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Frustrated with final designs


#1

So often I expect to be more pleased with my designs than I am. When
I hang a pendant around my neck, the stones don’t catch the light as
well as they do lying flat on my workdesk. I just made one today
with an Almandine Garnet that looks very dark, almost black when
worn. Any tips on designing with the stones so they catch the light
when worn? I don’t want to put a hole behind them. I tried that with
amethyst and it made no difference. I have quit using amethyst
cabochons for this reason. Is it necessary to always use lighter
colored stones?

Janie Sue Ellington


#2

If you don’t set stones with an open back you can’t hope to get the
full play of light from them. Stones are cut so that both the light
entering through the top and back facets are refracted through the
table.

Tony Konrath
Gold and Stone
http://www.goldandstone.com

End of forwarded message


#3

Try puting polished metal directly behind the cabachons, you can
vary the effect by color/curvature of the metal. Mark Clodius


#4

Dear Janie, Light reflection through stones is the art of the
lapidary. Well cut stones enhance the color of the stone, not blacken
it. Poorly cut stones have windows through them so you can see right
through or don’t concentrate the light reflecting off them toward
your eye. Cabs need to have shiny backing material behind them such
as white gold or aluminum foil so light does not just pass through
them but reflects off the backing material to your eye.

Sam Patania, Tucson


#5

Maybe the hole in the rear wasn’t large enough. The more transparent
the stone the more you will see behind it. So if you have allot of
metal that’s what you’ll see.

Also the depth of the setting would also effect the reflections as
well.

That’s my 2 cents I don’t set stones yet :smiley: Guy…


#6

Hello Sue,

A very old trick is to foil the back of the stone. In the early days
gold foil and silver foil was used. Today you can find nice metallic
foils (from gift wrappings) Try at the back of the stone a piece of
silver foil, and the stone will give a brighter reflection. Also if
you have white stones, try a piece of blue metallic foil, you get a
blue moonstone effect.

greetings
Martin Niemeijer.


#7

Tony,

The person you were responding to was setting cabs, therefore no
facets to reflect light, and when a stone is faceted with correct
pavillion angles, you can set it in a tube setting that is closed in
the back and get just as much refraction as from an open back
setting.

Many people have a mistaken belief that light entering from the back
will make a difference in how the stone will look. Not true. The
point of the pavillion facets is to return light back from where the
source is, therefore it seems that light entering from the back
would reflect off the table and crown facets back to the source
behind the stone, the principle that works on the top should work the
same on the bottom.

Richard in Denver,G.G


#8

Hi Janie,

The answer is contained in your question. You wrote:

   When I hang a pendant around my neck, the stones don't catch the
light as well as they do lying flat on my workdesk. 

You’re right! They don’t! :slight_smile:

The optical properties of a cabochon are very different from those
of a faceted stone. When you bezel set a translucent cab, you
drastically reduce the amount of light which enters through the side
of the stone. That’s why your Almandine appears darker in a setting
than it does on your workbench.

   Any tips on designing with the stones so they catch the light
when worn? I don't want to put a hole behind them. I tried that
with amethyst and it made no difference. 

One option is to use prongs (as few as possible) instead of a bezel.
(Yes, I know that involves more work! ) A prong setting will
allow light to enter your cab from the side. Side-lighting is an
important consideration when setting translucent or transparent
cabochons; whereas it’s nearly meaningless when setting faceted
stones. If your design requires a bezel setting, try to cover as
little of the stone as possible.

Another good option is to purchase cabs with polished backs.
(Polishing the back of a translucent cab increases the quantity of
light which is reflected up toward the dome - thus making the cab
appear brighter. Cutting a convex surface on the back of a cab will
also improve light return; though it makes the cab considerably more
difficult to set.)

   I have quit using amethyst cabochons for this reason. Is it
necessary to always use lighter colored stones? 

Color saturation won’t cause the problem you described, unless the
coloring agent in the stone has rendered it nearly opaque. :slight_smile:

I hope this is of some use to you, Janie!

Best Regards,
Pete

Peter B. Steiner
Buffalo, NY, USA


#9

Actually, I tend to differ on the theory that a ring with an open
back will shed more light on the stone. That works if the ring is not
on your finger. However, if the ring is on your finger, light cannot
get to it from the backside… so if you really want to have light
on the stone from at least 2 directions, have an open back and have
the sides open as well… now you will get light on the stone when
it is on your finger from the openings on the side. Daniel Grandi


#10

I used to use aluminum foil as a backing for translucent cabs, but
have gotten even better results with Mylar foil. It doesn’t crease,
and it comes in gold, silver, bronze and other metallic colors you
can use to enhance the stone in its setting… I picked up several
assorted sheets in a gift-wrap place , and have found its reflective
quality to be superior . Dee


#11

If the back is open and it’s a ring how is it that light comes
through the back when it is worn?


#12

Hi Gang,

That works if the ring is not on your finger. However, if the ring
is on your finger, light cannot get to it from the backside... so
if you really want to have light on the stone from at least 2
directions, have an open back and have the sides open as well.

Actually whether light striking a faceted stone from multiple angles
does any good depends on how well the stone is cut. If the stone is
well cut (pavilion angle above the critical angle & crown facets cut
to enhance light capture), having the pavilion exposed to light
really doesn’t buy very much, if anything.

The light & scintillation that is seen when looking at/into the
stone from the crown is reflected light that entered the stone
through the crown. It gets bounced around the inside of the stone,
reflecting off the various facets until it exits the crown.

If you look at a stone that’s been cut without regard for the
critical angle, the stone will typically ‘window’, if you look
through the table, you can look right out the pavilion (bottom). A
stone cut like this will be dead looking.

The critical angle varies for different stone species. The critical
angle is dependent on the refractive index (R.I.) of the material
the stone is cut from.

Dave


#13
Any tips on designing with the stones so they catch the light when
worn? 

Is it possible for you to wax up the stones on a glass easel much as
a stained glass artist would to check the flow of light through an
unbuilt window? We use a combination of beeswax and rosin that is
rolled into balls and pushed onto corners of the glass onto the
glass easel. Sometimes the glass remains that way on the easel for
days while we review colors under changing light, effect of
painting, etc. Might work with gems also… you could even tape
various colors of paper behind the stones to see the effect clothing
might have. Just a thought… not necessarily good.

Good luck,

Dani Greer
Greer Studios


#14
I used to use aluminum foil as a backing for translucent cabs,
but  have gotten even better results with Mylar foil. It
doesn't crease, 

To all, The use of aluminum foil or other non-precious metal
backings behind stones should be done only with heat-sensitive
stones, or not at all. I recently had to rebuild a piece of
jewelry from Romania which another jeweler had inadvertantly ruined.
It was a cross set with antique rose cut diamonds mounted in buttercup
style crowns with inverted domes behind each, lined with aluminum
foil for the added brilliance it gave the stones. Not knowing the
alumium was there, the other jeweler attempted to retip the prongs of
the diamonds and alloyed the aluminum and gold with diasterous
results…melt-down of 2 crowns,and dicoloration of three others
where the alloying went through to exposed surfaces. (The resulting
alloy was very hard and brittle and could not be removed without
removing entire crowns.) Each crown was fused to six beads underneath
it and they where finally fused to a pierced out back plate following
the contours of the crowns and the cross shape; much of which needed
to be removed due to aluminum contamination. The entire restoration
took about seven hours and was quite costly to the customer.
Rather than using aluminum for the reflectors I rolled out .999
platinum to foil thickness as a very shiny and non-oxidizing
replacement. The Platinum price added minimumally to the overall
cost of the repair ( about seven to ten dollars U.S., if I recall)
and made a more durable product not likely to have some poor jeweler
suffer the same dilema as the last one did. Paul Reilly
Colorado Springs, Colorado


#15

I’ll admit to not understanding that we were discussing cabs but…

It’s my understanding that a well cut diamond will refract the light
entering the back of the stone through the table facets and that
correct proportioning in other stones will allow this as well.

In other words, you think I’ve got it wrong, I think you’ve got it
wrong! (I’d put one of those smiley faces in here but I hate them!)

Tony Konrath
Gold and Stone
www.goldandstone.com
tony@goldandstone.com


#16
    So often I expect to be more pleased with my designs than I am.
When I hang a pendant around my neck, the stones don't catch the
light as well as they do lying flat on my workdesk. 

Welcome to the fine art of stone orientation! In coming up with a
design, you need to consider how a stone looks when in it’s worn
position. Especially stones that exhibit light phenomena. ( star
stones, eye stones, chatoyant stones, opals,etc.) Play around with a
stone in a vertical position, rotate to find it’s best look, and
design for that position.

just made one today with an Almandine Garnet that looks very dark,
almost black when worn. Any tips on designing with the stones so
they catch the light when worn? 

Almandine can be very dark especially in large sizes. And if not cut
with the utmost care, it can be worse.

   I don't want to put a hole behind them. I tried that with
amethyst and it made no difference. I have quit using amethyst
cabochons for this reason. Is it necessary to always use lighter
colored stones? 

Lighter color may not be the answer, they can look washed out. Better
transparency is! As other posters have stated a very shiney setting
can certainly liven up a stone. (cabachon) A hole behind a faceted
stone will not save a poor cut. (nothing can, IMHO) If any of this
strikes a chord, please feel free to contact me off list. Later,
Mark

Mark Thomas Ruby
SunSpirit Designs
Loveland, CO
970 669-7075


#17

Tony, I think you may be ( no, you are) wrong. All the light enters
through the table and if cut correctly the light does not leak out
the pavillion, but bounces back to the viewers eye providing the
scintillation that one sees in a well cut stone? KPK


#18

All, Been watchin this thread for a week now and yet no one has given
the right answer (at least I haven’t noticed it…apologize if I
missed it) for why there is a hole under diamonds, other faceted
stones and even many cabs when set.

The hole is there for three reasons in my opinion. 1) to provide a
way to clean the stone all over…including the culet, 2) to provide
relief for the culet…so it will not rest on the metal and thus, if
bumped etc, it cannot be broken and 3) the stone is set up above the
bearing and above a bottom hole so its beauty (i.e. color) can be
seen.

Re setting cabbed stones in an open back…there has to be a reason
to set it that way. Either the back has its own beauty that should be
shown, the setter wants to conserve weight when setting a large stone
or a smaller stone in a heavy piece, the stone needs an open back to
provide some translucency to display design (i.e. dendritic or iris
agate, etc) or perhaps the stone is beautifully cut (cabbed or
faceted) but the color is a bit dark. In the latter case there is no
need to try to provide openings for brilliancy or scintilation as
there will be none. Such stones are cut purely for their intrinsic
color and sometimes an opening will help the color but more often
than not it will not. I feel foiling such a stone is a waste of time
and effort and a good setting. I simply would not set it, unless
there is some other point of beauty one is trying to enhance. Even
then, foiling is a bad answer. KP is correct here… all the light
seen coming from a faceted stone (i.e. brilliance) originally entered
through the table. In the case of many colored stones (either faceted
or cabed) there is little or no light return as it is all absorbed in
the stone, hence it will be quite dark. Pyrope garnets are notorious
for this as are tourmaline and even many sapphires, etc. My opinion.

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut1


#19
  Even then, foiling is a bad answer. 

In this context, you may be right but there is an entirely different
reason why I foil cabs. When I lay out stones for a design, I do it
on a white pad so that the hot pink of a tourmaline matches the hot
pink in a, for instance, piece of cobalto calcite drusy. If I then
set my tourmaline in a gold bezel, without backing it, it will become
a peach-colored tourmaline. Similarly, transparent blue-colored
stones turn green when set over gold. If I leave the backs open, on
the other hand, and the piece is worn over black, the transparent
stone will grey out. Since I’m the designer and want to control the
color of my pieces as much as possible, I foil the backs.

Beth


#20

Dear Don, I cannot disagree with anything you’ve said–what a
thoughtful answer. But there’s one other very obvious reason for the
hole in the back–to make it easy to get the damned thing OUT
whenever you may need to! Otherwise you’ve got to use gravers, etc,
and destroy the bezel usually. This way, often just a wooden or
plastic dowel can get it the stone out quickly and easily.

Gary Strickland, GJG
PS: Thanks for the great black coral you sent last year.