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Diamond cutting


#1

Could anyone list for me all the equipment required for diamond
cutting including an estimate of this equipment’s cost ?

Thanks a lot

Claude Marc-Aur=E8le

Lapilia
CP 255 Outremont Branch, Quebec, Canada, H2V 1L5
E-Mail : lapilia@vipxlnet.com
WebSite : http://www.vipxlnet.com/lapilia/accueila.htm
Gemstones from all around the world


#2

Claude do you want to buy new equiptment or used? I have a business
partner who has been cutting diamonds for 58 years I can ask him if
you would like I know he knows how what and who to talk to to set
you up. Vernon


#3

Before I became a jeweler, I was under the impression that diamonds
(and, presumably, other stones) were cut with chisels. I was
startled to discover that they are not really “cut” at all, but
ground and polished. I can recall a movie, as well as a car (tire?)
commercial that perpetuated this notion-- the commercial showed a
"diamond cutter" at work in the back seat of the smooth-riding car.

A Google search found no info suggesting that diamonds were ever
really shaped by cleaving in this way, so I am at a loss to explain
the misconception. This came up again a couple of nights ago, when I
told an aquaintance that I am learning stone cutting. He was under
the same mistaken impression, for pretty much the same reasons.

Does anybody know of any time in history when diamonds were actually
"cut", or is this just a complete fiction?

–Noel


#4
    Does anybody know of any time in history when diamonds were
actually "cut", or is this just a complete fiction? 

Indeed, diamonds are cleaved. This form of stock removal only works
in a few directions, particularly, parallel to the octahedral faces.
There is little diamond turned to dust in this way and it is very
quick. Other forms of stock removal are sawing and grinding.

You can try some cleaving yourself with salt, galena or calcite
crystals.

Some years ago, I cleaved a blue topaz through the girdle. That is
the very thickest direction to split a stone into two parts. Pretty
amazing,

really. The table, being the largest facet is oriented to be nearly
parallel to one of the cleavage planes because that is the easiest
way to polish it.

Bruce D. Holmgrain
http://www.goldwerx.com
@Red_Rodder
JA Certified Master Bench Jeweler / CAD/CAM Solutions


#5

Noel,

Your impression that diamonds were cut with “chisels” is correct. I
understand that much of the industry now uses lasers instead of the
traditional cleaver’s knife however. Cleaving is done in order to
separate the crystal into two or more pieces , remove flaws or to
open a window into the stone. This is also done by sawing.

Jerry in Kodiak


#6
 A Google search found no info suggesting that diamonds were ever
really shaped by cleaving in this way, so I am at a loss to
explain the misconception. This came up again a couple of nights
ago, when I told an aquaintance that I am learning stone cutting.
He was under the same mistaken impression, for pretty much the same
reasons. Does anybody know of any time in history when diamonds
were actually "cut", or is this just a complete fiction? 

Noel,

It is not, nor is it today, complete fiction. The problem is that
cleaving is not done to produce finished facets. Well, not today.
Some older rose cuts (flat backs) sometimes appear to have a simple
cleavage plane as the back surface. And some of the really tiny
things called chips (the term is usually incorrect. But not always),
sometimes appear to be just little diamond crystals that have been
split (cleaved) to produce one or two semi flat surfaces. Whether
that’s deliberate, or just as found, I don’t know. But in general,
cleaving is a process used for purposes similar to the way a slab
saw is used in general lapidary work.

Diamond has four directions (planes, if you wish to use the precise
term), along which it is not only at it’s hardest, but along with it
will also tend to separate. cleavage planes are known in other
stones. Topaz, for example, is extremely easy to break in one
particular direction, but only modestly brittle in the others. Mica,
the common mineral, is so cleavable you can separate it into thin
sheets. Not all minerals have cleavage planes. Some have none, and
many that do have them have only one. The direction of cleavage is
dependent on the crystal structure. You don’t get to choose…
Diamond, as it happens, has four such directions. (similar to
fluorite, a very soft mineral which is OFTEN shaped into decorative
rhombahedrons by simply cleaving the stuff and then polishing the
result.)

But back to diamond. The thing is, diamond varies in hardness
depending on the direction through the crystal. In some directions,
it’s softer than others. Diamonds can be facetted using diamond dust
as the abrasive because some percentage of the dust particles will be
presenting a hard enough direction to the stone being cut, to be able
to scratch/abrade it. Diamond cutters need to avoid, if possible,
placing facets parallel to the hardest directions (these are parallel
to the octahedral crystal surfaces), or grinding slows down
tremendously, as the grinding is then done by particles of the same
hardness as the surface being ground. Like sanding wood using
sawdust as the abrasive. Not efficient at all…

Anyway, in many cases, before a diamond crystal is cut/ground and
polished into a finished stone, the crystal needs to be separated
into several parts. Normally, each crystal yields more than one
stone. Now, the softest direction in the diamond crystal is parallel
to the cubic planes of the crystal, and this happens to be the plane
in which normal round brilliants will end up having their table
facet. Well shaped octahedrons are divided into two pieces, either
the same size or one larger than the other, each then being roughly
pyramids. Because this plane of separation is parallel to a cubic
plane in the crystal, it generally is done via a diamond saw. That’s
a thin metal disk with diamond dust at it’s edge, or fed to the edge,
as the abrasive. It was developed in the early 1900s, and is still
in use. Similar to standard lapidary saws.

However, with oddly or irregularly shaped crystals, it sometimes is
desired to divide a crystal in other directions. Some of them, to a
degree, can still be sawn. But if the desired saw cut is parallel to
an octahedral plane in the crystal, the saw has almost no effect.
This is when the longtime traditional process of cleaving comes in.
Another diamond is used to dig a carefully positioned groove on the
surface. A steel wedge is placed in the grove and carefully struck
with a small hammer. It’s risky. Done wrong, the crystal can
shatter, or fracture along the wrong plane. (this is why the
process made a good ad for a smooth riding car) Done right, it just
splits in half. Cleaving is regarded as rather an art form, perhaps
something of a lost art, as the cleaver must consider internal
condition of the stone as well as just the process, to predict how
and where he can do it without accident. One slip with the wedge of
hammer, or the wrong decision as to how and where to attempt to cleave
the stone, and one can destroy the whole thing. Note that the
wedge does not actually cut the way a chisel does. Instead, it puts
pressure on the sides of the grove, pushing them apart, splitting the
diamond the way an axe splits wood along the grain where with a good
hit, a log can sometimes be split in two with only a short penetration
of the axe, but it’s enough to force the wood fibers apart enough to
split the wood. Somewhat the same sort of thing with diamond. And
just like with wood where a knot in the wood can make it split in
something other than a clean flat plane, inclusions and flaws in a
diamond crystal can also disrupt the way the stone cleaves. Thus
the tension and risk. The cutter must hope not only that he’s
correctly analyzed the stone to choose the right places, but then has
to get the process itself, with the wedge and hammer, done just right
too. Some of the large famous diamonds got months of study before
decisions as to where and how to cleave or saw the roughs were made.

Before the invention of the diamond saw, cleaving was the only way
to carefully divide a diamond crystal into multiple pieces of rough
to produce more than one stone from a given rough crystal. One
common reason to do this, by the way, might be damaging inclusions
one would not want within a larger finished stone, or simply a stone
where cutting a single stone would result in much wasted material,
which if separated into a distinct piece of rough rather than just
ground off, can improve the yield. It is, of course, limited in
that only certain directions can be cleaved. With the advent of the
diamond saw, it wasn’t as commonly needed, but the two processes are
not duplicates. Cleaving works only along the four octahedral
directions/planes in the stone, while sawing works everywhere else,
but not along those directions. These days, we also have the recent
development of lasers capable of cutting crystals in half, or
profiles, or whatever, but then the laser cut removes a measurable
width of kerf (so does a saw), while cleaving removes less material,
if any. So even today, some stones need to be cleaved. But it
simply is not the process by which the final shape of the stone is
arrived at.

HTH
Peter Rowe


#7

Hi Noel,

Well the GG’s can probably explain this better but diamonds were
(and are?) cleaved. Technology has changed making a variety of
changes in the process easier but a good skilled cutter will still
yeild more from the rough material than a rookie and that’s the key.
How to cut and what to cut from each piece of rough. (ps, rd, mq,
em, etc) It is important to get the best $ yeild of quality and size.
This is of course refering to diamonds.

The old miners (fat and squarish) where cut to keep most of the
original octahedron intact and not loose weight. Cleaving allowed
the yeilding of two stones from an octahedron. One larger and one
smaller (table to table in the rough) yeilding stones that could be
polished more to their “ideal proportions”.

Lazer’s make things possible like the grooves needed for invisible
set diamonds. I’m sure there is a lot more that I don’t know or
remember from my GIA days but this should answer your question.

Mark


#8

Noel,

Cleaving is used to split a Diamond crystal along its atomic
structure and sawing is used to cut against it’s atomic structure.
This can be envisioned much like splitting a piece of wood along the
grain or sawing against the grain.

Cleaving and sawing are used on the raw crystal in order to separate
it into several pieces before fashioning.

What determines which process is used if at all is what will produce
the best return of the raw crystal.

Greg DeMark
Longmont, Colorado
email: greg@demarkjewelry.com
Website: www.demarkjewelry.com
Custom Jewelry - Handmade Jewelry - Antique Jewelry


#9

Thank you, Peter, for taking the time to write this wonderfully
clear explanation. It all makes perfect sense. I guess my Google
search didn’t use the right keywords, because, as I said, I found no
reference to any of this. I feel better now-- everything fits
together (like a cleaved [cloven?], not sawn, diamond),

–Noel


#10

Hi Noel,

Diamonds can be shaped and reduced in size by “cleaving”. Almost all
very large rough diamonds will be roughly shaped by cleaving. Regular
size rough will be processed by sawing. Today sawing will utilize
either a mechanical saw or a laser. Both methods of sawing will
result in some waste of the rough material. Cleaving, when done
properly, results in almost no wasted material.

Cleaving is done using a thin steel “iron”. The iron is struck a
solid blow and the rough diamond is split along a cleavage plane. The
diamond is examined to ascertain how the cleavage planes are
orientated. A groove is created on the surface which follows the
cleavage plane to prevent the iron from slipping. This is the process
which was done in the back seat of a moving car several years ago. I
think that was shown in a commercial done by Ford. All of the
subsequent steps in the polishing of a diamond are done by grinding.

Jim miller


#11

Of the four diamond cutting operations: cleaving, sawing, bruting,
faceting/polishing, you’re referring to cleaving, which is the
splitting of larger diamond crystals along cleavage planes (where
they are weakly bound). Misreading the cleavage or improperly
striking with the cleavage bar can crumble the crystal. Any mystique
surrounding this operation most likely derives from the mental
stresses surrounding cleaving huge and often famous raw diamonds.
Faceting and polishing is also called ‘cutting’ which is where
confusion sometimes arises, but these refer to grinding operations
on rotary laps.

Although ‘color’ can also be cleaved (I’ve done this easily with
topaz, which, like diamond, also has ‘perfect’ cleavage), it’s less
commonly done. This shouldn’t be confused with ‘cobbing’ colored gem
material, which is often done at mines to prepare for sale and
faceting/cabbing.


#12

My ego is forcing me to respond. If I am wrong, I am sure that
someone will let me know. I don’t have any reference works here so I
am doing this by memory.

The cleavage directions run along the octahedral faces. Anyone that
sets diamonds for a living has watched a few diamonds cleave from
the girdle past the culet. The Octahedron is sawed into two stones
of unequal size to optimize the diameter of one of the stones. The
table is parallel to the cubic faces.

Bruce D. Holmgrain
http://www.goldwerx.com
@Red_Rodder
JA Certified Master Bench Jeweler / CAD/CAM Solutions


#13
The table, being the largest facet is oriented to be nearly
parallel to one of the cleavage planes because that is the
easiest way to polish it. 

Actually Bruce, topaz is cut at least 15 degrees off the cleavage
plane, as it is hardest to polish parallel to the cleavage plane, as
pieces can break off and scratch the facet being polished.

Richard Hart


#14
   The old miners (fat and squarish) where cut to keep most of the
original octahedron intact and not loose weight.  Cleaving allowed
the yeilding of two stones from an octahedron. One larger and one
smaller (table to table in the rough) yeilding stones that could
be polished more to their "ideal proportions". 

A small correction, Mark.

The above cut is along a cubic crystal plane, not the octahedral
ones. The latter are the directions in which a diamond will cleave,
while the former are the softest directions, easiest to saw. One of
the key developments in diamond cut evolution was the development of
the diamond saw, which allowed exactly the above seperation to be
made. Prior to this, an octahedral crystal yielded one old mine or
old european cut stone. With the diamond saw, the crystal becomes two
pieces, and two stones. Suddenly, too, the economics of weight
retention mean that no longer is the high crown and small table the
best for yield, but rather, the shallow crown and wide table of the
"spread" stones. So in addition to giving us more ways to divide a
rough into multiple pieces, the saw also gave us spread and swindled
stones… Cleaving doesn’t follow the needed directions to do this
for uniform octahedral crystals. Mishapen ones, or those with flaws
that require the stone to be divided, may be cleaved, and the
cleavage planes that result may or may not be oriented near to the
table facet. Generally not exactly in the same plane, though, since
the cleavage plane is also the hardest direction in diamond, and
thus very difficult to polish.

cheers
Peter


#15
    commercial that perpetuated this notion-- the commercial
showed a "diamond cutter" at work in the back seat of the
smooth-riding car. 

That was a VW Bug commercial!

Isn’t that the first step, where you cleave the rough into the
smaller parts that are then cut and polished in the way you’re
familiar with.

There’s a story of one of the really big diamonds and the diamond
cutter studying it for months, finally deciding and then he cleaves
it, successfully, then faints. Don’t know if it’s true, but it’s a
good story.

Hopefully a lapidary will respond. I just know the part about the
commercial.

Elaine
Elaine Luther
Metalsmith, Certified PMC Instructor
http://www.CreativeTextureTools.com
Hard to Find Tools for Metal Clay


#16

Peter’s explanation is about as perfect as is possible in such a
short format, but I disagree mildly with one point. While the
octahedral is the cleavage plane, and the cubic is the sawing plane,
I believe the dodecahedral, or polishing plane, is the softest
direction, not the cubic. Still, the point is clear that diamonds
are cleaved (or cloven) for several purposes.

Also, laser cutting has been mentioned. That method does cause far
more waste than cleaving or sawing, is quite expensive, and is
usually reserved for fancy shapes, such as stars, hearts, etc. These
fancy shapes are typically cut from diamond rough that is triangular
in shape (referred to as “macles”). Macles are rough diamonds that
were formed in the earth for a time, then a geologic event caused a
change in the direction of the crystal’s growth. So, looking
sideways at the triangle, the top half grew in one direction, and
the bottom grew in another. Now that you now about how hard diamond
is in it’s different crystal planes, you’ll see that a macle can be
quite a challenge to cut.

Instead of cleaving or sawing, a laser simply burns away material,
but it can’t just burn straight through. It must start at the top
with a wide swath, with narrower successive cuts as it burns through
(picture a “V” cut). Once the outline of the macle has been formed,
it is then a matter of following polishing directions to block in,
then brillianteer the facets.

Diamond crystal structure is a fascinating subject. Once understood,
it explains why you can use it to shape a piece of jade into a
hammer, then use the jade hammer to smash a diamond to pieces.

James in SoFl


#17

The table, being the largest facet is oriented to be nearly
parallel to one of the cleavage planes because that is the
easiest way to polish it.

Actually Bruce, topaz is cut at least 15 degrees off the cleavage
plane, as it is hardest to polish parallel to the cleavage plane, as
pieces can break off and scratch the facet being polished. 

The cleavage plane of the cited stone was close to 1 degree of the
table. I base that in the fact that the break was entirely within the
girdle. Not parallel, but close. Some time after doing this I read
that the cleavage plane should be close to the table. I have no idea
where I read that.

This almost validates what you are saying.

According to Vargas, "The cleavage plane of topaz must be carefully
oriented. It should not be less than 10 degrees away from the table,
and should not be close to parallel to any other fact.

According to Sinkankas "When preforming gemstones with good
cleavages the easiest way to be sure that the cleavage planes do no
coincide with with any facet is to place the cleavage planes
vertically in the stone or tilted five to ten degrees from the table
facet.

Bruce D. Holmgrain
http://www.goldwerx.com
@Red_Rodder
JA Certified Master Bench Jeweler / CAD/CAM Solutions


#18
  Anyone that sets diamonds for a living has watched a few
diamonds cleave from the girdle past the culet. 

Now that you mention it, though I don’t set diamonds much at all–
I bought a batch of chipped diamonds to use in the “teabag” of the
piece “Just My Cup of Tea” that I posted here about, a while back,
and many of them were missing chunks that extended from the girdle
to the culet in a way that mystified me. Now it makes sense! Always
nice to have a mystery resolved.

–Noel


#19
 Peter's explanation is about as perfect as is possible in such a
short format, but I disagree mildly with one point. While the
octahedral is the cleavage plane, and the cubic is the sawing
plane, I believe the dodecahedral, or polishing plane, is the
softest direction, not the cubic. 

thanks for the compliment James. I believe you are correct in your
correction. I won’t even try to say i was simplifying. I just forgot
that bit. Thanks for the clarification.

Peter


#20

Why not make a visit to Antwerp? We have the new diamond museum
where they’ll explain everything and I’ll show you around the
diamond quarter. In the middle of town is also a statue of the
person who brought the diamond industry to Antwerp.

Greetings from Antwerp,
Linda