Edited and Published by Hale Sweeny
Web Site:
Associate Editors: Geo. Butts, JR Shroeder, Steve Henegar
and Margaret Malm

This list digest contains the following message subjects:

1. LapDigest News for Issue No. 213 - Thurs 6/17/99
2. REVIEW: Lapidary Journal(LJ) for June 1999
3. NEW: High Speed Engavers for Lapidary Work
4. RE: Polishing Watermelon Tourmaline Slices
5. RE: Polishing Watermelon Tourmaline Slices
6. RE: Spool Machine Information
7. RE: Making Diamond Core Drills
8. RE: Making Diamond Core Drills
9. RE: Corundum- Cutting and Shaping Ruby/Sapphire
10. RE: Polishing Obsidian
11. RE: Searching for Nephrite Headstone
12. BIO: David Blackman
13. BIO: Mining Center Peru
14. BIO: Cortney Mayle
15. WTB: Calico Agate
16. WTB: Cabbing Services


Subject: LapDigest News for Issue No. 213 - Thurs 6/17/99

When you send a query to Lapidary Digest, please only send
one query per message. When you send an answer to a query
to Lapidary Digest, please only send one answer per message.
This will make life a lot easier for me! Thanks

Am going to take off a couple of days next week for a small
trip, but the Digest issues should come out on time.

Take care of yourselves, and be sure to hug and kiss the
ones you love. ... And have FUN!


Subject: REVIEW: Lapidary Journal(LJ) for June 1999

On Crystal Shores. Page 32: Fred Ward has written a short
article on alternative locations to find rough that we may
not have ever thought about. There are beaches all over the
world that are known to produce small yet very nice rough.
>From agate to quartz to sapphires to zircons can be found
at beaches. For locations, The International Sand Collectors
Society may be a source over and above the ones listed in
the article. Their e-mail address is

So "Next time you find yourself on a beach with someone you
love and he or she mentions gems, I suggest you begin your
search right under your feet."

Sticks & Stones. Page 36: Annie Osburn spent some time with
jewelry designer and gallery owner Micky Roof, who has found
a way to combine free form stones and gold sticks into
wonderful creations. She seems to have a flair for using
opals. If you have some stones that are not 100% color and
have wondered what to do with them, check out this story.

Like Fine Wine, Page 40: Si & Ann Frazier have provided the
amethyst lover a great resource. Amethyst has a high
sensitivity to heat. To understand what makes the lovely
purple color and how easy it can vanish when exposed to
heat see the full text of the article. They provide in-depth
answers to 10 popular questions about Amethyst.

Heading West, Page 53: Chris Rose and Judith H. Rose spend
a little time talking about some of the best rockhounding
locations in the US that are open to the public. Virgin
Valley Nevada is just one of the locations they talk about.
A few years ago a fee digger found a huge 220 pound log.
What makes it such a great find was that it was filled with
precious opal. A company called High Desert Gems and
Minerals is giving rockhounds the chance to find the rough
that they have dreamed about finding for years.

Diamond-Shaped Opal Intarsia, Page 67: Tom Benham provides
a Beginner-to-intermediate project that any opal lover would
like to have. It uses 1 Blue-green center stone, 4 strips of
white opal, 4 strips of lapis lazuli, and a thick slab of
lapis lazuli. The instructions call for using both a flat
lap and grinding wheels.
JR & Janet Schroeder
J & J Jewelry

Subject: NEW: High Speed Engavers for Lapidary Work

Has anyone had any experience with using high-speed
engravers? These are essentially dental drills which turn
at a very high speed (~400,000 rpm) and are powered by air.
>From what I have read in WOOD and other magazines, they
engrave a wide variety of materials, including wood, glass
and metal. The magazine rated the SCM tool as the highest
rated one, but I am sure there are others also adequate.
They need a separate air compressor and the engravers are
all quite expensive.

Has anyone used them for engraving on rock slabs or for
other lapidary purposes? I would appreciate hearing from
you about your experiences with these tools on any lapidary


Subject: RE: Polishing Watermelon Tourmaline Slices

Janice wrote:

<<I have some watermelon tourmaline slices and I cannot get
the surfaces to polish with either cerium or tin oxide.
Can someone help?>>

Try using alumina on leather (was formerly called Linde-A)
or if you have a flat lap, use alumina on tin.


Subject: RE: Polishing Watermelon Tourmaline Slices

Linde-a on tin works in faceting.

Don at Campbell Gemstones

Subject: RE: Spool Machine Information

<<Do they work well? Are they as clean as advertised?>>

Yes they work, but clean is in the eye of the beholder.

Now let me try to give a more useful answer. The older
machines used maple wheels; the one the Graves sales uses
a phenolic wheel. I don't think there is much difference.
The wheel is very hard compared to the drums, wheels, or
belts that are more commonly used. This doesn't keep
it from working but it means you will need to retrain
yourself if you are used to a softer wheel. It is hard to
keep the surface of softer stones (6 down) from developing
flat spots. With harder stones (8 up) this is not as much
of a problem. With agate (7) I think it is a judgment call.
I'm sure people do agate (as well as softer stones) on them,
but I have had mixed results. Maybe I just learn slow.

They are clean in the sense that there is little or no
compound thrown from the wheel in operation, so working
on the kitchen table is possible. But the cabs are covered
with extender fluid that I think needs to be removed before
you can see if you have finished the current sanding step.
While it is not difficult to remove, it takes more than just
wiping it on a dry surface. I have to scrub them with
a brush and dish washing detergent. Maybe some of the list
members that have used them will share their technique.

The cabs need to be cleaned between sanding steps anyway
but cleaning them several times on the same step bothers me.
I would like it if someone will tell me a better way.

The compound kits that come with the machine stop with
50,000. This is OK for the harder stones but for many cabs
I find I need finer diamond or one of the oxides so I would
recommend a separate polisher. Also you will still need a
set of grinding wheels. When you add up all the extras, I
question whether you can beat the price of the "All in One

Dick Friesen

Subject: RE: Making Diamond Core Drills

This info is kind of related and may be of interest.

This info comes from an old text of mine entitled
Procedures in Experimental Physics, by John Strong. The
book was copyrighted in 1938. I believe that Lindsay
Publications currently publishes a paperback edition.

The book describes several devices used to cut glass for
laboratory and telescope work. These techniques are also
suggested for working with quartz crystals, for making
prisms and the like.

The first is a biscuit cutter - This is used for cutting out
optical blanks up to 6 inches in diameter, it is simply an
iron or brass pipe with a number of groves cut into the end
of the pipe, the cutout/groves appear to be about 1/4" wide
and about 1/2" deep, kind of like the top of a castle. The
pipe is held via a plug in the other end which is attached
to an arbor. The plug has several holes which lead into the
pipe, and the plug is recessed a bit into the free end of
the pipe. The operation is done in a drill press driven at
fairly slow speeds. SiC grit and water are fed through the
center to find their way down into the biscuit cut outs to
do the cutting. The author suggests 60 - 90 grade SiC, or
120 for fine work.

The second is a glass saw - It is along the same idea as the
Biscuit device except that a simple iron disk is used (no
groves but I can't see where they would hurt) The disk is
run through a mud consisting of water and SiC. Sort of like
a lapidary saw running through oil.

A variation of the mud saw is a diamond saw - It describes
how to make the blade. First the diamonds are pulverized in
a steel mortar and pestle (about 80 to 100 mesh (a 10" saw
will require about 4 carats of diamonds)). Next a 1/16"
thick copper disk is prepared by nicking the rim with a
knife and small hammer, the nicks are to be 1/16" to 1/32"
apart around the entire rim, I would guess about 1/16" deep).
Next the nicks are filled in with a mixture of the diamond
dust and wax. Finally the nicks are closed up by knurling
them over with a smooth steel roller, a slight burr should
be present to provide a kerf to the blade. A lathe is
required for the last step. The author suggest a rim speed
of 1000 fpm for cutting glass or quartz.

As far as thoughts to brazing diamonds, I believe that this
is done in a vacuum or inert atmosphere oven???


Jeff in Kalamazoo
The reprint of the book is available for $25 from Lindsay -
they have a webpage describing this book at
URL= hale

Subject: RE: Making Diamond Core Drills


I suspect your plan for making a diamond bore is going to
have problems because the diamonds will float in the liquid
solder making the bond difficult to achieve.

I have read some articles over the years that discussed
bonded diamond abrasives but could not lay my hands on them
when I looked. As I remember, the process to make them is
one from powder metallurgy. A nickel powder (possibly with
copper to make an alloy) and diamonds are mixed, pressed
into shape (might require more pressure than you can apply
by hand), and heated enough to sinter but not melt the mix.
This causes each particle to melt to the ones that touch it,
but since the mix does not melt completely the position of
the diamond blended in is not affected. I think this must
be done in an inert atmosphere (such as helium, like in
shielded arc welding) to keep the mix from burning as it is
heated. Thin layers give a better bonded surface than thick
ones. You end up with a coating that has diamond throughout
it so it continues to work as it is worn away by exposing
new diamonds.

Good luck with your project. I hope this helps.

Kreigh Tomaszewski

Please visit our family web pages at

Subject: RE: Corundum- Cutting and Shaping Ruby/Sapphire

Two things. First when cutting any hard material such as
corundum, you should use OIL as a blade lubricant. Also,
the RayTech 10 has a separate feed motor so there is not a
correlation between the blade revolution and vice movement.
It is very easy to over feed the saw causing blade damage.

Second, you might be able to revive the blade by tapping the
blade with the thin edge of a 10 flat file. I repeat: tap,
not hit. Make sure you tap at 90 degrees, and tap around all
around the blade. This will break the up the surface some
and allow the diamond to reappear. If you are using a plated
or sintered blade this won't work.

As to grinding with silicon carbide, don't. Corundum has a
9 hardness and silicon carbide hardness is around 9 1/4.
Diamond is the only way to go.

Don at
Campbell Gemstones

Subject: RE: Polishing Obsidian

I agree that the fracturing in obsidian, especially if it
gets too hot, can extend way down below the surface. But
that would lead to big scratches, not a "dull finish". I
fail to see why sanding/polishing obsidian needs to be so
complicated. It's the easiest material for me to work and
polish, provided you keep it from heating up.

I use a dull 100 belt, a dull 220 belt, and optical cerium
oxide on a bull wheel. That's it. Perfect polish every time.
You don't even need 600 or 1200. Obsidian is so soft it's
very easy to take out scratches from dull 220 in the
polishing step. Sharp belts leave big, deep scratches, but
I have done cabs on diamond wheels and they don't seen to
leave appreciable scratches, so maybe it's the quality of
the sanding belts.

Tim Fisher
Ore-Rock-On and Pacific Fishery Biologists WWW Sites
See naked fish and rocks!

Subject: RE: Searching for Nephrite Headstone

There is an extensive article by Fred Ward titled " The
Great Green North " on " Polar Jade " in Colored Stone
magazine. Volume 12, No.2, March/April 1999.

The photographs in the article show pieces of nephrite quite
large enough for making headstones and on checking their web
site I see that they market tables made from the material -
so I guess they have the capacity to cut something as big as
a headstone.

The only contact I have for this material is their web site .

I hope this will be of assistance to the subscriber needing
a headstone.

Craig White
Chrysoprase Mines of Australia
Thanks, Craig. Now a chrysoprase table top (suitably
reinforced, of course) - that would be stunning!! (smile)

Subject: BIO: David Blackman

I am new to this so I hope I am doing things right. If I am
in error, please let me know what I must do to correct

I got interested in lapidary about 20 years ago when I got
stationed in New Mexico for 9 years. There wasn't much else
to do there. My interest include just about anything to do
with lapidary although I am not very interested in fossils.

Mostly I do cabbing, I like to cut and polish cabs. I have
several slab saws including an 18 inch Lortone saw, and a
Genie grinding machine. I have a friend with a few carved
pieces he would like to sell but he doesn't have access to
the Internet so I told him I would offer them in this forum
if that is permissible.

I read your rules but as I said I am new to this and am
unsure of how to go about it. Your assistance would be
greatly appreciated.

Thank You.

David Blackman
Welcome David, and relax about screwing up. If you do,
nothing bad can happen, cause we don't flame anyone on this
list and everyone is polite, kind and helpful - or at least
I hope so! (smile) Hope you enjoy the Digest. hale

Subject: BIO: Mining Center Peru


We are New Members. We are from PERU. Any news you need
about Peru or South America please let us know it and we
will answer you a.s.a.p.

PINK OPAL, YELLOW OPAL and other Peruvian and South American

fax: 51-1- 4498492

Subject: BIO: Cortney Mayle


I'm a young (amateur) jeweler from Pittsburgh, PA with a
strong interest in learning how to do my own lapidary work.
I've recently started to make jewelry on my own after a 2
year hiatus (took classes in high school). I'm focusing on
lost wax casting, with a style that highlights the stones I
use in my work (almost exclusively cabs). I am doing my
best to make pieces which will attract a clientele of cavers
(of which I am one), as well as folks in general.

I look forward to learning a lot from you guys, and
appreciate any help.

Cortney Mayle
< >
Information Science, U of Pittsburgh

Subject: WTB: Calico Agate


I was wondering if anyone had any information on Calico
Agate. I recently received some of the material and I love
it, but someone said it is mined out. Does anyone know the
history of it and where I can find more?

Randy Aue
Estes Park, CO

Subject: WTB: Cabbing Services

I have a bunch of rough stones I want cabbed, and was
wondering if someone would be willing to do this for me at a
reasonable cost (have pity on a poor college student :o) The
material I have includes a large slab of tiger iron, a 200g
lot of small pieces of peridot (about a gram each, I think)
as well as a pound of tumbler stones (typical mixture of
tigers eye, agates, a bit of quartz).

Cortney Mayle
< >
Information Science, U of Pittsburgh
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