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To cast or fabricate stone setting


#1

Hello,

This is my first post here. I’m a glorified hobbyist jeweler and I
humbly turn to the collective expertise of this outstanding group
because I’m in over my head.

A friend has a 18x15x11 deep pear amethyst that he wants me to set
in a silver pendant for him. The stone has a visible inclusion near
the point that looks like a few straight lines when viewed from one
direction, but appear as planes when turned 90 degrees. I don’t know
enough to understand the implications of this for setting the stone.
It also has a rather big belly and the pavillion angle is rather
large. I tend to avoid stones cut like this when I buy for myself,
so I don’t have much experience making seats for big fat slopes like
this stone has.

He wants a ‘solid looking’ setting, i.e., bezel walls. My instinct
is to fabricate, but I never really learned to carve wax, so I
fabricate almost everything I make. What would you do with a stone
like this? Thanks in advance for your thoughts,

Zachary Androus


#2
The stone has a visible inclusion near the point that looks like a
few straight lines when viewed from one direction, but appear as
planes when turned 90 degrees. 

Sounds like you describing a feather. It is unusual for amethyst to
have this kind of inclusion, unless someone was tried to set this
stone before. My advice would be to make sure that the rest of the
stone is not under strain. Polariscope is a good tool for this. If
you
do not have one, ask some of the gem guys to take a look at it.

leonid surpin


#3

Fabricate, you did say Silver? Casting would be to time consuming.
The bezel punch would work well. Just my idea. Thanks Johneric


#4
The stone has a visible inclusion near the point that looks like a
few straight lines when viewed from one direction, but appear as
planes when turned 90 degrees 

Zachary, you’re setting a big ol’ piece of glass that’s already
cracked. The lines are probably cleavage lines, which are (probably)
natural, but it’s just waiting to finish the job and split. The only
difference between wax and fabrication is that fabricated prongs and
bezels are drawn so they have superior setting properties in general.
I’d probably try to set it in some sort of modified cushion setting.
One stategy: Make a sheet “bezel” as thick as you want that fits
around the stone as high as needed to encase it, solder a bearing
wire inside it at a height to accomodate the stone and cut the angle
to suit the pavilion (we call that the “belly” a lot). Then saw cut
four prongs out of the top edge and use those to set the stone. A
true bezel set is going to be risky at best. It’s a place to glue
down the stone before pushing the prongs down, too. You could also
make the bezel and solder prongs in various ways, too, but what I’m
suggesting is a bezel look with lighter prongs to hold the stone - if
the stone is encased in the bezel form, and it’s a pendant, you won’t
need that much metal to hold it down.

http://www.donivanandmaggiora.com


#5

Hi Zac,

Whether to cast or fabricate depends on your set-up. In my case I do
no casting except sometimes to get a suitable blank by sand casting,
then everything is fabricated. I think fabricating one-offs takes the
same time or less than casting. Carve the wax, or carve the metal?
When you have carved the metal you are there.

A pendant setting can be fabricated easily using a strip of metal
with the seat either cut into the metal, or by soldering a separate
seat inside the setting. This applies to either a full bezel or one
that is cut and scalloped into a claw setting. The sides of the
setting can be pierced or left solid. With deep stones there is a
large area to play with because the sides of the setting must be as
deep as the stone.

Deep stones in a pendant tend to roll and sit sideways unless
preventive measures are taken. One method is to make the base of the
setting at least as wide as, or wider than the top of the stone; ie
straight sides, or a reverse taper, or an extra rim at the bottom of
the setting to make it wider. Another method is to make the bale very
wide so that the chain is hard to twist - assuming a flexible
necklace is used.

Alastair