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LAPIDARY ARTS and FACETERS DIGEST
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Issue No. 308 - Friday, November 5, 2004
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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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Hi everyone,

Here is this week's issue.
Enjoy and have a great weekend.


Thurmond
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Index to Today's Digest

01  RE: Rust on laps
02  RE: Peridot
03  RE: Rust on laps
04  RE: Diamond cutting
05  RE: Heat treating Zoisite
06  RE: Heat treating Zoisite
07  FS: New Shipment of jade from Siberia
08  NEW: chrysoprase pricing
09  BIO: kathy bryan
10  RE: Rust on laps
11  NEW: Show announcement

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Message:01

Subject: Rusty laps
Date: Fri, 29 Oct 2004 17:17:04 -0700
To: <lapidary@caprock-spur.com>
From: "The Newmans" <gemartserv@dc.rr.com>

Hi Gail and all,
My old trusty 600 grit topper which I use regularly for faceting is
stained and rusty and has been for a year or more. It is not a problem. 
I've even gone directly to polish on quartz or sunstone....it is very
well broken in. Today I even cut a couple of small sapphires in it. On
these and other harder stones than quartz I will prepolish after the 600
with a 3000 or possibly a 1500 dynadisc before polishing. Hope that
helps.
Jerry Newman

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Message:02

Subject: Peridot comparison
Date: Fri, 29 Oct 2004 17:36:46 -0700
To: <lapidary@caprock-spur.com>
From: "The Newmans" <gemartserv@dc.rr.com>

I've cut a fair amount of San Carlos and think it is as good as any
other.  It is true that it is limited in size.  It is hard to cut a
finished stone in the 4 to 5 ct or larger range. I've never had a
problem polishing it, although I've heard that some do, but I'm not sure
this is unique to San Carlos. I've also cut and sold some very nice
Chinese. It too was not all that large.  It seems to be true that
Burmese comes in much larger sizes as does the Pakistani material. I've
cut some big, ie. 10 to 20 ct Burmese.  There is a tendency for some of
it to be "sleepy" due to very, very fine needles in my experience.
Haven't cut Pakistani material, but from what I've seen the San Carlos
material isn't inferior in color.  I would expect all deposits show some
variation in color. The stuff I collected and cut from Dish Hill in the
Mojave Desert of Calif. varies from greenish brown to yellowish green to
apple green.
Just one cutters experience.
Jerry Newman

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Message:03

Subject: Re: Rust on laps
Date: Fri, 29 Oct 2004 20:09:15 -0500
To: "LapidaryArtsDigest" <lapidary@caprock-spur.com>
From: "Criss Morgan" <crissmorgan@bellsouth.net>

Hi Gail,
             The rust really shouldn't present a problem unless it's real
bad. By the time you get a preform made for a cabochon all of the rust that
might get in the way will have all been ground off. I once bought a quantity
of used laps, and a few of them had rusted on the surface. The only one
which gave me any problem at all was one that developed some deep pits
because of the rust. The others only had a light coat of rust and the first
time I used them it disappeared.
                       Criss

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Message:04

Subject: Re: diamond cutting
Date: Fri, 29 Oct 2004 19:27:10 -0700
To: lapidary@caprock-spur.com (LapidaryArtsDigest)
From: Tony <lightbender@thegemdoctor.com>

Hello Brian.

I spent about the price of a top end luxury motor car buying a
diamond faceting setup. 3 hp motor, 12" Meehanite iron lap, a
small selection of mechanical claws. I think with a lot of
practise I could have reduced faceting time to below the time it
takes to cut about 100 sapphires. I know a couple of top notch
diamond cutters that can bang out an SRB in about the time it
would take me to cut about 35 sapphires.

The biggest reason diamonds are so cheap is because there is not
a lot of money to be made cutting them. Spending a $100 on rough
and about $10,000.00 in time and get a stone that will sell for
5 - 6 thou.  Gabi Tolkowsky went to work every day for 4 years
cutting the Millenium Diamond,  quick eh?  but then he's a very
experienced cutter. Why do you think DeBeers sells rough for
only a few bucks a carat?

Tony.
I'm not bitter.

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Message:05

Subject: Re: NEW: Can Zoisite be heat treated?
Date: Sat, 30 Oct 2004 00:04:08 -0500
To: "LapidaryArtsDigest" <lapidary@caprock-spur.com>
From: "Rough Ventures" <info@roughventures.com>

Tom,

Of course Zoisite can be heat treated, but it must be done properly.  As
of current record, facet grad, gem zoisite comes from 2 sources in the
world: Tanzania and Pakistan:

1) Tanzanian material:  It is best to cut the rough before you heat
treat for complex reasons I can't explain in this newsletter.   If you
must treat the rough before you cut, make sure that it is at least
eye-clean under 10X.  Place the stone in either activated charcoal (you
can find this in the fish supply section of Wally World or any major pet
store), or aluminum oxide (same stuff you use to polish your gems with).
 You can use the cheaper, course grade aluminum oxide if you want to
save money (it won't make a difference in the outcome of your stone if
the oxide is fine our course grade).  Basically, you need a "heat sink"
for your zoisite, so that the heat you use to treat the stone  with does
not rapidly heat up and then rapidly cool, which will result in
thermodynamic shock...shattering your gem/rough!  You can even use clean
sand, or even ash from a recent barbecue or campfire.  I have even heard
of people using investment casting...I personally recommend aluminum
oxide or charcoal.

Take an old coffee can (1 lb. preferably), hopefully with the top cut
off and the bottom still in tact, and fill it half full with your
preference of heat sink material.  Next, place your stone in the center
of the can on top of the heat sink material, and then fill the coffee
can to the top with more heat sink material.

Place the filled can with your stone inside your kiln.   Slowly heat the
kiln, over a 6 hour period, to 500 C (923 F), increasing the temperature
from room temperature (usually 22 C) to 500 C, at a rate of ~80 C every
hour.  Once you reach 500 C, hold the temp. for one hour, and then
slowly decrease the temperature at the same rate you brought it up (~80
C/hour).  If you have an expensive kiln that is properly insulated, once
you reach 500 C and hold for an hour, you can simply turn the kiln off,
and it will loose heat at a rate sufficient enough to prevent your stone
from cracking.

I have heated zoisite(tanzanite) a million times, and I have only
cracked one stone (when I first started, using another dealer's
recommendations).  Since then, I have used the process I explained
above, and I have yet to have a problem.  Of course I don't treat
included or "crunchy" rough/cut stones, so I minimize my risk.  Trust
me, if your gem/rough is clean, you have a good heat sink to protect
your stone, and you slowly ramp up and then ramp down the temperature,
heat treating is a breeze.  I suggest starting early one Saturday
morning, reach your temp. over 6 hours, shut the kiln off once you have
held the temp. for an hour, and then let the kiln sit until Sunday
morning.  Do not rush the process!  If you get impatient, or heat the
stone up too fast, or cool it too fast, it will crack/explode on
you...it is a matter of thermodynamics.

2) Pakistan Zoisite:  I have tried on 5 occasions to heat-treat material
from Pakistan.  The root-beer colored material from Gilgit, does not
seem to heat treat at the same temperature or conditions that the
Tanzanian material does?  I have also tried heat treating the greenish
brown material from Gilgit with no luck.  However, I do have a very
large specimen of dark purple zoisite from Pakistan that my dealer
swears is natural.  So the gem obviously occurs in the purple color, but
I do not think that heat treatment conditions similar to those of the
Tanzanian material are sufficient...I will of course experiment more and
keep everyone up to date :-)

If you have any more questions, problems, or even need heat treatment,
please drop me a line!  Good luck with your experiments!

Sincerely,

John Thielmier
www.roughventures.com

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Message:06

Subject: Re: Doisite
Date: Fri, 29 Oct 2004 22:36:55 -0700
To: lapidary@caprock-spur.com (LapidaryArtsDigest)
From: Don Rogers <Don@Campbell-gemstones.com>

At 06:18 PM 10/29/2004 -0500, you wrote:
>    Can anyone tell me if Doisite can be heat treated to turn it into
>Tanzanite?Or possibly close to Tanzanite color?

Tom, I am assuming that you meant Zoisite.  In any case, the answer is that
Tanzanite is a variety of Zosite,  You can heat treat Tanzanite to improve
its color, but not it's clarity.  You can not heat treat non gem Zosite to
gem Tanzanite.  This includes the green zoisite and ruby that is common.

Untreated Tanzanite can be anywhere from a yellow/brown to a pale
purple/yellow colored stone.  Heat treating these will change the color to
a stronger blue/purple color.  Each stone is unique and you will only know
what the final color is after treating.  There is no process that I know of
to treat all stones to a given color.

When heat treating tanzanites though, you should be aware that more than
the color is affected.  The treated stones tend to be difficult to cut and
polish as they are much more brittle than the natural stones.  The facet
junctions can start to look like Blue Zircons (also heat treated for the
most part).

You could try some of the Zoisite and ruby mix, but there are also other
elements involved, IE epidote and feldspars which may not survive the
heating.  Even if you could change the color a bit, the clarity would not
be changed.

Don


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Message:07

Subject: New Shipment of jade from Siberia
Date: Sun, 31 Oct 2004 01:47:32 -0400
To: lapidary@caprock-spur.com
From: "Richard Rosenthal" <kenaii@earthlink.net>

A new shipment of Black , Blue-green, Bright -green,Highly transparent
grey -green, and catseye jade has arrived for processing and sales at 
the Whitewolf Trading Company facility in Pennsylvania.  Initial pictures
are posted at http://groups.msn.com/Ravenwolf  I will be posting more
pictures and information through out the week as I work my way through
the load.  For Specifics please write to kenaii@earthlink.net
Thanks  for any who recieved this e-mail and are not interested in jade
my apologies, this is not spam all addresses were gleaned from my own
address book exclusivly. If you do not wish to recieve this or further notifications
as new materials arrive please send me an e-mail at the above link with the
words remove in the subject line and I will take you off my list. For those of
you interested in more information on Siberian Jade please check out my
home site at http://wwww.catseyejade.com 

Thanks again, Best Wishes
Richard Rosenthal
kenaii@earthlink.net

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Message:08

Subject: Re: Issue No. 307 - Friday, October 29, 2004
Date: Sun, 31 Oct 2004 22:58:37 EST
To: lapidary@caprock-spur.com
From: VESteele@aol.com

Hello list,
   A friend has about five pounds of chrysoprase that he has had for quite a
while that he may sell.  He is wondering what it might be worth.  He describes
it as being a very good grade.
   Virginia (Indiana)

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Message:09

Subject: kab jewelry and rock shop..aka kathy bryan
Date: Tue, 2 Nov 2004 17:01:09 -0800 (PST)
To: lapidary@caprock-spur.com
From: kat b <kabwy1957@yahoo.com>

a little about me i have been faceting and cabbing for
17 years, i own what i call a smorgasbord rock
shop,that is 70-80 years old i have allot of hard to
find gems..i also for 17 years have been doing silver
and gold smithing,casting jewelry for a year and a
half,i do beading,have since i was 12 and i also sell
beads and teach beading in person and over the net, i
live in Wyoming, there is allot of good places for
rock hunting here if your ever in Wyoming in the
summer and would like to know where there is some good
spots let me know thanks Kathy Bryan

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Message:10


Subject: rusty laps
Date: Wed, 3 Nov 2004 17:42:53 -0500
To: <lapidary@caprock-spur.com>
From: "ray lahti" <lahtirl@msn.com>

To Gail Bumala,

The light rust on the laps is not a problem particularly if they are of
a coarser grit.  To avoid getting rust on a stone I want to work, I
would first grind a piece of quartz with a lot of water as a lubricant
just long enough to clear the laps of rust.  Wiping the discs with a
cloth or paper towel could get some of the loose rust off but may leave
a residue.  Grinding a piece of agate or quartz will thoroughly remove
the rust as the lubricant (water) washes it away.

Ray Lahti

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Message:11

Subject: Melbourne, Florida Gem Show November 13-14
Date: Thu, 4 Nov 2004 04:33:47 -0800
To: faceters@caprock-spur.com
From: Phillip L Stonebrook <plstonebrook@juno.com>

Greetings....

For all faceters in the central eastern section of Florida, the Melbourne
Gem and Min. Soc. is again putting on our yearly gem show in Melbourne,
Florida at the Melbourne Auditorium, 625 E. Hibiscus Ave. The dates are
November 13-14, from 10AM to 5PM Saturday and Sunday. We will have
faceting rough vendors there, and I will also be displaying my personal
gem cut collection, including the USFG SSC "Carousel" winner for 2003.

I'll be at the faceting demonstration table with our new 2005 club
president, Bob Lombardi, who will also be there with his Facetron cutting
corundum. Stop by and say hello. Hope to see you there.

God bless....
Phil in Florida

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