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LAPIDARY ARTS and FACETERS DIGEST
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Issue No. 254 - Monday, December 08, 2003
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Moderated by: Thurmond Moore III
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Committed to carrying on the fine works of
Hale Sweeny and Jerry Dewbre
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POST TO EITHER LINK BELOW:
lapidary@caprock-spur.com
faceters@caprock-spur.com
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VISIT OUR WEBSITE TODAY
http://www.gemcutters.org
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Hi All, 

Remember the membership decides the Digest frequency
by posting volume.

Get those 10 post in for tomorrow.

Thurmond

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Index to Today's Digest

01  NEW: Briolette cutting instructions wanted
02  NEW: Scissors in Quartz converted to CZ
03  RE: RI and Tangent Ratio Conversion
04  RE: Tangent ratio
05  RE: Tangent ratio
06  NEW: Good article on the world's largest Imperial Topaz Mine
07  NEW: Silent Faceters
08  RE: Tangent Ratio
09  RE: Tidbits and Reflections
10  NEW: Merry Christmas (off topic)

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Message:01

Subject: Briolette cutting instructions
Date: Fri, 5 Dec 2003 07:40:05 -0800
To: <faceters@caprock-spur.com>
From: "Frank Norman" <klamathon@snowcrest.net>

I seek cutting instructions for briolettes, preferably for gemcad.  Any
advice, or the location of cutting instructions, such as books, or web
sites would be appreciated.

Thanks, Frank Norman
Email  klamathon@snowcrest.net

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Message:02

Subject: Scissors in Quartz converted to CZ
Date: Fri, 5 Dec 2003 21:47:05 -0800
To: lapidary@caprock-spur.com
From: Dennis.Anderson@djanderson.net

Charles wrote:

From: "Charles Rudokas" <cprgolf@go-concepts.com>

Well I'm trying to do another CZ emerald and the only design I can find

I like is a Scissors in quarts. The quarts has an R.I. of 1.54, critical

angles 42/43 and the CZ has 2.2, critical angles 35/41.
>>>>>>>>>

Charles:

Looking at this design, I say don't change the angles at all.  There are
too many facets that are right at Quartz's critical angle or below it.
Most Quartz designs do very well in CZ by not changing the angles.  The
Scissors cut seems to be a very good candidate for leaving well enough alone.


What do others think?  Here's the design.

Regards, Dennis Anderson in Sunny Southern California

GemCad 5.0
g 96 0.0
y 2 y
I 1.54
H Scissors
H Livingston, Bob; MDR Book of Gem Cuts v1 n16
H Vargas, G & M: Faceting for Amateurs (1969) p154
H Vargas, G & M; Diag for Facetint (1975) p76
a -90.000000 0.58370000 96 48
a -90.000000 0.94851000 24 72
a -90.000000 0.98906000 12 36 60 84
a 46.020000 0.41233000 96 48
a 33.500000 0.53665000 12 36 60 84
a 35.000000 0.38387000 2 46 50 94
a 14.680000 0.30032000 96 48
a 35.300000 0.56835000 22 26 70 74
a 28.390000 0.50701000 24 72
a 42.130000 0.62803000 24 72
a 0.000000 0.24677000 96
a -47.790000 0.46990000 96 48
a -42.930000 0.47391000 95 49 47 1
a -41.000000 0.47522000 96 48
a -36.290000 0.62819000 84 60 36 12
a -39.100000 0.70247000 78 66 30 18
a -31.250000 0.68788000 72 24
a -52.670000 0.78634000 72 24

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Message:03

Subject: RI and Tangent Ratio Conversion
Date: Sat, 6 Dec 2003 17:08:23 +1000
To: <faceters@caprock-spur.com>
From: "Arch & Jan Morrison" <archnjan@serv.net.au>

SNIP <Lets have a rousing discussion about R.I. and Tangent Ratios. How
do you
do yours, is it necessary for all stones, does it really matter a few
degrees one way or the other, and what stones or designs benefit most.>
SNIP

I think this is a great subject for a weekly discussion topic and I'll
have an early bash at some comments for you.

If you are doing a simple cut like an SRB then you can get off with just
changing all angles by the same amount. But for more complex designs,
this simple method will change the relationship of the facets to each
other and you need to use a more complex conversion method called
Tangent Ratio Conversion.
I do my Tangent Ratio Conversions the easy way by using the Gemcad
Program - Edit Menu/Tan Ratio  which changes all facets at one time.
(however this means that you have to have downloaded this program and
also have your cutting design in a format that this program can read).
If you have neither of these then there is an online Tangent Ratio
Converter at  http://www.amfed.org/faceters/faqs_tangent_ratio.shtml . I
haven't used it but it looks OK.
With regard to general information on this and other faceting subjects,
the Bob's Rockshop site at
http://www.rockhounds.com/rockshop/gem_designs/article_index.shtml   is a
good source. ( It also contains an article by Charles Moon called "More
Tangent Ratio Fun" and an article by Jeff Graham "What is Tangent
Ratioing" which gives another point of view and points out the
limitations).
The reason you need to change the angle in the first place is because
different materials have a different Refractive Index. This changes the
Critical Angle (CA). Light hitting the material surface at less than the
CA will be refracted while light hitting the material surface at more
than the CA will be reflected. Materials with a high RI have a lower CA
and therefore can be cut for internal reflection with lower facet
angles. The important point about this is that cutting designs where the
angles have been optimised for high RI materials will not perform well
for low RI materials and, in many cases will probably "window" (where
the light entering the top of the stone is not reflected back out the
top but is refracted out the back of the stone). So in these cases you
would have to change the primary Crown and Culet angles to what is
correct for your material and then Tangent Ratio all other Crown and
Culet angles to retain facet relationships.
Those who use designs listed in DVue should bear in mind that the
"default RI" which was used is the Quartz RI of1.54. This gives the
impression that many of the designs can be cut in Quartz or other low RI
materials - but it aint necessarily so. Some of the "1.54" designs were
actually designed for a higher (but unknown) RI. The only way to be sure
is to run something like the Gemcad Waytwace program and see if the
light exits the back of the stone.
Arch Morrison
Buderim, Queensland, Australia.

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Message:04

Subject: Tangent ratio
Date: Sat, 6 Dec 2003 02:26:12 -0800
To: "faceters digest" <faceters@caprock-spur.com>
From: "Jerry Newman" <gemartserv@dc.rr.com>

Hi Thurmond,   Whenever I need to TR a diagram I use the handy paper
slide rule I made from a Robert Strickland article published in Angles
in 1996.  Every faceter should have this.  It's very slick. I'll try to
send as an attachment, but I'm not sure  you can receive it. If it
doesn't get to you perhaps Robert can somehow get it to you properly so
faceters can access it.    Regards,   Jerry Newman

_______

Hi Jerry,  The list blocks attachments for security reasons. Send them instead
to owner-lapidary@caprock-spur.com .

Thurmond

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Message:05

Subject: tangent ratio
Date: Sat, 6 Dec 2003 12:38:10 -0000
To: <faceters@caprock-spur.com>
From: "Daniel Hargreaves" <danny@blueyonder.co.uk>

Attached is a word file which lets you read off the old and new tan ratio
angles. This is a retype from a photo copy of calculations by an
Australian faceter. I can't remember his name at the moment but the
original was published in a magazine. Use the old and new critical
angles and go down both columns till you can read the old angle then
look across for the new one.

                  Yours Danny

http://www.gemcutters.org/documents/TA1.doc

__________________________________________________________
Message:06

Subject: Good article on the world's largest Imperial Topaz Mine
Date: Sun, 07 Dec 2003 07:09:37 -0200
To: LapidaryArtsDigest <lapidary@caprock-spur.com>
From: Robert P Lowe Jr <robertplowejr@uol.com.br>

07 December 2003

Since I've never gotten around to posting the pictures of my visit to
the Capao Mine - here's a good article with a few good pictures also

http://www.gia.edu/newsroom/issue/2798/2029/insider_newsletter_details.cfm#4#  

Insider Gemologist Visits Capao Mine in Brazil

Best regards,
Robert Lowe
Lowe Associates - Brasil
Gemstones, Rough, Specimens
Tucson - February 5 - 10, 2004 - GJX # 205
e-mail: USA    <robertplowejr@juno.com> February 2004
e-mail: Brasil <robertplowejr@uol.com.br>

__________________________________________________________
Message:07

Subject: Silent Faceters
Date: Sun, 7 Dec 2003 14:55:48 -0800 (PST)
To: LAPIDARY ARTS & FACETERS DIGEST <faceters@caprock-spur.com>
From: Glenn Klein <glennklein@yahoo.com>

Hi All:
 
I  am beginning to not like the way things are going in our Faceters World. 
This has been a bad year for losing some of our top faceter contributors of
years past.  We have lost Walter Carss, Fred Van Sant, Cliff Jackson, and
now I received an email from Doris Unruh that Carl Unruh has also gone to
faceters Heaven.  Carl passed away last Tuesday.
 
Carl and Cliff were of the fantastic group of the Northwest who have faceted
the VERY large gemstones.  Carl was also from that group of us faceters who
came from the Mysterious Faceters Triangle area in central Kansas.  John
Alden was one of the group as well.  He is long gone now.
 
I have had the pleasure of knowing Carl since the early 1970's.  I, for one,
will certainly miss his pleasant company at faceters gatherings.  I got him to
come and give a presentation at the 1996 and 2000 Faceters Symposiums
here in California.  I tried to get him to come and speak for the third time....at
Ventura last June, but Carl was too sick to travel.  Carl used to publish a
small magazine for faceters in the old days.  The magazine was filled with
tidbits of faceting information....much like what we do now with our posts
to the chat pages. 
 
Somewhere, we are going to have to recruit some new and younger faceters
to carry on the good work that has gone before.  These days it seems like the
younger people as a group do not want to get into faceting guilds or into making
up case displays of stones, etc.  That is too bad, because I think they are missing
a lot by not getting involved.  Just getting involved with a guild will introduce you
to some swell people.....FACETERS.
 
There has not been a time in my life when I made such a group of fine friends as
I have done by meeting faceters at the various gem shows and gatherings. 
There is no finer group of people in my humble opinion.  Heck, sometimes I even
like some of the Australian competition faceters.
 
Glenn Klein
Lake Forest, CA USA

__________________________________________________________
Message:08

Subject: Tangent Ratio
Date: Mon, 8 Dec 2003 20:35:54 +1000
To: <faceters@caprock-spur.com>
From: "Arch & Jan Morrison" <archnjan@serv.net.au>

SNIP<Well I'm trying to do another CZ emerald and the only design I can
find
I like is a Scissors in quarts.>SNIP
Chuck,
I found your Scissors Emerald design in DVue2 (04.005 for anyone
interested) and put it into Gemcad and played with it.
For the pavilion, the original angles in sequence are
47.8-43-41-36.3-39.1-31.3 and 52.7. Choosing the 41 degree as the
primary facet (it's the one at the culet) and changing that to 35
degrees, Gemcad gave 41.6-36.8-35.0-30.6-33.2-26.1-46.6. On the crown
the original angles are 46-33.5-35-14.7-35.3-28.4 and 42.1. Converting
the 46 degree facet to 41 degrees Gemcad gave
41-29-30.4-12.4-30.7-24.4-37.2. So you can use these figures to check
your other ways of doing the calculation. However, I wouldn't use these
to cut your stone for the reasons below.
This design doesn't seem to have been designed for Quartz. It is one of
the many in DVue that I mentioned in my previous post. When I used an RI
of 1.54 and ran the ray-tracing check (waytwace) a lot of rays were lost
out the back of the stone (so it was possibly designed for a higher RI
in any case).
When I changed the RI to 2.2 and changed the Pavilion and Crown angles
to the Gemcad angles given above, the raytracing results were
disappointing - lots of light lost out the back and lots of multiple
reflections inside the stone (which would compound the issue by reducing
the brightness of the rays which were returned through the Crown).
The best results were obtained by changing the RI to 2.2 but keeping the
original angles. The raytracing run on this variation showed light still
being lost out the back of the stone but nowhere near as much as in the
other two runs. [Note that keeping the original angles when using a
higher RI material than the design was done for conforms to the
suggestion in (the previously referred to) Jeff Graham article.]
HTH
Arch Morrison
Buderim, Queensland, Australia.

__________________________________________________________
Message:09

Subject: FRESH AIR
Date: Fri, 05 Dec 2003 15:15:23 -0600
To: LapidaryArtsDigest <lapidary@caprock-spur.com>
From: Doug Smith <gembin@spiff.net>

Hello Frank,

Relating to "Ann Rea's Son", what a breath of fresh air! Do you know if
this is a true story? Is this someone you know? It amazes me that I hear
American Muslims publicly condemning the USA, but never publicly
praising the USA. To me, they are mysteriously quiet about condemning
the Muslin terrorists groups and those that support them..

I would be most happy if you would give me permission to copy this story
and email it to everyone I know (encouraging them to forward it to their
friends) and also submit it to our local newspaper. Perhaps if this
story were publicized extensively, it would encourage patriotic American
Muslims and those around the world to support the USA by publicly
condemning terrorists and the thugs fighting us in Iraq.

Best Regards,
Doug "Rhodolite" Smith
Alton IL, USA

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Message:10

Subject: weeweechu
Date: Sun, 07 Dec 2003 20:56:00 -0600
To: Ounnie <ounnie2002@yahoo.com>
From: Downey <alckytxn@swbell.net>

One beautiful December evening Huan Cho and his girlfriend Jung Lee were
sitting by the side of the ocean. It was a romantic full moon, when Huan
  Cho said "Hey baby, let's play Weeweechu."

"Oh no, not now, lets look at the moon" said Jung Lee.

"Oh, c'mon baby, let's you and I play Weeweechu. I love you and it's the
perfect time," Huan Cho Begged.

"But I rather just hold your hand and watch the moon."

"Please Jung Lee, just once play Weeweechu with me."

Jung Lee looked at Huan Chi and said, "OK, we'll play Weeweechu."

Huan Cho grabbed his guitar and they both sang.....
         "Weeweechu a Melly Clistmas,"
         "Weeweechu a Melly Clistmas,"
         "Weeweechu a Melly Clistmas,"
         "and a Happy New Year."

...AND SO DO I!

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Post something from your experiences in gemcutting today!
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TODAY'S FUNNY ~

From: Doug Smith <gembin@spiff.net>

 ~ Time Off?

Two factory workers were talking.
 
"I think I'll take some time off from work." said the man.
 
"How do you think you'll do that?" said the blonde.
 
He proceeded to show her...by climbing up to the rafters, and hanging
upside down.
 
The boss walked in, saw the worker hanging from the ceiling, and asked
him what on earth he was doing?
 
"I'm a light bulb" answered the guy.
 
"I think you need some time off," said the boss.
 
So, the man jumped down and walked out of the factory.
 
The blonde began walking out too.
 
The boss asked her where did she think she was going?
 
The blonde answered, "Home. I can't work in the dark."

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TIDBITS AND REFLECTIONS~

I have learned from experience that
the greater part of our happiness or misery
depends on our dispositions
and not on our circumstances.

---Martha Washington---

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