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Associate Editors: Geo. Butts, JR Shroeder, Steve Henegar,
Margaret Malm, and Sam Todaro

This list digest contains the following message subjects:

1. LapDigest News for Issue No 273 - Mon 5/1/2000
2. NEW: Making and Using Laps with Diamond Compounds
3. NEW: Need Substrate for Diamond Grit
4. NEW: Cabber Tape
5. NEW: Widening the Kerf on a Diamond Saw Blade
6. NEW: Williamsite
7. NEW: Silicon Carbide Grinding Wheel
8. NEW: Stabilizing Turquoise
9. NEW: Filling the Gap - Blade to Table on Trim Saw
10. RE: Protecting Druzy Materials
11. RE: Working & Polishing Koroit Nuts
12. RE: Working & Polishing Koroit Nuts
13. RE: Diamond Wheel Speeds
14. RE: Expanding Drum Problem
15. RE: FS: Ruby in Zoisite
16. WTB: 18" Slab Saw


Subject: LapDigest News for Issue No 273 - Mon 5/1/2000

As you know, I went to Wildacres and took a week-long class
in Glass Fusing. It was great! First time in a long time
that I have taken a class in something about which I knew
absolutely nothing!! And the first time I have worked with
hot glass since I studied cloisonné years ago!

When I returned, I found over 500 new messages and 30 of
these messages in the LapDigest file for the next issue,
about twice as many as we normally use. So, sorry, guys,
but some will not be used (my decision), and some will be
kept as fill-in on upcoming issues. So if you don't see
your letter here or in the next two or three issues,
you'll know what happened.

Gotta get back to the CONTEST with rules and all that. For
those of you who just joined, the CONTEST is for the design
of a cabbing machine to make at home. Thus it must have
most parts that are available to everyone - that is, catalog
items. Will get to it and post rules very soon. Lots of
prizes (mainly GREAT cabbing rough) and $100 to help the
winner actually build a working model.

I had finished the Digest and was ready to send it out when
the power failed and my unsaved copy went pffft!! It was
relatively easy to redo it a second time -- all decisions
had been made. But don't you just kick yourself when that
happens, and you KNOW you should have saved it!!

The weather here has been magnificent! If you go out to
play, please be careful, and take care of those you love.
We need 'em.


Subject: NEW: Making and Using Laps with Diamond Compounds

I love diamond compounds. They are rather cheap if you
consider how long they last, and they can be used to make
anything into a lap. To make them, you have to charge up
something with the diamond to lap your stones against.

They sell peel and stick canvas or leather pads coated with
a resin to make the diamonds stick better. These can be
affixed to a plate, glass, tile, square of wood, etc. Then
clearly mark it with the mesh size of the diamond compound.

Another very easy to find and cheap lap board for compound
is a small cutting board made of wood. These are normally
made from good hardwoods, are unfinished, and come in all
kinds of shapes. You should get one for each grit you use,
example, the average diamond compound 'kit' comes with 6
grits and 1 bottle of extender so you need 6 lap boards.
The plastic or resin boards might work well, but a lot of
them have a bit of texture to them that will make things

Charging your laps is rather easy. Put a 1/4" dollop of
compound on the face of your stone (Hale's note: a polished
piece of agate, for example), and rub it firmly around
your lap. I normally start dead center of my lapping
surface, and work in circles around the area. When you work
in the first dab well, add another, and keep going. I
normally add 2 or 3 dabs then add one or two drops of
extender. Make sure you keep all the compound on the pad,
wipe off excess from the sides, put it back to the middle,
and rub it in as well.

Once you have done this process for a handful of stones,
the lap will be charged well and you can work with just a
drop of extender fluid, adding in more compound as you

I find that a set of hardwood laps (mine are maple cheese
boards, little cutting boards with handles and a groove
around the outside for a lid to sit on), once charged up
with 1 gram each of diamond compound, will last me a long
long time. Just make sure you keep them dry and separated.

Its best to build yourself a storage unit for your laps. I
opted for the cheap and easy method, simply going to the
office supply store and finding stacking document trays
made of plastic. The kind you use for the old Inbox/Outbox.
I removed the standoff legs, and glued them together.
They were designed to stack together anyhow, so the finished
product looks good. I then just slide in one of my good old
maple cutting boards into its one little hole. To make sure
I'm not bothered buy the odd diamond dust falling, I always
sort the laps so the lowest grits are at the bottom. If the
finer grits fall down, they dont matter so much as if the
heavy grits fell onto the fine laps.

Should your laps become contaminated, use some turpentine
to clean off your lap well, and sand with a very fine grit
paper. Then just start all over again with another syringe
of compound. If you make sure you store each lap before
fetching another and wash everything well with soap and a
toothbrush (make sure you get the dop to!) between laps,
everything should last for ages. By the time you get a few
grams of diamond compound rubbed in, they will become close
old friends whipping you through stones faster then you
dreamed possible.

James: Thanks. I hope you will write and tell us where to
buy the leather or canvas resin-coated pads. And where we
can buy diamond grit inexpensively. I also hope you will
write a continuation describing the technique for using
these diamond hand laps. (That is why I added 'Using' to
the name of this thread.) hale

Subject: NEW: Need Substrate for Diamond Grit

Hi Folks,

I've just recuperated quite a few grams (yes, grams not
carats!) of diamond grit from a number of sintered metal
wheels I got from a friend in the optical business. I won't
describe the process in detail here save to say that it took
acids and patience and prudence.

The result so far (with quite a few more wheels remaining to
be treated) is about 4-5 grams of beautiful sparkly yellow
blocky diamond "soccer balls" which I would estimate to be
about 80/100 grit, and, from the finer wheel, about half
that amount in what looks to be about 400/600 grit.

The coarse diamond, charged into a home-made 6" bronze disc
and run on the CabMate, cuts with wonderful fierce

But I haven't charged the fine diamond into a wheel of any
kind yet, because that's where I'd like to sound out list
members for advice and suggestions.

Cutting a cab with fine grit on a metal lap leaves flat
spirals around the stone, since, unlike rubber or leather,
metal is without "give" to accommodate itself to the
curvature of the cab.

While these flat fine-grind spirals can be erased in
subsequent sanding, it seems pointless to put them there in
the first place if it can be avoided. So that's my question.
What should I use as a moderately flexible substrate which
will carry 400-600 grit diamond?

Some desirable characteristics of this substrate would be

- To carry the diamond grit fairly reliably without flinging
it all over the place (I do faceting in the same room);

- To carry it such that it retains its cutting efficiency
(i.e. where it won't sink in under the surface of the
substrate) and be lost for cutting that way;

- And above all, to be flexible enough to help form, and
conform to, the rounded surface of a stone.

At the moment I'm leaning toward trying a grooved maple
wheel, since maple is easy to get and easy to form with home
tools. It doesn't have a heck of a lot of flex, but grooving
should help yield rounded surfaces. I sometimes use maple
for polishing with grease-based 14,000 diamond, and for
pre-polishing with 2,500 grit. But I have no first hand
experience whether maple will hold grit as coarse as 400
- 600, and what carrier (wax, grease, olive oil, crazy
glue???) would be best to use.

How about other wheel materials? Plexiglas? Some kind of
synthetic leather or other synthetic material? Hard felt
(unlikely??) Any other kind of wood? Any other kind of

Any and all suggestions gratefully received; first hand
experiences even moreso.

Cheers & thanks,
Hans Durstling
Moncton, Canada

Subject: NEW: Cabber Tape

I have a Lortone SA-8 that was purchased in 1974; one side
has an expandable drum (no problems) and the other side has
a SiC wheel. I just purchased a GY-ROC CABBER from
Kinglsey-North so that I could make better shaped cabs than
I can by hand.

The Cabber came with a roll of GY-ROC double-faced cabber
tape to attach the stone to the cabber. Sometimes (rarely)
the stone stays on the cabber, and I can go from the SiC
wheel to the polish on the expandable drum with one
application of tape. The rest of the time I need to apply
the tape to the stone many times just on the SiC before I
ever get to the drum.

1. Does this tape dry out and loose its stickiness?
2. Where can I get more tape that may be newer?

Thanks for all the help

I wrote to Kingsley North, describing your problem and asked
for a suggested solution. I'll print it when I get it. hale

Subject: NEW: Widening the Kerf on a Diamond Saw Blade

I am told you can lay the edge of a file on a diamond blade
and strike it with a hammer all the way around the blade to
widen the kerf and make cutting easier. Is this advisable?
If so, is there a better way to do it? Any other advice?

David Calame, Sr.

Subject: NEW: Williamsite

Could anyone tell me about Williamsite? I've only found
one piece in an auction. It looks like jade with some black
specks running through it.

Thank you

Irene Corbett
Irene: I searched my database of minerals and found one
named 'Willemseite', but none named Williamsite. Its
characteristics are:

Mineral: Willemseite
Formula: (Ni,Mg)3Si4O10(OH)2
System: Monoclinic
Color: Light green
Hardness: 2 2
Density: 3.31 3.31
Cleavages: 1
Cleavage Desc: {001} perfect
Habit: Massive, fine-grained

Now Williamsite may be a rock name and not a mineral name.
Do you think it has a hardness of about 2? (This means that
if your Williamsite will scratch Gypsum but not Calcite,
then it has the same hardness as Willemseite, but if it
scratches calcite, then it is harder than Willemseite.)Hope
this helps. hale

Subject: NEW: Silicon Carbide Grinding Wheel

Is the grinding wheel found on common bench grinders the
same kind of silicon carbide grinding wheel used on cabbing

David Calame, Sr.

Subject: NEW: Stabilizing Turquoise


I wonder if any Lapidary Digest member(s) can share their
knowledge of stabilizing turquoise. This is my latest quest.
I want to learn to stabilize my own turquoise. I realize
that some stabilizing processes have been kept secret for
generations, but I would be most grateful if anyone on the
list would share their knowledge.


Jed: Suggest you start with a search of the literature. I
did a search of titles of articles in Rock & Gem
( and found the following items, which
may or may not have what you need:
Suggest you search Lapidary Journal using their Index book.
Also hope someone here can add to your knowledge. hale

Subject: NEW: Filling the Gap - Blade to Table on Trim Saw

My Lortone trim saw had a gap in the table that was really
wide. This made cutting thin slices difficult. So, I made
a new table for my trim saw to close this gap. Here's how:

I simply took a piece of Plexiglas, cut it to fit the size
of the table on my trim saw. Then I used a general purpose
diamond blade (wider cut) on the trim saw to cut a slice
down the middle of the Plexiglas, not all the way through,
positioned so the slit would exactly fit over the blade. And
yes, its a wet saw, it cuts plexi just fine :)

The end result is a plate of Plexiglas that fits snugly
down on top of the table on my saw, the blade sticks through
the slot cut with the .025" blade. Then I mount up a super
thin blade, like .018 or .015". Slicing up a bit of opal
is easy now, the finished slices can be supported on both
sides, and don't end up dropping into the coolant tank.
Remember that a thin blade can and will cut you.


Subject: RE: Protecting Druzy Materials

I have been cutting druzy materials for 5 years (not long
in lapidary time), including azurite, variscite, malachite,
vanadianite, cobaltian calcite, rainbow hematite,
psilomelane, rhodochrosite, quartz and others.

I use an "all-in-one" unit and cut small pieces used in
earrings, pins and pendants with water as a coolant. The
most difficult piece I had to clean was a piece of white
quartz cut with Almag (by someone else) and I had to use
mineral spirits to get the residue out. Prior to that I
tried Dawn detergent and toothbrush, alcohol, Spray'n Wash,
ultrasonic cleaner, ammonia, steam cleaner and acetone.
Quartz will take that abuse, but all the others except
psilomelane will not.

Solvent to dissolve lacquer will ruin azurite, malachite,
vanadianite, etc. I do not use anything to protect the
druzy because cleaning anything off the crystals is more
trouble than cleaning them. I use the ultrasonic and
steam cleaner on quartz, and soap or detergent on the

Just remember to dry them upside down.

Hope this helps.
Robin Pascal
Houston, Texas

Subject: RE: Working & Polishing Koroit Nuts

A Koroit nut is a chunk of ironstone matrix that’s may
contain opal in various degrees. Some very rare nuts are
solid opal inside, others have seams of fire webbing around
everyplace, and finally some are nothing but ironstone.

Working with Koroit makes a mess. The soft stuff the nut
is covered and mixed with just turns to mud as you work it.
Have plenty of water on hand and wash often or you will
miss the fire.

I normally slice each nut right down the middle first. If
the piece is already cut in half, I'll wash it carefully,
wet it well, spend sometime in a strong light source
(sitting on the porch drinking tea in the sun), and look for
indicators of fire and opal. If you find a seam that’s nice
and flat, you can nibble it out, grind down to the seam on
one side, glue it up to a solid bit of ironstone lapped
flat, and then grind down the other side.

Just keep nibbling at the nut, slabbing off thin bits,
grind away layers, etc, until your quite sure you have found
all the usable fire.

One of the coolest things about Koroit is the picture opal
aspect. Some pieces will have very fine seams of fire
shooting about the nodule. When slabbed and cabbed this
stuff can form spiffy pictures in the finished stone, drawn
in veins of opal.


Subject: RE: Working & Polishing Koroit Nuts

Hi, "Rockgrinder" and Hale:

I've worked with these, a few times, and may be able to help
out, a bit. For starters, a little bit of a "definition", to
whatever degree that's possible...

Koroit nuts are concretions of Opal and Ironstone, much like
their neighbors in Yowah. The primary differences I've noted,
between the two, are in the sizes of the voids replaced by
Opal: the Koroit Nuts' voids seem to be smaller, or more
filament-like, than those from Yowah. Put another way,
Yowah's Opal seams more often resemble gnarled meshes of
parachute cord, mixed in with the Ironstone, while Koroit's
verge on dental floss or monofilament fishing-line.

Another difference between the two has to do with the
Ironstone, itself: in the case of Yowah Nuts, I've noted a
tendency of the concretions to have a more uniformly dense
center (opalized center with dense Ironstone, surrounded by
an ever less-dense "rind"); with the Koroit Nuts, you'll
often find pockets of almost powdery, ochre-colored Limonite
clay, as well as dense pockets of opalized Ironstone,
seemingly without rhyme or reason.

As for how to approach the stuff, my way has always been to
warm the stone on a dopping stove, then mix enough Opticon
to completely cover it/them, in a small, clear plastic
party tumbler, then *gently* (so as not to generate
unnecessary air bubbles) insert the sliced "nut(s)" into the
mixture with a hemostat, and place outside, to allow it to
harden. When it has, use either your trim saw or a jeweler's
saw to remove the section containing the rough, and dop and
cab it, progressively cutting down through the hardened
Opticon to the stone, itself. In this way, you'll be able to
finish the piece, in it's entirety, without having to curse
at those undercutting pockets of powder, in the process!

Glad To help out!

Best Regards,
Doug Turet
Doug and James: Karoit nuts don't have 'landmarks' to help
orient the nuts, do they? If they are oval in cross section
should you cut across the thick direction or across the thin
direction? Any help from their outside appearance? hale

Subject: RE: Diamond Wheel Speeds

In reply to the question about diamond wheel speed, I can
quote the info on an industrial wheel I have. It is labeled
"Precision," serial no. 18-04553-000. The diamond content
is MD180-S3 BD-1/16-66. The max. RPM is 4200 for a 6" dia.
wheel. Two things to keep in mind are that this is a solid
aluminum wheel built for industrial use and it has 4 ,1/4"
machine screws to hold it in place. Hope this helps a bit.

Good luck,


Subject: RE: Expanding Drum Problem

In a message dated 3/19/00 9:47:28 AM Eastern Standard Time,
Hale writes:

<<Thanks all of you who have listed your expandable drums
and describing your experiences with them. If you have not
done this yet, please send me a note telling me what drums
you have (makes, sizes) and their ages. Thanks, guys.>>

Sorry, I know that this is really out of date. I'm waaay
behind on email. I have an expandable drum, 8x3 of the
angled slot type. I think it is made by Star diamond,
Beacon Star or whatever that company is. It is at least 20
years old, purchased used, and has always been so tight
that it takes several minutes to work a belt on or off.

I've never found a belt that would just slip on it,
especially when it is wet. I got some feedback from folks
on the Rockhounds list about 4 years ago that this is a
pretty common problem, so I've just put up with it.

Ben Brauchler
Thanks, Ben. You have been added to the inventory of drum
owners. For those who have just joined, the problem is that
too many belt/drum combinations are so tight that getting
the belt on or off is a big struggle. The belts are made by
one group and the drums by another and I don't think they
have ever effectively communicated with one another -- if
they had, this problem would not be so prevalent! What I
wanted to do was to get a list of drum owners who have had
and who have not had problems, and ask them to measure the
circumference of their drums using a procedure we will
supply. Then we will use statistics to characterize the
drum diameters.

If you haven't sent in information on your drum, please do
so as soon as possible. I want: MAKE, SIZE, and the age of
your drum(s). Thanks! hale

Subject: RE: FS: Ruby in Zoisite

Hey Carl (

Sorry to be the bearer of bad news, but the Zoisite in
question, in this rough, is actually Chrome Zoisite, a
coarsely-grained metamorphic rock (similar in hardness,
durability and texture to the white limestone chips you may
have seen in some East Coast office building walkways),
which consists primarily of blackish-green Chromite flecks,
Biotite Mica and the aforementioned Zoisite.

Although I haven't tried to do so, I have the sneaking
suspicion that heat-treating this stuff would merely
reduce it to sand! (Then again, that might be an easy way
to release its inherent Ruby crystals, many of which are
solid enough to cab or carve...)

Hope I'll be able to offer better news and/or insights,
next time!

All The Best,
Doug Turet

Subject: WTB: 18" Slab Saw

I have reached the point where my 8 inch wet saw is just
too tiny for what I need. I would like to bite the bullet
and get something BIG. I have looked and I can't afford to
buy a new 24 inch saw. I can get new blades and I have
electric motors and the ability to wire up controls. If
anyone has an 18 inch or larger saw that they are no longer
using and want to sell or trade drop me an e-mail at

Toby Thomas
Southlake, Texas
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