Soldering Works!

"William Black"

Sorry, it's complicated, 'scorper' is the generic name for a range of
specialised gravers.used in stone setting.

They are used to cut the silver away so that the stone sits on a
'shoulder'
and also to remove surplus metal at teh top of the setting so as to allow
it
to be bent over the stone...........

I guess the problem is that I do not have any idea of the your starting
point.

My experience has been with "easy set" type of stuff where the stone is
plopped into the setting and the prongs are bent to keep it from falling
out. Not even bottle rocket science.

Where does all this micro machining fit in?

js


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On , in Ìô Jack Schmidling wrote:


I guess the problem is that I do not have any idea of the your starting
point.


Properly made settings are the starting point. Then you have to fit the stone to
it, so it correctly contact the prongs evenly, while allowing you to then,
without breaking the stone set the metal over the stone that will hold it.
Commonly, one does this cutting and fittinf of the prongs with various hand
tools, such as jewelers saws, needle files, rotary burs in a flex shaft or other
hand held motorized setup, or engraving tools. The later, also called gravers,
burins, or scorpers, depening on where you're from, and which types of tool shape
one is talking about, are basically just small hand driven, very sharp, chisels
with which one can shave off very precise amounts of metal.

My experience has been with "easy set" type of stuff where the stone is
plopped into the setting and the prongs are bent to keep it from falling
out. Not even bottle rocket science.

You're right. But also not very good stone setting. The easy set type things
are not all that well fitted to the stones as is. good enough to seem OK to an
ameteur, or for cheap jewelery, but the poorer fit means the stones are less
secure, more easily loosened from the mountings. Also, to minimize the
percentage of stones that will be chipped and broken in using the easy sets,
they're made rather thinner than a pro would usually do, and often of softer
alloys, so they bend easily. Trouble with that is then they're just as easy to
unbend if one puts some stress on the mounting during wear. And because the
notches in the prongs are "generic" rather than fitted to the individual
measurements and slight variances of the stone, the possibility of a prong not
quite fitting exactly is much higher. That misfit greatly increases the chance
of chipping or breaking a stone.

But the process is essentially the same as you've seen. just taken to a whole
new level. As well, properly done, stone setting needs to address such aspects
as the prongs not catching on fabrics, a look for the finished stone that well
balances the mounting (something that can differ from stone to stone), durability
of the finished setting, long term security, and of course, managing to get it
set without breaking it. The latter is of no great concern if one is selecting
stones from the five dollar bin of synthetics for cheap birthstone jewelry. it
becomes of major concern when one is setting better stones, stones that already
belong to a customer, or stones one is selling for enough money that replacing it
if broken would be a major expense.


Where does all this micro machining fit in?

not really machining, just usually hand fitting. The idea is that the notches
need to properly fit the girdle of the stone all the way around, each prong in
the same degree of contact and pressure on the stone. With custome precision cut
stones, this is not that hard. But most commercially cut stones vary more, with
different girdle heights, often girdles that are wavey or differ in height or
thickness. And most good gems are not a precisely calibrated size and shape
either.

yes, it sounds simple. And in essence, the concepts are not complex. but the
practice of stone setting takes exactly that. Practice. To get good at it takes
a LOT of practice.

Note too, that stone setting is a lot more than just notching and bending prong
tips. Bezels may be thin rims, easily burnished over, or may be thicker metal
that needs a punch and hammer to drive down over the stone. or it may involved
precisely fitted tapered holes in a piece of metal, and then you use a graver to
push bits of metal from the surrounding field of metal up and slightly over the
stone, forming small hemispherical bead shapes holding in the stones. Again, it
sounds simple. Doing it well is another matter entirely. And if doing one is
not so bad, getting a hundred small diamonds set into a ring this way, all set
identically so the appearance of all is the same, with all stones set properly
level to each other, and almost touching each other... and doing it in, say, a
high nickle 18K white gold, which is a hard, springy, sometimes brittle metal
that makes mild steel look like clay to work with... And remembering that with
this style of setting, there's often little or no extra metal at all to work
with. Slip and cut off a bit you needed, and you're in deep do-do...

yeah, maybe not rocket science. this can be a lot more work than just lighting
a rocket...

Peter

William Black wrote:
"Jack Schmidling" wrote in message
...

"William Black"


Usually the mount for a conventional round stone is a conic section made

by

forming it with a tool set in a die with the silver tube between them,

you

then belt it with a hammer and anneal....

Roger on that but what I am trying to do in minimize the height profile so
they don't look like pretty warts. I have drilled holes and used cut down
commercial heads and used a counter sink to form a conic hole but find

that

just selecting the right size hole puts the stone at the proper level.

I was under the impression that the stone could not touch anything much
without destroying the optics but I guess as long and it's not filled with
glue or some such thing it does not matter.


True, and hole right through the piece for the light to get through helps

Correction please, a properly cut stone needs no light to enter it from
behind or from the side. A few facet edges resting against a metal edge
or 2 will not affect it's optical performance though most medium to low
refractive index gems WOULD be compromised to varying degrees by having
adhesives applied to the pavilion.

Carl
1 Lucky Texan


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"Carl 1 Lucky Texan"

Correction please, a properly cut stone needs no light to enter it from
behind or from the side. A few facet edges resting against a metal edge
or 2 will not affect it's optical performance though most medium to low
refractive index gems WOULD be compromised to varying degrees by having
adhesives applied to the pavilion....

That seems a bit of an understatement. I epoxied a nice CZ into a ring at
the insistance of a friend and it totally destroyed it. I think the reason
hard metal has little effect is that contact is minimal and only where
facets meet. Adhesives cover everything and become visible through a
perfectly cut stone because of the refractive index of the epoxy vs air.
The RI of the stone makes no difference unless it is the same as epoxy.

js


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On , in Ìô Jack Schmidling wrote:

That seems a bit of an understatement. I epoxied a nice CZ into a ring at
the insistance of a friend and it totally destroyed it. I think the reason
hard metal has little effect is that contact is minimal and only where
facets meet. Adhesives cover everything and become visible through a
perfectly cut stone because of the refractive index of the epoxy vs air.
The RI of the stone makes no difference unless it is the same as epoxy.

the key is that the proper reflection of light from the pavilion of the stone
depends on maintaining the difference in the refractive index of the stone, with
what is optically in contact with the stone. Normally, this is air, and there is
then enough of a difference in refractive index, that light is able to properly
reflect from the paviolion facets. When any material with a refractive index
higher than air, is in contact with the pavilion of the stone, the angle at which
light mist strike a facet in order to internally reflect, rather than just
passing out of the stone, is much shallower, greatly decreasing the angles at
which light will reflect. So then light just passes out of the stone, and the
stone appears dead, and you see through it, instead of seeing reflected light..
Glue forms an optical contact with the stone. So does stuff like dirt, oils, etc
On the other hand, the metal of a mounting generally cannot "wet" the surface.
Even when it appears in contact with the stone, it's not intimate enough contact
to exclude the tiny film of air, and then the air is what is in optical contact
with the stone, and the stone appears all right. In a few cases, especially with
hard stones like diamond, and soft malleable metal like platinum, I've seen cases
where some portion of a mounting was pressed hard enough to a back facet to
exclude the air, and that spot, even with diamond, will appear as a dark shadow.
Not as bad, though, as the glue, etc, since when metal is pressed hard to a
diamond surface, if it's in optical contact, then what is in optical contact with
the stone is, after all, highly reflective metal. A mirror. So then IT reflects
the light back, and not all is lost. it just looks like a different spot. That
principal is why the cheap glass rhinestones known as "foilbacks" work so well.
Though they're just glass, they're coated on the back with an actual mirrored
coating, so light reflects from a back coating that's actually metalic, and
perfectly reflective, not depending on refractive index at all.

Peter