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Fragile gemstones


#1

All, Noel asked about a list of faceted stones that have been
observed to be more prone to chipping than in the past. This is my
own list, from my own cutting experiences. Top of the list is
tourmaline. I think that tourmaline are being subject to very high
heat trying to lighten the color and make the stone less murky. Next
on my list is quartz. I think quartz is being subjected to both heat
and radiation treatment. By this I mean amethyst, citrines, and Oro
Verde. Third would be zircon. I have heard of experiments being
conducted with radiation and heating to make golden zircon blue.
Forth would be topaz. Both the golden topaz and blue topaz. Fifth
would be the beryl’s, both golden and blue. I have not heard or
encountered any problems with morganite.

Some of these stones are so prone to chipping that I have gone to
8,000 diamond on polishing laps to fine grind. A 1200 diamond lap
would leave facet edges so brittle that they would break out during
polish with 50,000 diamond.

What this means to jewelers is that if you run a polishing buff over
the stone you will probably dull the stone and abrade the facet
edges. Any impact on the stone may yield a damaged stone.

Gerry Galarneau
@Gerry
www.galarneausgems.com


#2

Hi I bought twenty carats of Sandawana emerald from the mine
opererators in 1mm-4mm round stones.These stones are so fragile that
I have had several pieces of jewellery come back with shattered
stones. So much so that I don’t use them any more. Earlier parcels
that I bought from them were not nearly so fragile.I have heard of
several reports of super fragile emerald from some gem cutting
buddies around South Africa. Also some of the setters
are moaning big time… Cheers, Hans Meevis


#3

I have also noticed an acute fragility with watermelon tourmaline of
late. The question here is…are treatments also being used on this
tourmaline or is it just my aging fat fumbling fingers? One comment
was made to me by an associate that watermelon tourmaline is never
treated as it is already of light color. Nonetheless, someone out
there in the ‘treating’ community may have found some reason to do
something with it such as sharpening the color bands etc?!

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut1


#4

Hi Don ! Multi-color tourmalines have ALWAYS been very fragile. The
color separation line is usually the critical area. I have always
steered clear of un-cut bi or tri colored tourmalines for just this
reason. Lately I have noticed that these stones have been more
readily available on the market as cut stones. When the stones have
survived the cutting process you can have better assurance of their
survival . Nonetheless, I would certainly never mount them in such a
way as to expose them to impact.Ron at Mills Gem, Los Osos, Ca.


#5
 Nonetheless, someone out there in the 'treating' community may
have found some reason to do something with it such as sharpening
the color bands etc?! 

They do heat the bi colored stones, but not to sharpen the band.
The sharper the color band is, the more likely it is to
fracture/seperrate at the band. I have some rough peach tourmaline
that has a green cap on it. On some of the stones, you can pop the
cap off with your fingernail. The green is a secondary growth and
is not truly a part of the original crystal.

Don


#6
I have also noticed an acute fragility with watermelon tourmaline
of late. The question here is....are treatments also being used on
this tourmaline or is it just my aging fat fumbling fingers? One
comment was made to me by an associate that watermelon tourmaline
is never treated as it is already of light color.

Hi Don, After benefitting from so many of your postings, over the
last year or so, it feels great to be able to return the favor…

The truth of the matter is that most “true” Watermelon Tourmalines
– i.e. pinks, with green rinds (as opposed to Bicolor Tourm’s,
which display two or more colors in striae, perpendicular to the
crystal axis) – are not treated, except through gentle heating,
which tends to reduce the brown overtones inherent in some of them.
The more garrishly colored pieces you’ll occasionally see, nowadays,
with their intense blue rinds and violet-red Rubellite cores are,
indeed, often the result of a bit of irradiation, but this shouldn’t
detract from their overall durability, unless they’ve been
overheated, in the process.

The single biggest source for confusion and frustration with these
gems, as a whole, seems to stem from jewelers’ lack of understanding
of some of the chemistry/mineralogy involved in the whole pink range
of Tourmalines, in general, and those with multiple colors, in
particular. The real culprit behind these, lurking unbeknownst to
most, is the element lithium, which imparts its pink color to not
only these beauties, but several others in the gem & mineral
kingdoms. Lithium is both a blessing and a curse, like its sister,
chromium. In both cases, these elements’ presence in a given
crystal’s molecular lattices, in relatively small percentages,
causes both beautiful coloring and crystallographic instability; as
with the chromium in fine Emeralds or Rubies, the more lithium you
add, the better the color AND the more included and tempermental the
finished gem.

From a lapidary’s perspective, faceting multicolored Tourmalines
requires taking steps usually reserved for far less hardy materials,
like Apatite or Rhodochrosite. In order to guard against a bicolored
rough’s tendency to split along its color lines, the lapidary must
"rough out" the stone with a much finer lap than he’d otherwise use,
and must also take precautions to use only warm water as a coolant,
lest any thermal shock occur and split or shatter the stone.
Similarly, when polishing, care must be taken to assure that the
polishing lap remains smooth and true, without irregularities that
could, again, split the stone.

Alas, when a great many setters receive these stones – regardless
of whether the pieces in question are true, rinded “Watermelons” or
bicolors – they see them as just another splotch of color, and
treat them without any regard to their inherently delicate nature.
As a result, I’m often asked to repair the unrepairables: stones
that’ve neatly split into a green half and a pink half, or a few
green “rind” chips and a pink core. (Yes, there are some
cyanoacrylates that are suitable for such repairs, but do you want
to be the one to tell your customer how her stone came to feature
that glue line? I sure don’t!) In summary, the best advice I can
offer you, Don, is to handle every mutlicolored stone you see as if
it were a 1.0mm thick Opal cabochon (very delicately), and/or expect
problems to arise otherwise, each time the beautiful pink thing in
from of you isn’t a Sapphire, Spinel or Rhodolite.

Hope I’ve helped,
Doug
Douglas Turet, GJ
Lapidary Artist, Designer & Goldsmith
Turet Design
P.O. Box 162
Arlington, MA 02476
Tel. (617) 325-5328
eFax (928) 222-0815
anotherbrightidea@hotmail.com


#7
bought twenty carats of Sandawana emerald from the mine opererators
in 1mm-4mm round stones.These stones are so fragile... 

Hans, I have just had the wonderful experience of channel setting
that garbage and it is not cheap. Minor pressure from your thumb nail
can shear it. I cannot wait for the customer to try and wear it.

Regards J Morley Coyote Ridge Studio


#8

All, On the subject of tourmalines. I have recut about 500
tourmalines in the last two years. Most of these stones were cut in
Asia or Brazil and I recut them. Cutting from already fashioned
stones has been the most problematic. I have noticed that most of the
pink tourmaline is very fragile. Just today out of four stones I
worked on the pink tourmaline gave me many problems obtaining a
satisfactory polish. None of the other tourmalines were problematic.
I attribute these problems directly to heat treating. Multicolored
tourmalines have always presented problems. A Himalayan stone from
California that weighed 15+ carats when finished, of nice red one
side and bright green on the other still is a nightmare. A friend
of mine had finished the stone and placed it in a stone paper. I was
going to a show and he asked me to take the stone to display it and
possibly sell it. When he opened the paper there laid two stones. It
had split directly on the color line with no chips or fragments.
This was a very costly stone. I have encountered no problems with
multicolored tourmalines from Africa. Most of our newer stock is from
Namibia and except for the bright greens we have had no problems. I
suspect that the bright greens are being subjected to high heat, just
like the pinks and the treatment is creating polishing problems.

Gerry Galarneau
@Gerry
www.galarneausgems.com


#9
One comment was made to me by an associate that watermelon
tourmaline is never treated as it is already of light color. 

Hi Don, I don’t have an authoritative response, but an anecdotal one.
I bought a nice watermelon tourmaline crystal in matrix specimen at a
rock shop in Florida several years ago. I discovered last year that
the colors have lost a great deal of the intensity they had when I
acquired it. The specimen has had limited exposure to direct light,
so I surmise it was treated in some way, and that treatment is not as
permanent as I would have liked.

Another piece in the puzzle?

Dave
Dave Sebaste
Sebaste Studio and
Carolina Artisans’ Gallery
Charlotte, NC (USA)
dave@sebaste.com


#10
I discovered last year that the colors have lost a great deal of
the intensity they had when I acquired it. The specimen has had
limited exposure to direct light, so I surmise it was treated in
some way, and that treatment is not as permanent as I would have
liked. 

Hi Dave

There are a couple thing at play here. I run into jewelers who want
to look at stones “under their own light”. You and I both know that
the reason for this is that you know what your lighting highlights
and you don’t know what a show dealer, or another shops lights
highlight. This is probably not what you experienced though.

As I am writing this post, I am looking at a 32ct Russian Bi colored
Topaz that I bought three years ago in Tucson. I bought the rough,
a nice pale blue/brown bi colored piece. I asked about color
stability and was told “no problem”. The stone I am now looking at
after cutting two years ago is a white topaz with just a shade of
brown in one corner if you look closely. Not the sharp color split
and interplay I saw when the stone was first cut. It has only seen
a few hours on display, the rest of it’s life was in a safe. I was
assured that my rough had not been treated. Oh well

When I had my store active, I would keep opal under lights for at
least a year before offering them for sale. It never occurred to me
that I should do the same with tourmaline or topaz. I knew that
Amethyst wouldn’t stand the light, some times, and I knew that some
of the brown topaz would fade with light. Boy are there a lot of
pitfalls for the jewelers. Treatments, synthetics, and fillings to
name a few. Lack of knowledge on their part can cost them.

I was in a local jewelry store today, and in chatting with the
owner, I told him that I had been cutting a lot of Demantoid in the
last few months. His response was “Demantoid, I don’t think I have
heard of it”. This guy has been in business for over 20 year at the
same location. He wouldn’t know the difference between a
refractometer and a polariscope, never mind what they had to do with
the business. No wonder that the scam artist flourish. There is a
steady stream of marks for them.

It sure makes it a problem for people like you and me who want to be
honest with our customers, and who tend to believe that our
suppliers are honest with us. That one supplier gets through our
defences and sticks us with a dud, and who eats it, US. We would
not knowingly pass it along to our customers. When we find out that
it is not what we thought, we eat the cost. Our customers never
take this into consideration when working with us. They don’t know
and we don’t tell them. Where we might run into trouble is selling
one of these duds to a customer, not knowing it.

A painful story before I log off. My son got married about four
years ago. I sold him the engagement set. I set the main stone.
After he got the set, he took it to his best man’s father for an
appraisal as I told him to. The guy told him some story about
setting damage and being a used stone but not to worry as many of
the diamond were “used”. Then, just before the wedding, I had to
replace the engagement band as the matching wedding band was no
longer available. I had a friend reset the main stone into the new
band. My Daughter-in-law proceeded a year later to smash the ring
in a filing cabinet, and they took it to a local jeweler to have the
head replaced. This jeweler “mapped the stone” so my son could see
that he was getting the same stone back. At Christmas last year,
they were at my house. As always, I offer a cleaning and inspection
on jewelry. When I looked at the main stone, I was aghast. It was
not the stone I sold my son. It was damaged, the girdle had been
ground on something. It was awful. I pointed it out to my son and
his comment was that the jeweler who had replaced the head had
pointed these thing out to him and it was the same stone. Now talk
about being between a rock and a hard place. One of a number of
things could have happened. My son’s best man’s father could have
swapped stones. My friend who reset the stone could have swapped
stones. The local jeweler could have swapped stones. But the bottom
line is that this is a very uncomfortable topic of discussion
between me and my son now. I know that the stone in my daughter in
laws ring is not the one I sold them. My son is sure it is but is
happy with it. I would like to catch the crook.

Don


#11

Hi Don, I really felt for you when I read your post about your
daughter in laws engagement ring. My post could really go under the
heading of favorite warnings.

One safety precaution is to take a good digital pictures of any
expensive stone, and not just one but several positions. Keep them
on a disk, and that way the proof is there. It is something to try.

Diane Sadel
http://www.sweetgemstones.com