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LAPIDARY ARTS and FACETERS DIGEST
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Issue No. 87 - Monday March 17, 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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From the Moderator: 

Topical Focus for This Week:

GARNET and DARK STONE CLINIC

HOMEWORK for this tonight:

For each night this week, put on your thinking caps and share your experiences,
pains and pleasures in cutting Deeply colored Garnet and other Deeply
saturated stones.

Consider the following while you compile your responses.

1. Cutting garnet and other stones in the various color saturations

2. Intent:  cutting "bright and lively" stones, from rough that reaches
50% saturation (white paper test limit), or darker.

3. How approaching or exceeding the critical angle, or other parameters, might
help accomplish this.

4. Known cuts that perform well in darker garnet rough.


Phil in Florida submitted this topic for the first of a new series of week
long topical "clinics"  or group "brainstorming sessions".

_______

HI all,  Today is the official kick off of our new problem solving series.
Our first topic for this series is cutting Garnet and other Dark or strongly
saturated stones with the intentions listed above.

Thurmond
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Index to Today's Digest

01  RE: Cactus,opals and doughnuts (was "Opal Dirt")
02  RE: Garnet and Dark Stone Clinic
03  RE: Garnet and Dark Stone Clinic
04  RE: Garnet and Dark Stone Clinic
05  RE: Garnet and Dark Stone Clinic
06  RE: Photographing Opals

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Message:01

Subject: Inre Msg 6 of Issue 86
Date: Sat, 15 Mar 2003 07:42:21 -0700
To: <lapidary@caprock-spur.com>
From: "Paul Miller" <phmiller@corlink.com>

All you folks working with your donut seeds, opal dirt, etc., better be
careful where you step lest you get snowman "poop" (aka marshmallows)
all over your shoes.  Paul

__________________________________________________________
Message:02

Subject: GARNET and DARK STONE CLINIC
Date: Sat, 15 Mar 2003 11:39:49 -0500
To: lapidary@caprock-spur.com
From: Kenda Wright <kendaw@worldnet.att.net>

What a great topic.  I love garnet, the way it cuts, the way it polished
and especially the way it flashed.  I've been particularly interested in
getting this high color saturated stone to perform better.  Many of the
comments I've heard certainly are contradictory to my experiences
cutting garnet.  I designed a cut that probably wouldn't make sense to
most yet, it has more brightness and flash than any other I've cut.
I'll post the cutting diagram on my website for anyone to cut.  And, if
you want to see a picture of one, look at stone on the top row second
from the right on the 28 stone tray on my home page
<http://home.att.net/~GemCutting/wsb>.    I have some better close up
pictures I can send if anyone wants to see them, just send me an email.
The pavilion is very very deep and has many step facets and some star
facets.  The crown is also very high although I have designed a second
cut with a lower crown that seems to show well on GemRay but, I have not
cut it yet.   Great topic.  I look forward to what everyone else has
found works best for them.

John, Lexington KY

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Message:03

Subject: dark garnets
Date: Sat, 15 Mar 2003 10:17:38 -0800 (PST)
To: LapidaryArtsDigest <lapidary@caprock-spur.com>
From: Dave Thompson <djt@irastro.caltech.edu>

> The light needs to be returned in a minum number of bounces since each
> bounce causes energy loss in dark material. Please correct me if I am in error
> with this line of thinking.

As long as you are above the critical angle on the internal
reflections, the number of bounces is not important (total internal
reflection = 100%).  The absorption of light is proportional to the
total path length traveled through the stone.  In a thinner stone,
you have a shorter pathlength, so there is less absorption and you
have a brighter stone.

Dave (Pasadena, CA).

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Message:04

Subject: Dark garnet problem
Date: Sat, 15 Mar 2003 17:56:38 -0500
To: faceters@caprock-spur.com
From: Dan Clayton <dclayton@speakeasy.org>

Phil and Thurmond,

I think you have agreat idea to address the problem of how to cut
dark garnets to get the brightest possible stone. I am not alone
because one of my online friends asked me check his design with
BOG and GemFramX. This post will deal with my thoughts on
dark garnets and computer testing designs for them.


I don't trust GemFramx or BOG much with dark garnets until I can
see that they actually factor in saturation. I think a friend is working
on some code that will take saturation into account in raytracing. I
am almost certain it is not ready for use by the general public. you.
probably need to be a certified nerd at this point to make it work
I am sure there are other factors but I think you can keep close to
critical angle and use low crown to get pretty good performance on
dark garnet. I think you can still use BOG and GemFramX but ignore
the numbers look at the light pattern ten cut a test stone to confirm your
designs. I think POV may work better fhan either of the other packages
for dark garnet but I do not know.  I think you just want a design close to
critical angle with a fairly low crown that gives a good pattern of light

You don't want dark areas with no light return but I don't trust any
numbers until I can confirm it myself. Your test stone is the ultimate
test. I am a big believer in raytracing gem designs but in this case
I think it is of limited use. If someone knows the solution please
share it on the list.

My best solution is to cut lightly saturated garnet.

Happy cutting from Puyallup where spring may be on the way.

Dan Clayton


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Message:05

Subject: Re: Garnets and cuts
Date: Sun, 16 Mar 2003 11:19:24 -0800
To: lapidary@caprock-spur.com (LapidaryArtsDigest)
From: Tony <lightbender@thegemdoctor.com>

Hello Thurmond,

I really haven't been tempted to spend much time with dark garnet
as it is not particularly rewarding neither emotionally nor
financially.  I have repaired many, and have seen how various
cutters have sought to make them attractive. I have seen only
very small stones that have any good brilliance to them when
conventionally faceted.  Mike in Florida has pictures that
illustrate the problem nicely the two dark garnets show about 50
percent occlusion. It looks Mike has succeeded in getting the
most life out of them though.

The tricks that I like are hollowed out cabochons, buff cuts and
doublets. Buff cuts don't lighten the stones but the floating
facet reflections are always intriguing. Lots of thin pavilion
facets work well with this cut.

IMHO
Tony.

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Message:06

Subject: Re:Photographing Opals
Date: Sat, 15 Mar 2003 11:17:36 -0800
To: lapidary@caprock-spur.com (LapidaryArtsDigest)
From: Don Rogers <Don@Campbell-gemstones.com>

At 11:19 PM 3/14/03 -0600, you wrote:
>I have just taken some nice pictures of  a pair of opal earrings.  I
>using a Panasonic PV-SD4090 superdisk with a cheap General tools 5X
>plastic loop over the lens (this is very close so that it is inside the
>focal length of the loop) and used offset lighting to get the fire to
>show well and no flash.

There was a trick for photographing opals, and other cabs, posted on the
Orchid net about a year ago.  Place the stone/jewelry in a white bowl and
cover with water. If you eliminate the glare off the surface of the water,
there will not be any light spots or glare on the stone or
jewelry.  Doesn't work well with faceted stones though as all you get from
the stone is the color.

Don Rogers

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TODAY'S FUNNY ~

ADVICE FOR IDIOTS

An actual tip from page 16 of the Hewlett Packard
Environmental, Health & Safety Handbook for Employees:
"Blink your eyelids periodically to lubricate your eyes."

IDIOTS IN THE NEIGHBORHOOD

I live in a semi-rural area. We recently had a new neighbor
call the local township administrative office to request the
removal of the Deer Crossing sign on our road. The reason:
Many deer were being hit by cars and he no longer wanted
them to cross there.

IDIOTS & COMPUTERS

My neighbor works in the operations department in the central
office of a large bank. Employees in the field call him when
they have problems with their computers. One night he got a
call from a woman in one of the branch banks who had this
question: "I've got smoke coming from the back of my terminal.
Do you guys have a fire downtown?"


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REFLECTIONS AND TIDBITS:

" In the long run you hit only what you aim at,
Therefore AIM HIGH."

--- Henry David Thoreau ---


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