LAPIDARY ARTS and FACETERS DIGEST
Issue No. 178 - Thursday July 31, 2003
Moderated by: Thurmond Moore III
Committed to carrying on the fine works of
Hale Sweeny and Jerry Dewbre
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Index to Today's Digest
01 NEW: Cutting oil
02 NEW: Chatoyant Beryl
03 RE: Materials, Methods. (Raytech Handpiece materials)
04 NEW: Larimar
05 RE: Hand pieces
06 NEW: Locating C-axis on sapphire
Subject: Cutting oil
Date: Wed, 30 Jul 2003 16:19:40 -0400
From: "roy meade" <email@example.com>
Lately there had been talk on the internet and in Lap[idary Journal
about the use of one of the new transformer oils (i.e.Shell's Diala AX)
in rock saws. Formerly the use of transformer oil as a saw coolant was a
no-no due to the PCB's. But this new oil from Shell has no PCB's as is
the case with all the new transformer oils, so I've been led to believe.
The advantage I understand to the use of these light oils is that they
are cleaner, smell sweeter, etc. than the Al-mag type oils currently
used. Does anyone have any thing to add to this? Also where can us
simple rockhounds get less than 55 gallon barrels of the stuff?.
Subject: Chatoyant Beryl
Date: Wed, 30 Jul 2003 17:41:55 -0400
From: "Derek" <firstname.lastname@example.org>
I asked a similar question before but let me extend it. How many people
have experience with chatoyant Beryl, ie. High end gem quality catseye
aquamarine. Does anyone know of sources of this material in the US? I
have some a someone who might be interested in collecting. Also does
anyone have any chatoyant good color morganite who might be willing to
trade for blue or green?
Subject: Materials, Methods.
Date: Wed, 30 Jul 2003 21:41:47 -0400
To: email@example.com (LapidaryArtsDigest)
From: "Jonathan L. Rolfe" <firstname.lastname@example.org>
At 01:25 PM 7/30/2003 -0500, you wrote:
> OR (watch out Jon!) Gearloose could perhaps offer kits or
>hanpieces for you RS users. maybe you should email him?
I am unfamiliar with handpiece machines. Remember, until the Web, I never
SAW a commercial faceting machine. So on my own, I was building mast types
for myself because it seemed an intuitively obvious way of doing it. While
I see the advantage of being able to pick up the entire assembly to
leisurely and comfortably examine the stone, having a height adjustment
affect a vertically moving platen that must remain square to the lap
violates my personal "Keep it simple" philosophy. That said, people have
built beautiful platen type machines, such as David DeLisle's machine at
As to the complaints of aluminum wearing when the anodizing or paint wears
off, that is a natural consequence of the material. My first machine was
aluminum. Hands and fingers covered with polish and rock dust always wore
certain points to a jewel-like finish (With the production of Black Stuff).
One person sent me an old flyer from long ago for a "Golden Beauty"
faceting machine made of brass. Personally, I HATE polishing brass,
figuratively, or literally, but the marketing arguments advanced were that
it wore to a beautiful golden color, and the beauty was all the way through.
Not to demean someone's craftsmanship, but my attitude about buying a
machine for its material rather than performance or design seems silly.
Sillier still is that Type 303 Stainless Steel is as easily machined as
brass, costs less, and does not tarnish, is harder and wears better, and
IMO, LOOKS better- A surgical instrument, rather than Liberace's
candelabra. But that's just me. For the absolute ultimate, there is THE
answer: 6- 4 Titanium. Stiffer, lighter, and miserable enough to machine
for even the most dedicated masochist.
My first prototype RevX was built from it.
Now that the XS2 has been tested on dozens of stones, I may freeze the
design...I actually have generated some formal drawings...and I just
_MIGHT_ make it in Titanium. For me, as a gift to myself. No one, not
even NASA, could afford it were I to become twisted and sick enough to make
more than one.
Date: Wed, 30 Jul 2003 22:23:38 -0400
From: "Glenn Warr" <email@example.com>
I'm new to the list. I have been cabbing as a hobby for a little over ten years
now. I have a question concerning, what I have found to be a very frustrating
stone, larimar. Is there some secret in cutting this material? Everytime I get
a good cab started a chunk pops out of the face. At first I thought I just had
some bad rough, but I have tried enough different sources now that I am
wondering. Any secrets, or am I just giving up to soon? Thanks.
Glenn in Connecticut.
Subject: Hand pieces
Date: Thu, 31 Jul 2003 15:26:35 +0930
From: "aurimas" <firstname.lastname@example.org>
G'Day Thurmond and list
I use an Imahashi , but have not heard of platform type units being made
in Australia. However there are some clones made in Sri Lanka and used
by the large commercial cutters. I made contact with one of the cutters
over there and got a 96 index wheel at under 50% of the Japanese price.
Now I am a very happy chappy with a 64 and 96 wheels as well as several
If you are interested I could contact Sri Lanka and get the good oil on
Aurimas in Adelaide ,where the nights are the 3 dog type.
Subject: Locating C-axis on sapphire
Date: Thu, 31 Jul 2003 17:13:48 +0100
I was just going through my old posts and I noticed that someone had posted a
message asking how to identify the C-axis on sapphire. I don't think that anyone
has answered this yet, so here goes:
These two methods do not require any special equipment:
1) It is often possible to identify the orientation of the c-axis by carefully
examining the shape of your stone. Obviously, this won't be possible if you have
an alluvial pebble which has become completely smooth and rounded. But if your
stone still has crystal faces (or traces of crystal faces) visible on its
surface, that is the easiest way. You can consult any mineralogy textbook for
pictures of the characteristic shapes of sapphire crystals. Striations and
surface markings can also be useful.
2) It is often possible to identify the approximate orientation of the c-axis by
carefully examining the colour of your stone. Sapphires almost always exhibit
dichroism (the stone appears to be slightly different colours, depending which
direction you look at it). For example, in a sapphire, often you will find that
the c-axis is blue, whereas at 90 degrees to the c-axis the colour will be
greenish-blue. However, in many sapphires the dichroism is quite subtle, so this
method may be difficult with the naked eye. It's a lot easier with tourmaline,
where the dichroism is often quite obvious. If you can immerse the stone (in
water or some kind of high-RI fluid like oil or refractol), it makes things
easier, because this cuts down on confusing reflections.
The following methods require some basic gemmology equipment:
3) With a loupe or microscope: it is often possible to identify the orientation
of the c-axis by carefully examining inclusions and internal features within the
stone. For example, "Negative crystals" (sapphire-crystal-shaped cavities)
within the sapphire will be aligned in the same direction as the crystal itself,
and rutile "silk" needles can point in three different directions, but they will
all be arranged in flat planes at 90 degrees to the c-axis. However, you need to
bear in mind that (a) boehmite needles look fairly similar to rutile needles, and
these do NOT lie in the 90 degree plane to the c-axis, and (b) some crystal
inclusions may be oriented completely at random (e.g. if they were just trapped
inside the crystal as it was growing). So it helps to have a book on corundum
inclusions! In sapphire, colour banding is also a good clue to crystal
4) With a dichroscope: use a polarising dichroscope to look at the colour in a
similar way as method (2) above. The difference is that the dichroscope displays
the two pleochroic colours separately, side-by-side, so it is much easier to see
the difference between them. You need a diffuse, non-polarised light source,
your sapphire, your dichroscope and your eye in a STRAIGHT LINE (i.e. you are
looking straight through the dichroscope at the sapphire, which is being backlit
by the non-polarised light source). Now imagine that the straight line is an
imaginary piece of string, and that the sapphire is an imaginary bead that is
strung on that piece of string. Rotate the sapphire "bead" around the "string".
If you can see two colours through the polariscope, the imaginary "drill hole"
through your sapphire "bead" is NOT parallel to the c-axis. So "drill" another
imaginary hole through the sapphire in a different direction and perform the
procedure again. Eventually, you will find an orientation where you only see one
of the dichroic colours through both halves of the dichroscope viewing window,
even when you rotate the sapphire through a full turn around the string. When
this happens, you know that your imaginary drill hole is exactly parallel to the
c-axis. Again, this method can be difficult if the dichroism is weak.
Reflections can also confuse the issue (in which case, try immersing the stone).
5) With a polariscope: set up the polariscope with the filters in the crossed
position. Place your sapphire between the filters. Look at the sapphire through
the polariscope (again, imagine that there is an imaginary string that goes from
your eye, straight down through the upper polariscope filter, through the
sapphire, through the lower polariscope filter, to the light source). Rotate
your sapphire "bead" around the "string" as before. If the imaginary "drill
hole" through your sapphire "bead" is NOT parallel to the c-axis, the sapphire
will flash bright and dark alternately every 90 degrees as you rotate it around.
So "drill" another imaginary hole through the sapphire in a different direction
and perform the procedure again. Eventually, you will find an orientation where
the sapphire remains dark throughout a full 360 degree turn. When this happens,
you know that your imaginary drill hole is exactly parallel to the c-axis.
Again, reflections can confuse the issue (in which case, try immersing the
The following method only works if the surface of your stone is nice and
transparent (i.e. it normally only works on a faceted or cabbed gem rather than a
piece of rough with an unpolished surface). However, it might work on a rough
stone if you smeared it with oil to make the surface more transparent.
6) With a polariscope and conoscope: set up the polariscope with the filters in
the crossed position. Place your sapphire between the filters, and put the
conoscope between the sapphire and the upper filter. The conoscope ball should
be almost touching the sapphire. Look at the sapphire through the polariscope
(again, imagine that there is an imaginary string that goes from your eye,
straight down through the upper polariscope filter, through the ball of the
conoscope, through the sapphire, through the lower polariscope filter, to the
light source). Rotate your sapphire in all directions until you see the uniaxial
conoscope interference figure, which looks like a series of rainbow circles with
a cross through it (look in a gemmology book or on the internet, because it's
difficult to describe!). When the circles and the cross are perfectly centred,
that means that you are looking straight down the C-axis.
N.B. I was told that the traditional "belly-cut" method helps to isolate the
c-axis colour in a sapphire: align the table so that it is at exactly 90 degrees
to the c-axis, and then cut a fat pavilion with steep sides and a fairly shallow
tier of culet facets. Apparently, this helps to minimise the amount of light
that travels across the stone, thereby maximising the c-axis colour.
RESOURCES FOR LAPIDARIES:
PERSONALS: (General Lapidary and Faceting)
Lurking is fine, but participation is better for learning !
Post something from your experiences in gemcutting today!
TODAY'S FUNNY ~
The sun was bright on a beautiful spring day. A young bull and a big old
bull were walking along the country lane with the sweet aroma of
honeysuckle filling the air. Raising their heads as they were sniffing
the air, they noticed up a hill under a spreading oak tree a herd of
cows resting in the shade.
The young bull excitedly said to the big old bull, "Hey! Let's jump over
the fence, run up the hill and make love to one of them cows!"
"Nope!" replied the big old bull, "Let's climb over the fence, walk up
the hill and make love to all of them cows! "
Submitted by: ~ Doug Smith
REFLECTIONS AND TIDBITS:
"It's kind of fun to do the impossible."
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