I have seen mention of Opticon on Orchid previously, but I don’t
know much about the product, or its use in the trade. Someone has
brought it an old piece of jewelry, and the center is a large, flat
cabochon (38mm X 27mm X 5mm thick) of highly included peridot with a
number of cracks in it. Would Opticon treatment do anything to
minimize the obvious cracks, or is there another way of dealing with
it (besides putting it in the trash, that is) and, is there an
Orchidian with experience with Opticon who could do this or tell me
how to do it myself? Thank you, Davod Barzilay, Lord of the Rings

Davod - An alternative to Opticon is mixing Epoxy330 (another
product from the same manufacturer as Opticon) in the normal
fashion, and then diluting it immediately with an equal amount of
acetone. If possible the stone should be thoroughly de-greased,
washed, and dried; then warmed to 150 degrees F (I have a toaster
oven set aside for just such use). After all these steps is when you
do the Epoxy/acetone mixture, and cover the stone generously. When
the mix is set, gently sand the surface down with 600 grit or finer
abrasive paper (wet) and repolish the surface. Opticon works well,
but it takes a great deal longer to accomplish the same end.

Jim Small
Small Wonders

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David: I’ve used Opticon 224 a number of time and can tell you a
little about it. One caveat first–I have never been satisfied with
the results I’ve gotten, so I may not be the best source of

Basically, Opticon is a 2-part epoxy. to use it you:

  1. Clean the stone thoroughly.

  2. Coat the surface with the resin. Alternatively you can immerse the
    stone in a pan of the resin.

  3. Put it in an oven at 150 degrees F for 1 hour, or until the
    fractures disappear.

  4. Wipe the excess resin from the surface.

  5. Apply the hardener to the surface

  6. Wait a bit and remove the excess hardener from the surface.

The manufacturer claims it will fill pits on the surface. In my
experience, it fills pits as poorly as it fills cracks. I have had
disappointing results with a range of stones including amethyst,
Australian white opal, Peruvian blue opal, nephrite, and sugelite. I
have spoken to a few other lapidaries who have had similarly
disappointing results. Perhaps you’ll get better results. If you (or
any other Orchidian) do get good results, please let me know how you
accomplish them and with what stones. Good luck!

Michael Conlin

and it in the resin for results I was

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Hi David,

Opticon is similar to a 2 part epoxy in that it uses a sealer and a
cataylst to achieve curing. The general procedure is to soak the
item in question in warm Opticon (150=BA) with out the catalyst for
about an hour to achieve maximum penetration, after which the item
is wiped off and then treated with a mixture of both the sealer and
catalyst to actually seal the stone. Usually, this is done on rough
before cutting, as any excess must be sanded off, but you can do it
to a finished stone if you are careful to remove all residue. Most
lapidary shops, or Rio Grande, carry the stuff and it may be worth a
try, although it may not improve the stone enough to justify the cost
and time spent treating it. Good luck!

Best regards,

Michael, David, & All, I have used Opticon quite extensively to
stabilize porous materials and to fill in cracks. Opticon does
work, but it is slow and messy. Opticon works best on quartz and
agates because the refractive index of Opticon is close to the
refractive index of quartz and agate. On opaque materials Opticon
readily absorbs into the material. We would clean porous turquoise
by soaking in acetone overnight, then put the turquoise in the
resin of the opticon and let it soak for up to a week. Then we
would put the stones in the hardener and soak them overnight in the
refrigerator freezer. The freezer would slow down the hardening
process and allow the reaction to penetrate the stone. When the
stones were removed from the hardener we would wipe them off and let
them dry. If you forgot them in the refrigerator you ended up with
a lump of cured Opticon with embedded turquoise. This happened more
than once. On a side note I would look into many of the newer resins
that are used to repair windshields on automobiles. I would also
look into many of the products used in space research. About two
years ago I talked with a research scientist at a major aerospace
company about glues to hold on facetting material. He told me he
had developed a material to hold on the tiles of the space shuttle.
I was all set to order some of this material. I asked him how they
got the material to release when they wanted to separate parts. He
said release? Why? It never occurred to him you may want to
separate the parts once you stuck them together. Needless to say as
a facetting adhesive this was not the answer.

Gerry Galarneau

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I have had some bad experiences with Opticon but have also had some
resounding successes. First, I have learned to clean the stone to
be sealed very very well. If it still has saw oil on it, soak it for
several days in detergent and scrub throughly with a brush. Then I
soak it in acetone as well. When it is completely clean, heat the
stone to drive off any moisture.

Sometimes I will seal a slab but experience tells me to cut the
stone through at least the first smoothing (sanding).

I have had limited success in heating the stone in a can on top of a
light bulb oven while it is imersed in the resin. Then I remove it
and place it on a piece of foil. let it cool a bit and then wipe it
off with a clean cloth. I then mix the proper proportion of part a
and part b and cover the entire stone with the mixture. Then, leaving
it on the foil, I either place it back on the light bulb oven or put
my desk lamp down over it for about an hour. The heat seems to cure
the resin more quickly. I remove it and let it cure for at least 24
to 48 hours. There usually is a coating of resin all over the stone
which covers any cracks and/or pits. I then continue with smoothing
and polishing.

I have also used my vacuum casting machine for the operation and
gotten excellent results. The vacuum really removes all air in the
stone and sucks the resin right into the center of the stone. Then
when I add the mixture of part a and part b, I vacuum it again for
about 3 minutes. Result is a very tight and smooth stone. Hope this
helps. Cheers from Don at The Charles Belle Studio in SOFL where it
is raining like crazy and where simple elegance IS fine jewelry.

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One additional trick with the Opticon is to vaccum it prior to
introducing the hardener This will give better penetration of the
cracks. When curing the Opticon with the hardener, use a heat lamp
and get the stone hot enough that it is almost too hot to pick up.
This will result in a bit harder finished product.

There are limitations as to what you can expect. If you have a
clear quartz with a fine crack, the RI of both quartz and the
Opticon are close enough that you will get a fairly good fill. You
will still be able to see the crack with the correct lighting. On
colored, opaque stones, it helps if you mix a coloring agent in to
approximately match the color of the stone you are repairing. You
are still going to be able to see the original cracks.

What Opticon does well though is sealing the cracks and a porous
surface so the polishing steps doesn’t highlight the cracks.

To realy hide the cracks, you need a hi-tech filler. IE to get a
top grade “treatment” on an Emerald, it will cost you between $50
and $100 a carat. This is way out of range for a cab.


To both Gerry Galarneau and to Don at The Charles Belle Studio:

My thanks to both of your for your replies and the very helpful
in them. Your descriptions gave me a very clear
understanding of your approaches. They also gave me renewed hope that
I may be able to get some use out of the Opticon sitting in the back
of my storage cabinet. Thanks for taking the time to share your
approaches with me. Michael Conlin

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Regarding opticon, A friend of mine uses opticon extensively on
fluorite with pyrite (only on the flourite!) and chrysocolla with
azurite, both unstable materials. He mixes the opticon 1 to 10 like
the directions mention, and coated the piece, puts it on wax paper in
an oven he uses ONLY for this purpose and heats it to 200 degrees. He
coats the piece after rough shaping and rough sanding. After curing
it, he does fine sanding and polishing. On very unstable material, I
believe he coats it and cuts it and then coats it again. He does
pieces from a couple ounces to hundreds of pounds.

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soak the repaired stones in opticon at room temperature for 12 - 36
hours and then wipe away all excess opticon. This should not cause
any significant changes to the size or finish of the stones but it
will darken the stones considerably (test an unexposed area by
dabbing on a small amount of opticon to determine whether the color
change is too significant to be acceptable) . The aim of this
treatment is to seal the surface of the stones and hopefully
stabilize the them against any gain or loss of water in the future. 

What is opticon? I have some beautiful stone bowls I would like to
seal against staining - would this work? Alternatively, is there
something similar I could use for sealing that would NOT darken the


Hi Tas. Opticon is the trade name for 100% pure epoxy resin. The
molecules of this material are so small that they can penetrate even
the finest hairline fractures or feathers provided they are open to
the surface (providing a path of entry). This material is great for
that purpose however it is toxic and not suitable for sealing any
containers which will or may be used for food service. I believe
bees wax would be ok for that particular application (i.e. foodsafe)
but might darken the material. A test application on the bottom of
the base would indicate if the color change were undesirable.

Best regards,

I must speak out at this point. I have not seen a word spoken so
far on the subject of opticon being used concerning the hazards of
said product. It is a great product, but it must be mentioned every
time it is discussed, that it must be handled with extreme care.
Really good ventilation, gloves, mask is very desireable, and keep
off your skin if at all possible. This is not a paranoia. Too many
people for many years ignore such warnings, and now have serious
health problems from using products without taking precautions.
Sorry, just had to say something.

Thanks, Mb.

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    What is opticon?  I have some beautiful stone bowls I would
like to seal against staining - would this work?  Alternatively, is
there something similar I could use for sealing that would NOT
darken the stones? 

Opticon is a two-part fracture-sealing resin. It is also clear, and
shouldn’t darken the stone unless the stone in question becomes
darker when wet. If it does, it may also lighten back to its normal
color when dry. It is always best to test a new product on a piece
that doesn’t matter.

James in SoFl