can al
be used safely.

• Much corundum is cut with “big bellies” (often asymmetrical)
which must be accommodated in the setting process- having
the right burs on hand, as well as plenty of material south of
the girdle are both critical to success.


RUBY


SAPPHIRE

TANZANITE
• Hardness = 6-7


• Scratches, chips and abrades very, very easily during the setting
process.

• Seats must be cut accurately to avoid pressure points and
stone breakage.

• Choose an alloy that will minimize stress on you and the stone
during setting.

TANZANITE

TOPAZ
• Hardness =8

• While it tolerates polishing well, ﬁles and abrasives, the
steamer and the ultrasonic may all cause damage.

• The stone has a tendency to cleave (isn’t that a refreshing way
to say break?)

• Despite it’s relative hardness, it is fragile due to one direction
of perfect cleavage.

• Cut seats accurately to avoid pressure points, and select a
malleable alloy. If practically possible, thin prongs or bezel wall.

TOURMALINE
• Hardness = 7 -7.5


• Often seen in long narrow cuts with steep pavilion angles
which can be prone to breakage- seats should be cut to have
good conformity to avoid issues.

• Exercise particular care with bi-color stones.


TOURMALINE

• Keep inexpensive samples on hand for potentially
destructive testing- ie response to abrasives.

• Practice on cheap stones.

• Label your stuff.


DESIGN

• Consider a bezel in place of prongs.

• Replace a few heavy prongs with many light ones.

• Consider carving your mounting in wax and cutting seats in
this softer, more forgiving material.

• Select an alloy that works for you not against you.


A FEW NOTES ABOUT
ALLOYS
• 14 K yellow: a standard benchmark to which • 22 K yellow: have you ever set in butter?
other alloys are compared, moderately easy
to set. • Palladium/ Pd 950: sets very easily until work
hardening (which happens relatively quickly),
• 14 K white: hard and springy. prong weight should be increased.

• 18 K yellow: easy to set. • Platinum 900 Iridium: easy to set.

• 18 K nickel white: very hard to the point of • Platinum 950 Cobalt: brittle in comparision to
being physically demanding. other platinum alloys.

• 18 K palladium white: easy to set- while • Platinum 950 Iridium: easy to set, work
harder than 18 K yellow, it is slightly easier to hardening is important for adequate security.
set than 14 K yellow.
• Platinum 950 Ruthenium: rigid and difﬁcult to
• 18 K green: even softer than 18 K yellow. set.


TOOLS AND EQUIPMENT


GRS BENCHMATE

GRS BENCHMATE

• Multiple adjustments allows work to always be at correct
angle.

• Holds a variety of attachments from soldering set-ups to
shellac pads, even insulated ring clamps.


GRS INSIDE RING CLAMP

GRS INSIDE RING CLAMP

• Comes with six plastic arbors that allow for large variety of
rings to be held while setting stones.

• Multiple adjustable angles of GRS benchmate allows for ease
of stone setting.


JETT SETT

• Simple alternative to shellac.

• Offers great support to
delicate work .

• Not appropriate for stones
with thermal sensitivity.


NON-TRADITIONAL FIXTURING


GRS ACROBAT STAND FOR
MICROSCOPE

• Allows for precise
positioning and holding of
position

• Eases fatigue of user, since
you are always in a
comfortable position.


MICROMOTOR POWER
SUPPLY

• Drives various styles of
handpieces.

• high speed, low torque

• mid speed, high torque

• hammer handpiece


MICROMOTOR HANDPIECE

• 35,000 plus rpm’s allows for
precise cutting with burs.

• No ﬂexible shaft allows for
easy manipulation without
fatigue.


CHOOSING THE RIGHT BUR

• Many (most!) colored stones are not cut
even remotely like diamonds.......

• This means re-examining our approach to
cutting seats.

• Keep a selection of bud and ball burs on
hand.

• Reference your bur directly to your stone.

• Assume a two tool, multi-step cutting
process.


BALL BUR USED FOR FLUSH
SETTING

BALL BUR FOR FLUSH
SETTING

• Allows angle of handpiece while cutting “seat” to be far less
important.

• Speeds work.

• Stones line up and sit level with top of work much more easily
than when using hart burs.

• Accomodates non-diamond cut stones.


CONSIDER YOUR CORNERS
• Avoid exposed corners- the reason you don’t want to set
them is the same reason you don’t want to leave them
exposed!

• Use a ball bur to ease the corners as you always would for a
V-tip or bezel.

• Make sure that you are creating a “pocket” in which the
corner will “ﬂoat”.

• Ease out of that under cut with a smaller ball bur to allow for
a gentle transition- if you don’t touch up that edge you can
create a pressure point.

CHANGE UP YOUR SETTING TOOLS


CONSTRUCT PUSHERS AND BURNISHERS OF
MORE FORGIVING MATERIALS

• Consider brass as an alternative to your
traditional steel pushers and burnishers.

• Modify hardwood dowels.

• Even plastic/acrylic can be used.

• Keeping graver handles and pin vises on hand
makes tool development an option that is
always convenient.


PROTECT YOUR STONE FROM YOURSELF


RE-THINK FINISHING

• Just take the cup burs off your bench.

• If you don’t already, add a 6 and an 8 cut “safety edge” three square file.

• Switch from silicon carbide to pumice for all post setting clean up- with a hardness of 6, it’s safe on
many materials.

• Get in the habit of pre-finishing all items before sitting down to set.

• Add 1“ muslin buffs to your flex shaft finishing materials, and use only with rouge (Mohs 5.5 - 6.5)
and other non-cutting compounds.


A FEW FINAL THOUGHTS

• Avoid rushing- as the last step, setting is often done at the last
minute.

• Keep reference materials easily accessible.

• Expect the worst....... handle all colored gem material with
caution. We all know that the “best case scenario” is ﬁction!

• Give yourself lots of opportunities to practice and hone your
skill.


RESOURCES

• Gemstones of the World, Walter Schumann

• Working with Gemstones, Arthur Anton Skuratowicz and Julie
Nash

• AGTA’s Retail Jewelers Reference Guide


THANKS!
Ann Cahoon
ann@anncahoon.com


Color Considerations When Setting Gemstones

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