LAPIDARY DIGEST
Administered by Hale Sweeny (hale2@mindspring.com)
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This list digest contains the following message subjects:

1. LapDigest News for Issue No. 91 -
2. SPECIAL: The Kitchen-Table Opal Triplet
3. SPECIAL: Notes on Making Doublets & Triplets
4. SPECIAL: Buying Triplet Opal Material
5. SPECIAL: Clear Synthetic Spinel Caps
6. SPECIAL: Glueing Doublets and Triplets


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<MSG1>

Subject: LapDigest News for Issue No. 91 -

This issue and the next two are devoted to the making of
doublets and triplets.We usually think of them as being made
from opal, and that will be the central focus here, but they
may be made from other materials such as Abalone shell, and
ammonite. (A whole issue devoted to making ammonite jewelry
will published in the next month or so.)

The notes you are and have been submitting the past few days
are being saved and will be published after this and the next
two issues.

Please keep sending in queries so there will be something we
can start up with again, after these three issues!

In addition to the papers below, Paul Downing has a well
written Chapter 12 in his book: OPAL CUTTING MADE EASY
devoted to making doublets and triplets.

Do try to make some triplets. They are not hard, especially
using the simple hand methods described in the first paper
below. Enjoy Lapidary!! Have fun!!

hale
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Subject: SPECIAL: The Kitchen-Table Opal Triplet
by Hans Durstling


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The first version of this paper appeared in Eclectic Lapidary
last year; Hans Durstling revised and rewrote it expressly
for publication here - no graphics! It appears first in this
issue as it gives methods for making triplets by hand, and
his descriptions provide a foundation to the other papers.

Hans Durstling has been a member of the list since June,
almost from the beginning. He has contributed several
articles to LapDigest, the most recent one about retensioning
saw blades. He is a freelance writer, jewellery maker and
stone cutter living in Moncton, New Brunswick, Canada, near
the Bay of Fundy. His stories, reviews and commentaries have
appeared in Canadian Geographic Magazine, The European,
Toronto Globe & Mail, Canadian Mineralogist, Mineralienwelt,
Rock & Gem and many others. He now works primarily in
corporate and industrial writing explaining complicated
scientific and technical products and processes to layman
readers, and writing and narrating corporate and technical
videos. A considerable portion of his time is taken up with
the constant battle to keep minerals and gems ("the hobby
that got out of control") from taking over entirely.

Hans can be reached at sinico@nbnet.nb.ca.
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An opal triplet is a composite stone made up of three
layers. On the bottom is the backing layer, of black basalt
or other dark stone, or perhaps of black architectural glass.
In a pinch, I've even used dark welder's shield glass. In the
middle of the sandwich a very thin layer of precious opal,
which in turn is covered over by a protective "dome" of clear
quartz.

Unfortunately a hint of stigma attaches to the "triplet"
designation, a spillover from other precious stones where
making a composite is usually an outright fraud. It's
amplified by a gap in understanding between the goldsmiths
and the stone cutters. The goldsmith works his material in
quite a different way. He can shape it and alter it almost
infinitely. He doesn't have to contend with features that
can't be changed, and so will tend to expect, even if
unconsciously, a similar range of possibilities from the
stone cutter. Also, a goldsmith, while he may be stone-savvy,
probably is so to a limited extent. He will have heard of a
variety of treatments, triplets, doublets, foilings, dyeings
and such designed to imitate high value precious stones, and
so will regard the word "triplet" with mistrust in any
context. An opal triplet however imitates nothing.

Why make a triplet? There are two reasons. First, in opal
you or I can afford, the colour often runs through the stone
only in a thin layer, most of the stone being a bland white
or cream coloured "potch." If you could grind away all the
useless part of the stone you'd end up with a wafer of colour
like a single cornflake and often not much thicker. And what
can you do with that except break it? Second, play of colour
is opal's distinguishing feature, and opal in a triplet shows
its colours to their very best advantage. In fact, in some
cases, the colour of a stone which is sufficiently thick that
it could be cut as a solid stone is dramatically improved
further when it is cut as a triplet. Bear in mind that you
are not putting in any colours that are not already there.
What you are doing is carefully working the stone to extract
its maximum beauty. And that, after all, is what gem cutting
is all about. There's nothing counterfeit about these
purposes. As far as I am aware only for opal is making a
triplet a traditional and fully legitimate technique. Perhaps
for ammolite also, but that's so recent a stone on the market
that one can hardly speak of a cutting tradition.

Right then. After this much philosophy let's get some dirt
under the fingernails. The nice thing about making triplets
is that if you have opal rough and a few basic tools, you can
do the whole thing on the kitchen table. If you're really
skilled at improvising you don't need a saw, or even a
cabbing machine. But both help, and we will be using them.

Usually the opal rough you buy in a small bottle for, say,
in the 30$ an ounce range consists of chips of white opal
somewhere between a dime and a quarter in diametre - often
smaller, seldom larger. These are chips that a professional
cutter refused, there not being enough saleable, good colour
material in them to adequately compensate him for the time it
would take him to cut them. The key here is "adequately
compensate". There may well be colour in the rough. It may
well make an excellent stone when the colour is carefully
worked free. But if a professional cutter is going to spend
three hours doing that, he needs to be sure the result is
going bring a hundred dollars or two. As amateurs, we don't
have that problem. We do it because we enjoy it. Thus our
affordable rough opal is not necessarily trash, but is
necessarily time-consuming.

It's that colour seam that you want to isolate in the form
of a thin wafer. There are lots of ways of doing it. You can
grind down to the seam from the top, or you can grind away
the bottom, or, if you have a thin slicer saw, you can saw
away the potch on both sides. But for the purposes of this
story, we're hand grinding on the kitchen table.

Onto the kitchen table a newspaper is spread out, and on
that goes a piece of plate glass, say one foot long by 6
inches wide to give a good working surface. The plate glass
will be the underlay on which the grinding is done. Glass
1/4" thick is good, being thick enough that it doesn't bend
much and is not so fragile.

Put down on the glass just a small knife tip of 220 grit
abrasive, moisten that, and, holding the opal between your
fingers, rub it round and round and back in forth in the grit
slurry. At first the opal chip will bind up a bit, catch and
dig into the glass, but once its rough edges have been
removed it'll grind quite readily. You'll be surprised how
fast it wears away. Check periodically to see how close
you're coming to the colour layer. Once you hit the colour,
stop grinding. Now you've got to think and make decisions.

Check the colour layer. The aim is to develop the biggest
possible area of colour which of course gets you the biggest
opal wafer and thus also the biggest finished stone. If the
colour layer is more or less flat, you're in luck. You can
get a good area of colour. If it runs through the stone in a
wave or saddle shape, then you have problems. Imagine a
colour layer in an "S" shape. You'll have to look carefully
and consider which "leg" of the S you'll want to expose to
give you the biggest area of colour. If the colour layer is
like a "U", do the sides or the bottom present the bigger
useable areas? Picture it as a bent ham sandwich. Your
challenge is to grind away away the bread to expose a maximum
area of ham.

Once you've got the maximum extent of colour exposed, the
next step is to cement on either the top or the bottom, the
top being a wafer of clear quartz, the bottom being dark
basalt or black glass. I like to cement on the bottom, the
basalt, first, because that way when you continue the hand
grinding to remove the excess on the top side of the stone
you can watch as the colour layer develops and the colours
intensify (or weaken, in which case you grind no further) as
you grind closer and closer to the basalt.

Initially I was afraid I'd grind away too much of the
colour, so I'd leave the wafer in the middle of my triplets
fairly thick. The trouble with that is, with the opal we
hobbyists commonly use, the thicker the opal layer is the
more of the white base colour stays in the wafer. The result
is a triplet in which the opal colours appear as if through a
cloudy, milky veil. The thinner the colour layer on the other
hand, the more dramatically the colours stand out against the
black backing. So, after a bit of experimentation perhaps,
don't be afraid to grind the opal down to a very thin layer
indeed, in some cases almost as thin as a sheet of paper.
Cementing the opal to the black backing first allows you to
check the progress of this effect as you work.

Just to recap, the procedure I use is to grind the opal
chip on the glass until until the maximum area of colour is
exposed. That side of the chip is then cemented to the black
backing. The backing also should first be ground flat on the
glass sheet grinding lap. You don't need to go any finer than
220 grit, and that's still rough enough to give a good
gripping surface for the epoxy.

For cementing I use epoxy 330. It dries clear and strong.
Prior to applying epoxy the surfaces to be glued should be
cleaned with acetone, since finger grease harms the bond.
Bubbles are a constant hazard, though, and here I've found
warming the stone, the quartz top and the backing helps make
the epoxy thin and runny. I use an old restaurant coffee
warmer upon the heating element of which I lay a slab of
three quarter inch granite. It takes a while to warm up, but
holds heat nicely. A heat lamp works well also. The chip
should be lowered with tweezers onto the backing at an angle,
and then gradually eased down flat, somewhat like laying a
book down slowly on the table. This procedure helps prevent
bubbles. It's also easier said than done.

In fact, working with epoxy on an opal chip half the size
of a dime is not a lot of fun. No matter how careful you are,
the epoxy gets on your fingers, your tools, and the working
area. Epoxy covered tweezer tips make manipulating the opal
chip a procedure to be accompanied by a background music of
curses. Keep a bottle of rubbing alcohol handy to unstick
fingers and tools.

The glue doesn't need to be epoxy. Canada Balsam is used,
as are stick shellac and even dop wax. You'd think the dop
wax would leave a telltale colour, but the sticking layer is
so thin it's transparent. Each of these adhesives is made to
flow by heat. Thus a triplet made in this way is more
susceptible to coming apart if the piece of jewellery it ends
up in is subjected to undue heat. Also, Canada Balsam and
stick shellac are more difficult to come by than epoxy.

Once you get confident you can glue up a number of opal
chips on the same backing, and then grind them all down in
one go. This saves time but lessens the control you have over
each individual stone, since all will be ground to the same
thickness.

Assuming you're still working with a single opal chip,
once it's ground down to its final thickness the wafer of
clear quartz is cemented on top in the same way as described
above. Clothespins and bobby pins help hold things in
position, gentle heat from a heat lamp speeds curing. What
you have now is a sandwich: black backing on the bottom, the
thin layer of opal in the middle, a slice of clear quartz on
top.

The finished sandwich is now treated as any normal
cabochon would be, shaped, domed and polished. I always go
for maximum area of opal, which means that the finished
cabochon stones are not necessarily oval, since in order to
get that standard oval shape I'd have to sacrifice some of
the opal. After all that work putting it together, it seems
a shame to grind it off again. Grind the black backing layer
as thin as you can, 1/32nd inch is more than sufficient.
Otherwise, with too much backing, you get too thick a stone.
The stone should be cut with a comparatively low profile. Too
high a dome acts as a magnifier and makes the stone look
unnatural, and also, looked at from the side, the high dome
is transparent. The finished stone is bezel set, with the
bezel covering the joint.

And that's all there is to it. The result is a triplet
with brilliant colour flash and that is no less "real" than
any other stone. However, it's not uncommon for such a stone
to be sold to an unsuspecting customer simply as "opal"
without any elaboration. That indeed is unethical. A triplet
should always be identified as such.

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<MSG3>

Subject: SPECIAL: Notes on Making Doublets & Triplets

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I have known Goeff Haughton for several years, as we are both
members of the same club. In real life, he is an immunologist
with UNC. His wife, Christine,is Finnish, and they frequently
visit her home in Finland. Goeff always seems to bring back
beautiful pieces of Spectrolite rough - right from the mines.
He is a meticulous craftsman, and all his gems are finished as
jewelry. I know this about him: he knows lapidary.

His address is: ghaughto@med.unc.edu
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Opal triplets are usually made to conserve valuable opal. By
using paper-thin slices of opal between a backing of potch or
some black material and a clear cap, a small amount of opal
can be made to go a long way, and relatively inexpensive
stones can be produced. There are other reasons, but this is
the most common one.

Generally, the opal used in triplets is extremely thin and
fragile; it is usually cemented to the backing material right
after being cut with specialized equipment. I think fine wire
saws are used, but other folk may be able to provide more
details. You would cement the cap on to the backed opal and
then cut the whole sandwich down to the size of the cap.
Usually, the base is tapered down slightly so as to place the
opal slice at the widest part of the stone.

I rarely make triplets. However, I do make doublets.

There are a number of reasons for making doublets and, to
some extent, the technique employed varies with the purpose
intended. Three possible purposes would be:-

1. To add bulk to a stone that would otherwise be too thin to
use, as with some pieces of opaque opal. In this case, the
best backing material is opal potch of the same body color as
the precious opal to be backed. This is easy to come by,
since it makes up the majority of the cheapest grades of
opal, sold by the pound as "practice opal" or "beginner opal".

2. To protect the surface of an attractive but fragile or
soft stone. I have treated abalone shell and ammolite in this
way, but there is a host of other stones that can be used.
In this case, the idea is to put a quartz cap on. In general,
the cap should be quite thin and low domed unless you really
want the magnifying effect of a thicker quartz lens.

3. To provide a dark background for a transparent or
translucent opal, so that the play of color shows more
brightly. I have used this approach to good effect when
working with Brazilian opal, the best of which is quite
transparent. I use obsidian for the backing and vary the
effect by use of opaque black, translucent or rainbow
obsidian. Basinite or onyx can also be used.

Some of the general guidelines to follow in cementing any two
stones together, whether for a doublet or a triplet are:-

1. The surfaces to be joined should be absolutely flat, but
not polished. I usually use a 260 grit diamond disk; this
leaves the surface sufficiently rough for the glue to bite.

2. The surfaces must be clean and absolutely free of oil. To
be safe, I usually wash them with hot water and dish washing
detergent, followed by alcohol and then followed by acetone.

3. The choice of adhesive is important. I have tried several
and have settled on Devcon "2-Ton" clear epoxy. Its
advantages are that it is relatively heat resistant so that I
can dop the stone with wax and it is waterproof so that the
stone will not fall apart in a rainstorm or in the shower. It
is also space filling, so that it forgives me if the surfaces
are not quite optically flat. I don't know that this is the
best possible glue and would welcome suggestions.

4. Avoid bubbles in the glue. This means that one must be
very careful in mixing the two components of the epoxy
cement. If bubbles are left in the joint, they will show but
if the epoxy is not mixed thoroughly, it won't work.

5. Don't work with the doublet until the glue has really
hardened. Give it at least two days and keep it warm. Epoxy
cement will not cure properly in the cold.

When working with Brazilian opal, I cement several pieces
onto a slab of obsidian and put it in a warm place for a
couple of days. I then cut it up with a trim saw, dop the
pieces and carefully grind the top surface of the opal to see
what I have got. From then on it is just like cutting any
opal. The critical points are orienting the opal before you
start and grinding the flat surface until the color just
shows. It takes practice.


Non commercial republication permitted.
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Subject: SPECIAL: Buying Triplet Opal Material


Buying material for triplets isn't difficult; tell the opal
dealer that you want to buy opal for triplets, and tell the
dealer the size of triplets you wish to make and the colors
you want (mostly red or green/orange). If you do not have a
saw, ask for thin material, or ask whether they will slice
them for you.

Ask also for backing material. Here in the NW we have a lot
of Basenite that cuts easily and, when cut, is quite black.
It is found up in the mountains, like Green Mountian up north
from here.

I did sell kits with all the material that you needed, all
sliced up. Unfortunately, I can't get the quartz caps now, so
have stopped making up kits.

Darlene Munroe
dmunroe@sprynet.com
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Subject: SPECIAL: Clear Synthetic Spinel Caps


Now might be as good a time as any to mention the fact that
some years ago, there were doublet caps sold which were made
from clear synthetic spinel. They were nicely domed and cut
to standard sizes. All that one need do was cement the caps
to the selected doublet material and grind to the shape of
the doublet cap. The synthetic spinel being much harder than
quartz seemed to make a much better finished product. We
still have some of these left kicking around somewhere.

Regards,
John
johnpat@ix.netcom.com

Non-commercial publication permitted.
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Subject: SPECIAL: Glueing Doublets and Triplets


Dear Hale,
I have been receiving your news letter for a while now.

I am pretty new to the lapidary field , and it has been a
great help to me. Youe articles about new and different glues
are wonderful. I make a lot of opal doublets and triplets and
after trying the uv glue I will have a hard time going back
to epoxy. I glued two microscope slides together and soaked
them in water, alcohol, lacquer thinner, and acetone. So far
there is no sign of them coming unglued. I love it.

I am looking for information about making jewelry from my
gems; would you know of any newletters which cover this
subject?

Keep up the good work . Have a happy holidays and thank you
very much.

Michael Sielaff
Mijo730@aol.com
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(Ed. Note: The glue Michael refers to is a Loctite Crystal
Clear Glass Adhesive 81190 or CGA-1, sold under the DURO
label. hale)
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