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Treatment to create grey faceted gemstone


#1

Hi,

I would like to create a grey faceted gemstone. Does anyone have any
suggestions, or used books they would like to part with on “cook
book” with specific treatments?

Sincerely,
Terri Sidell,
Terr-if-ick Flair,Inc.


#2

Why not just find some nice grey moonstone and facet it?

LJ


#3

You could use old television screen glass, it’s called TVite in
Australia. It is optically perfect and cuts a beautiful stone, also
very cheap to purchase.

Cheers, Ivan.


#4
Why not just find some nice grey moonstone and facet it? 

The appearance of moonstone is due to optical phenomenon knows as
adularescence. To display it, stone must be cut en cabochon!

Leonid Surpin
www.studioarete.com


#5
You could use old television screen glass, it's called TVite in
Australia. It is optically perfect and cuts a beautiful stone,
also very cheap to purchase. 

Good dispersion, too, because of the lead content. Quite soft, so
not suitable for some applications. However, it won’t really appear
gray, in any reasonable size.

Al Balmer
Sun City, AZ


#6
The appearance of moonstone is due to optical phenomenon knows as
adularescence. To display it, stone must be cut en cabochon! 

If you want a clear “eye” or line, (in those pieces which can give
you that clear an effect), this is correct. However, facetted
moonstone can still display an attractive “flash” of color, even if
it’s not the focused spot or eye that a cab can show. In the more
transparent ones, the combination of that flash and the normal light
reflections from the facetting, can be quite interesting.
Adularescence it’self does not need any particular type of cutting.
Even rough material shows it. The cutting as a cab allows the stone
to act as a lens, focusing the light to a line or spot.

Peter


#7
The appearance of moonstone is due to optical phenomenon knows as
adularescence. To display it, stone must be cut en cabochon! 

This will come as a shock to the faceted moonstones I currently have
in my studio, which have been showing their adularescence
shamefully!

Noel


#8

I have a amethyst that was in a fire. That stone was turned grey from
high heat. A person could heat an amethyst, slowly to a very high
heat and see if it will turn grey. Heat, starting at a low temp and
raise the temp every half hour, until the stone gets to about 1000
degrees, check it and see what the color is and if it still isn’t
grey, heat it to a higher temp or a longer heating time. See if this
works for you.

Veva Bailey


#9
This will come as a shock to the faceted moonstones I currently
have in my studio, which have been showing their adularescence
shamefully! 

Adularescence is commonly confused with other optical phenomena. This
is not surprising. To understand adularescence requires background in
gemstone formation, and we cannot go into that here. There are plenty
of good literature on the subject, so one can educate oneself, if one
wishes.

Leonid Surpin
www.studioarete.com


#10

The key to revealing adularescence in moonstones lies in how the gem
is fashioned. Most moonstones are cabochon cut, which maximizes the
angles at which you can see adularescence, leonid is correct about
that… however, we can see adularescence on faceted moonstones, the
cutter has to orient the adularescence to parallel the gem’s table
facet. FYI leonid

Mark


#11

Ivan,

Thank-you for your suggestion of an old television screen glass.
Colored glass would be a nice option.

Sincerely,
Terri Sidell


#12
Why not just find some nice grey moonstone and facet it? 

That’s a wonderful suggestion!! I hadn’t thought of having a grey
moonstone faceted. It is exactly the color I am looking for.

Thank-You!
Sincerely,
Terri Sidell


#13
However, it won't really appear gray, in any reasonable size. 

This material will cut a reasonable sized stone and still appear
grey.

The average thickness of the glass is 10mm so a stone with an
overall depth of 10mm can be cut and still show grey.

The glass does not loose colour because it is facetted

As this is not a discussion on faceting but a question on a suitable
material suitable to cut a grey stone, TVite is a good choice.

Cheers, Ivan


#14

Leonid,

There are stones which are typically cut in cabochans due to their
otical phenonemon as you stated. I have purchased some lovely stones
from Shirley at Gem Resourses that are faceted such as Labradorite.
I see she has faceted white Moonstone. Most Opals are also cut into
cabs, except the Mexican Fire Opal.

Sincerely,
Terri Sidell


#15

OK. I’ll be the one to ask…Why do you want a grey faceted stone?


#16
I have a amethyst that was in a fire. That stone was turned grey
from high heat. A person could heat an amethyst, slowly to a very
high heat and see if it will turn grey. Heat, starting at a low
temp and raise the temp every half hour, until the stone gets to
about 1000 degrees, check it and see what the color is and if it
still isn't grey, heat it to a higher temp or a longer heating
time. See if this works for you. 

I suspect It probably won’t work. If your amethyst turned grey in
that fire, it’s likely that the grey color comes from smoke/soot that
is either still stuck to the surface of the stone, or got into
fissures/cracks. Quartz itself should not normally be expected to
turn grey. Amethyst, heated, normally might turn pale green or just
colorless, or perhaps retain a little of it’s purple. Heated higher,
some will turn into citrine (gold/yellow/orange). Grey just isn’t in
the list of expected possible results, at least not in the reference
literature I’ve seen, or in my (limited, when it comes to heat
treating) experience. If you’ve a stone with surface reaching
fractures and fissures, however, you could soak it in oil, and THEN
heat it. You could use clear quartz for this too. The oil would
carbonize on heating, and depending on how much is in the stone, you
might get a decent grey look…

Along similar lines, looking for a grey tone, one might even find
diamonds out there with enough black inclusions as to appear grey,
but not yet a black diamond. Probably pretty cheap if you can find
such. And some diamond crystals are actually a grey color, though
usually these are translucent, not transparent.

Peter


#17

That’s funny. I’ve seen some pretty nice faceted moonstone of
several colors.

I guess I was just imagining that.

LJ


#18
This material will cut a reasonable sized stone and still appear
grey. The average thickness of the glass is 10mm so a stone with an
overall depth of 10mm can be cut and still show grey. The glass
does not loose colour because it is facetted As this is not a
discussion on faceting but a question on a suitable material
suitable to cut a grey stone, TVite is a good choice. 

It is a discussion about producing a gray faceted stone, and the
pattern and size have a great deal to do with the color depth.

I have a 16x12, 10mm deep TVite oval in front of me right now, and
you’d need a very good imagination to call it gray. The color is
almost completely washed out. The best you can do is produce as
large a stone as possible, and choose a design that emphasizes color,
probably at the expense of brilliance.

BTW, I have pieces 15mm thick, and if you use the curved part at the
edge of the face, it can be significantly thicker than that.

One way to retain the gray color is not to polish it. Light diffusion
at the surface soaks up enough light to make it appear gray.

Al Balmer
Sun City, AZ


#19

Hi Leonid, about your coment about moonstones needing to be cabochon
cut to show the effect, Im not sure if this is correct ! I have a
facetted spectrolite which shows the same optical effect, I assume
from the same source? Providing the top facet is on the right plane
the stone should still show the effect shouldnt it?

Best wishes,
Philip Wells in Nelson, New Zealand


#20

To all interested in the subject.

I will try to answer several questions in one shot if I can.

What is adularescence?

It is an optical phenomena, which should only be used in conjunction
with precious moonstone, also knows as adularia. The effect is due to
very specific crystallization pattern. Precious moonstone is far more
expensive than perusal of gem dealers catalogues might suggest. What
is sold under the name of moonstone nowadays is simply a heavily
included orthoclase. That you can cut any way you want.

Why moonstone (adularia) must be cut en cabochon to observe
adularescence ?

Precious moonstone is micro layers of orthoclase interspersed with
micro layers of albite. Both minerals belong to feldspar group. The
only difference between them is that for albite to form, potassium
must be present; but orthoclase require sodium. Both metals commonly
present in hydrothermal solutions, and once solution begins to cool
off, both mineral begin to exsolve. Since exsolution of let us say
orthoclase depletes surrounding from sodium, it creates potassium
rich environment and albite would be formed next. The process repeats
itself over and over again creating micro-layered structure.

When such stone cut en cabochon and base of cabochon is oriented
parallel to the layers, a light ray is subsequently bent by each and
every layer until the angle of incidence becomes so shallow that it
reflects from some layer deep within the stone. When this happens ray
of light becomes trapped in one of these layers and will exit on the
side of gemstone by bouncing back and forth. What we perceive as
adularescence is interaction of ray of light with layer boundary. We
cannot see just single interaction, so to produce cummulitive effect
we cut gemstone en cabochon. It creates multiple entry points with
different angles. We can say that cabochon gathers light from
surroundings.

If precious moonstone is faceted, the only facet to replicate the
effect would be the facet parallel to the layers. There are number of
problems with that idea.

  1. If facet orientation is slightly off, the effect would be weak or
    none at all. (In cabochon this is compensated by spherical shape) To
    get a facet in such precise alignment is a very tall order indeed. I
    would suggest that it is beyond ability of most of cutters.

  2. Even if a cutter somehow manages to orient that single facet
    correctly, the effect would be barely noticeable, if at all. It would
    be so weak that it will be totally obscured by other optical
    phenomena. I can conclude by saying that what is called adularescence
    in faceted orthoclase ( we should not call it moonstone ) is not the
    adularescence, but simply a reflection of light from inclusions and
    other crystal irregularities.

Leonid Surpin
www.studioarete.com