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Moissanite


#1

Hi Chrissy,

It is Professor Henri Moissanite that first discovered
moissanite in 1904. Moissanite is the natural hexagonal polymorph
of SiC. It occurs in meteorites, a little gift from above, and
also had just been found in kimberlite rocks from Yakutia in
Russia, but they occur only in small grains ( around 1mm ). The
grains can be green, blue, black, transparent and yellow. It has
a hardness of 9.50, specific gravity of 3.218 and a refractive
index of 2.654 - 2.697. The fracture is conchoidal, cleavage not
determined.

There are also an unnamed natural cubic form of SiC and a
natural trigonal form of SiC.

The synthetic form of SiC is called Carborundum and have all the
same properties.

In 1907 the first application of silicon carbide was produced as
an abrasive and cutting material. Today SiC has been called the
"material for the future" due to its many applications.

For people in the jewellery trade SiC or synthetic moissanite is
a very exceptional good imitator of diamond. Because of its
properties such as high thermal conductivity, hardness 9.50,
diamond hardness 10, refrative index 2.65, diamond RI 2.42,
specific gravity 3.21, diamond SG 3.5, this material is the
closest to diamond than any other gem materials. Most jewelers
who had the opportunities to look at the material mistakenly
identified synthetic moissanite as diamond!!!

C3 Inc. plans to begin distributing its artificial gemstone in
the first half of 1998, in the US and the Pacific Rim. Also C3
Inc. is taking a very strong position about the full disclosure
of the qualities of synthetic moissanite.

Apparently synthetic moissanite will cost more than CZ but much
less than the natural diamond : $50 to $ 70 per carat??? The
annual market for CZ at present is over $ 200.millions.

Three characteristics of synthetic moissanite:

  • it is doubly refractive,
  • it has white ribbon-like inclusions,
  • doesn’t show an absorption spectrum line at 415nm as 95 % of
    the natural diamonds do.

Best regards,

Francoise.


#2

Hi Francoise: Thanks so much, I am impressed, where did you find
out all that info? thanks I understood everything except about
the absortion line of 95% does that mean it will be an
irridescence to it or could you explain, I am a diamond grader
but was never that great on the technical end . but I think this
one is very important to watch, is it going to be 50-100ct. or
$300.00 ct. . Thanks for all the help!

Sincerely
Chris
http://www.tace.com/glitters


#3
    I understood everything except about the absortion line of
95% does that mean it will be an irridescence to it or could
you explain

Hello Chris,

Diamonds are broadly classified into different types, this is
done on the basis of the differences in their respective
absorption in the ultraviolet section of the spectrum.

Type Ia diamond : Most Natural Diamonds Are Of This Type (about
98%).They do contain nitrogen in about up to 0.3 % that have
been distributed in form of sub-microscopic platelets or
precipitate within the crystal. Diamonds of this type will
normally have a body colour ranging from near-colourless to
yellow and will be classified in a subcategory as type IaA, the
strongest absorption lines for Type IaA diamonds is located in
the violet part of the spectrum at 415.5nm. Further lines can be
seen in the violet and the blue part of the spectrum at 478.nm.,
465.nm., 452.nm., 465.nm. and 475.nm. Diamonds of Type Ia with a
body brownish grayish body colour will be subcaterised as Type
IaB and show a strong line in the absortion spectrum at 504.nm.
in the green and may be two weaker lines at 537.nm and 498.nm.,
they may also show the line at 415.5nm. Diamonds Type Ia are
often referred to as the “Cape” series.

Type Ib diamond : occurs very rarely in nature and account for
about less than 1 %. Their nitrogen content is lower at 500ppm.
and in dispersed form. Diamonds Type Ib have a very deep yellow
body colour. All synthetic diamonds containing nitrogen are of
Type Ib. All natural and synthetic Type Ib diamonds do NOT have
any sharp bands in their absorption spectrum.

Type IIa diamond : also they do occur very rarely in nature and
contain so very little nitrogen that it cannot be detected with
normal infrared methods. Those diamonds do possess a very
significant higher thermal conductivity than Type I. Normally
those diamonds are colourless. Most large diamonds are Type II.
Type IIa diamonds do NOT have any sharp bands in their absorption
spectrum. Most of Type II diamonds are Type IIa.

Type IIb diamond : those diamonds are the rarest of all, less
than 1/1000 Type II diamonds will be of Type IIb. Those diamonds
are free of nitrogen but instead they contain traces of boron and
aluminum. Type IIb diamonds are semi-conductors of electricity,
in contrast with the other types. Type IIb diamonds will include
all of the natural blue body colour diamonds, they can also be
grey and sometimes near-colourless. Type IIb diamonds do NOT show
any sharp bands in their absorption spectrum. The very famous
"Hope" blue diamond belongs to this category.

Type III diamond : they have been discovered in meteorites.
Instead of a cubic crystal structure they have an hexagonal one.
They go by the name of “lonsdaleite” as they were discovered by
Dame Kathleen Lonsdale.

Spectroscopy is a very useful tool for diamonds. If you do find
one or more sharp lines at 415.nm, 423.nm, 435.nm, 452.nm,
465.nm,478.nm, 504.nm, 592.nm you can immediately identified this
diamond as a natural. The vast majority of natural diamonds 98 %
will fall under these categories and are of Type Ia.

HOWEVER IF YOU DO NOT FIND ANY BAND IN THE SPECTRUM IT DOES NOT
PROVE THAT THIS STONE IS NOT A NATURAL DIAMOND OR A SYNTHETIC OR
A SIMULANT. YOU CANNOT MAKE A POSITIVE IDENTIFICATION ON THIS
BASIS. Further testing will be necessary.

Sharp bands may not always show in the spectrum and are not
always immediately seen in each stone. In many occasions you do
have to cool those stones before you can detect their spectrum.

The spectroscope as well as the “Diamondsure” will differentiate
naturals diamonds from synthetic diamonds by about 95 %. The
stones that fail those tests need further investigation.

Chris, do you have a polariscope ? It will differentiate all
your stones from singly refractive to doubly refractive, very
useful for parcel containing stones of same colour or colourless
and more.

Moissanite is doubly refractive, diamond is singly refractive.

Best regards,

Francoise.


#4

Hi Francoise: Thanks for the explanation, no I only have a
refractometer, a GIA Scope and a diamond tester and carbon tip
pen, and really hardly use any of the instruments, usually I
depend on my loupe unless it looks to good to be true. Sincerely
Chris http://www.tace.com/glitters


#5

Pictures of typical diamond spectra as well as synthetic diamond
spectra can be found on my website at http://www.gis.net/~adamas/
Franscoise’s explanation is a complete as you can get without
the transmittance pictures. ; Also the SAS2000
Spectrophotometer Analysis System clearly deliniates possible
synthetic diamonds as opposed to the on/off “detection” of the
DeBeer’s DiamondSure…

Although I do not have a spectrum of moissonite available, last
year in Tuscon I took one and as I remember it appeared as like a
high pass filter with a rather sharp cutoff in the 450-470nm
range if my memory serves me correctly…

Marty Haske


#6
Spectroscopy is a very useful tool for diamonds. If you do find
one or more sharp lines at 415.nm, 423.nm, 435.nm, 452.nm,
465.nm,478.nm, 504.nm, 592.nm you can immediately identified this
diamond as a natural. The vast majority of natural diamonds 98 %
will fall under these categories and are of Type Ia.

Francoise,

Hello, this was an excellent breakdown of the diamond types,
however perhaps it would be wise to just add a small piece here.
These sharp lines do help identify the diamond as being of
natural origin, but I hope you agree that they do not
necessarily mean that the stone is of natural COLOUR origin.
These absorption lines may be found in natural stones, but they
may also be found in treated natural diamonds !!! Fair comment ?

best wishes to everyone for Xmas and I hope you all have a
wonderful, happy, prosperous and healthy 1998.

Nick


#7

Hello Nick,

You are absolutely right. Thank you for your valuable input.

Best regards,

Francoise.


#8

All: I’m no great expert, but I know this: if you deal in diamonds in
any way, shape or form, you’d better learn about the property of
double-refraction or buy a tester. I believe Moissanite is going to
be a nightmare, especially in the secondary market when stones are
traded in or upgraded, when jewelry is sold by non-jewelers to other
non-jewelers, or when jewelers are buying off the street or taking
jewelry in for repair.

Learning to distinguish between single and double refraction is
simple and should become a routine, on-the-spot part of diamond
transactions of any kind. Every stone should be tested every time it
comes in to your shop, even though that sweet little lady who’s been a
customer of yours for years bought the ring from you just an hour ago.
Even sweet little ladies have been known to switch stones.

Diamond is singly refractive. Moissanite is doubly refractive. If
you’re experienced you can tell the difference with a 10x loupe by
looking for doubling or fuzzing of the back facets. But I know for a
fact that Mossanite is being deliberately cut with the table
perpindicular to a direction of single refraction (DR stones have at
least one direction of SR) which makes that test just a little bit
trickier. You have to view the stone from several directions, not
just downward through the table, to be certain. The effect is much
easier to see in a microscope of around 30x. Best yet is a
polariscope. You can make one yourself if you’re handy or buy one for
around $210 (Kassoy) or more from the GIA.

But I’d think anyone who can afford to deal in diamonds should be
able to manage the $300-$400 necessary to buy both a thermal
conductivity tester for CZs and some other diamond simulants, and a
Moissanite tester. They’re being offered by many suppliers, and
considering the potential financial loss from one bad deal, I think
they’re a bargain. I’m not a shill for Kassoy but I just received
their new catalog a few days ago and they have several "matched pairs"
of testers for under $400. (Kassoy: 1-800-4-KASSOY).

Once you’ve jumped the CZ-Moissanite hurdle you can then devote all
your attention to finding out if the diamond has been laser-drilled to
eliminate inclusions, glass filled to hide cracks, color-enhanced or
is a Russian-made stone (they come in colors, too!)

Rick Martin


#9

I have a customer who needs two 10.5 mm round moissanites. I won’t
sell synthetics but I figured I would offer this sale out to anyone
on Orchid who might. If you contact me off list I can put the two
of you in touch.

Daniel R. Spirer, GG
Spirer Somes Jewelers
1794 Massachusetts Ave
Cambridge, MA 02140
617-491-6000
@spirersomes
www.spirersomes.com


#10

How about Moissanite? The moissanite I’ve seen - admittedly not
much, because at this point even moissanite is priced 'way beyond my
means - has MUCH more sparkle and attraction than any diamond I’ve
ever seen. And yes, I’ve seen the Very Expensive supposedly High
Quality diamonds in places like Tiffany’s in New York, and in various
Expensivo shops and boutiques along the Magnificent Mile in Chicago.
I wasn’t always poverty-stricken.

I’ve also been wondering about how fragile (or not) moissanite is.
I’ve been told by Real Jewelers that setting diamonds can be tricky,
that they’ve had them split or chip (I may not be using the correct
terminology) if you apply just a bit too much pressure when setting.
It seems they’re not as indestructable as one might think… I’ve
been told that emeralds and rubies can be difficult to set without
damaging them, too. I have little experience setting stones, and
certainly none with expensive stones.

    When I say that I'm "not partial to them" I mean that I'm not
inclined to favor them over another. I don't hate or even dislike
them, only the greasy marketing hype that has been supported by a
lot of the industry. 

I don’t care for diamonds (as I’ve repeatedly said, VBG) but if I
seem actually averse to them, I’d have to say its the sense I have
from the pimping ad campaigns that we’re only worth the rocks our
johns buy for us.

That ad with the woman who can’t be bothered to say anything nice to
her SGO until he reaches into his pocket and hands her the rock
keeps flashing back to my mind every single time I see a diamond -
and its not a pleasant connotation.

As for colored diamonds, the few I’ve ever seen I like better than
the colorless, but again they’re so expensive that I prefer other
colored stones. I’ve not had the chance to do a lot of side-by-side
comparison, but I can’t tell a significant difference between a blue
diamond and any other good quality blue cut stone of approximately
the same hue.

And you know, under strong lights, there may appear to be some
difference - but that’s not the kind of lighting you’re going to be
in when you actually wear the thing in public. Its typical usage
conditions that count.

Somebody else said:

    And that is what we are selling as jewelers--the meaning behind
the ring, not just the ring itself. 

See, that’s the thing. I don’t connect to the whole “meaning of a
diamond” thing. The whole thing was created and promoted, reaching
the hype-height sometime in the 50’s and 60’s. It has nothing to do
with tradition, it’s marketing hype that was created mostly in my
lifetime, and sleazy marketing hype at that.

So if someone happens to find some meaning in a piece of jewelart
that I make and sell (boy, am I getting ahead of myself, I’m still
trying to relearn soldering, but anyway…) well and good. But its
a good bet that the “meaning behind the (whatever)” that they
experience is unlikely to be the same as what I or someone else may
feel or see in that particular piece.

And that’s ok. Everybody’s got their own worldview, and whenever
there’s an intersection, even for just a split second of the small
amount of time we have on this earth, well, that’s a wonderful thing
in and of itself.

It would be ludicrous to require conformity on top of the miracle of
connection that every such juxtaposition represents…

    .... If I ever feel that I have to trade a diamond for what
should be unconditional, I'll get a puppy and live in a cave,
somewhere. But I'll need an alcohol lamp and blowpipe. 

C’mon, James, you’ll need an internet connection, too - we’d miss
you!

Sojourner


#11
As for colored diamonds, the few I've ever seen I like better than
the colorless, but again they're so expensive that I prefer other
colored stones.  I've not had the chance to do a lot of
side-by-side comparison, but I can't tell a significant difference
between a blue diamond and any other good quality blue cut stone of
approximately the same hue. 

To my eyes, the difference is readily apparent. First off the fire
and refractive qualities of a diamond aren’t lost when the stone is
blue, pink, whatever. So you have the liquid blue of a topaz
combined with the “life” of a diamond.

Additionally, in two or three years, that diamond is going to look
every bit as good as it did on day one-- providing it hasn’t been
thoroughly abused (they are hard, but hardly indestructable)-- and is
kept clean (the smutz that eventually coats the back of all stones
will dull a diamond as well as any other stone: the cleaner the
stone, the brighter the bling). Most colored stones, including
corundum (sapphire/ruby) to a lesser degree, will have rounded facet
junctions, scratches and various abrasions in the course of that
time. They often end up looking mushy. With a diamond, small melee
for instance, that sharp and bright pinpoint of precision will be
there for the life of the piece.

When I’m making work, I use whatever material will get my point or
intent across. This may be diamond, may be lead, bronze, bone,
acrylic, paper, tile grout, yadda, yadda. As long as the materials
fill my own set of PERSONAL requirements regarding form, function,
content, durability, social responsibility, at times even
marketability, etc. I’ll use it. It’s all fodder, and it’s all my
personal choice. Incorporating diamond into an object built from
base metal or even a prosaic organic material such as beef bone is
hardly new thinking: it’s been done for many, many years.

Respectfully,

Andy Cooperman
coopermanjewelry.com or andycooperman.com


#12
I've been told by Real Jewelers that setting diamonds can be
tricky, that they've had them split or chip (I may not be using the
correct terminology) if you apply just a bit too much pressure when
setting. It seems they're not as indestructable as one might
think... 

No, and that’s one of the ironies of the whole “A Diamond is
Forever” campaign. Diamonds may be the hardest substance, but
they’re not the toughest. Start throwing diamonds and pieces of
jade against a wall and the diamonds will most likely chip or break
first. But even little fragments of broken diamonds will be able to
scratch the jade, which is tougher, but not harder.

Beth


#13

to all my peeps…lol,

just wanted to share my moissanite story…fabricated a eng ring
just this last week ( for my little brother no less) using
moissanite…6mm round in the center 4 prong gypsy setting with a
total of 32- 1.75mm round plate set along the sides right up the
prongs with a chatham emerald set in the top of each prong…the
moissanite was no problem to set…looks awesome…the only thing
that put a scare into me (and the info i found did warn me about)
was that i needed to solder somewhat close to the side stones and
they turn bright yellow when heated…when they cooled down they
were fine again…my feeling on using these products is that if the
person wearing them wants to share the info with others that’s
fine…but if not, then let people think what they want…i’ve
always said that if the person wearing the item can pull it off
with class, then more power to them…also just want to say thanks
for the great sense of community i feel from you all

lisa
25 yrs on the bench and counting
lmfsyrny@aol.com


#14
    How about Moissanite?  The moissanite I've seen - admittedly
not much, because at this point even moissanite is priced 'way
beyond my means - has MUCH more sparkle and attraction than any
diamond I've ever seen. 

That’s because synthetic moissanite (natural moissanite is extremely
rare and very tiny) is twice as dispersive as diamond (twice the
fire). Colorless stones are not common, most are greenish,
yellowish, or a combination of the two. Diamond is singly
refractive, but moissanite is doubly refractive with a birefringence
(the difference between its’ refractive indices) wide enough to
where you can see double images of its’ facets when you look through
it with magnification. That adds to its’ fire and sparkle.

    I've also been wondering about how fragile (or not) moissanite
is. I've been told by Real Jewelers that setting diamonds can be
tricky, that they've had them split or chip (I may not be using the
correct terminology) if you apply just a bit too much pressure when
setting. It seems they're not as indestructable as one might
think...  I've been told that emeralds and rubies can be difficult
to set without damaging them, too. 

Moissanite comes in to the mohs hardness scale at around 9.25.
Suitable for jewelry, but diamond is still something like 80+ times
harder than that. By splitting, the Real Jeweler meant cleaving.
Diamond has that cleavage plane that can break fairly easily with
enough pressure during setting, especially with certain fancy
shapes. There are also feathers (what non-Real Jewelers call
"cracks") That can compromise the durability of any gemstone,
including diamond, emerald, ruby, etc. Moissanite has no cleavage
plane, so it’s actually tougher than diamond in that aspect. Any
gemstone can chip or fracture. It’s crystal habit and structure
usually determines what shape that chip (or fracture) will look like
(conchoidal, step-like, splintery, etc.).

Hardness vs. toughness in gemstones has been addressed here many
times. The simplest description is the making of a jade hammer with
diamond abrasives. Once fashioned, the jade hammer can smash a
diamond into bits. Diamond is hard, jade is tough. Neither is
indestructable.

I wouldn’t try the hammer thing with moissanite, though.

James in SoFl