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PostPosted: Fri Mar 21, 2008 6:06 am 
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Troy, do you have acces to a refractometer? Maybe you can chuck your grape garnet on there and see what it says.
Or, if you have a spectroscope: check for the almandine sectrum.
And: pull out your loupe and check for bubbles...

it might not be what you think it is... I'm being foolish stating this after seeing the just the pic but there's reasons to think it's paste (glass) :roll:


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PostPosted: Fri Mar 21, 2008 11:29 am 
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No problem Spauwe, I will check those later today and thank you for trying to help me properly I.D. stones, I am always grateful for the "eye of a expert". I have to run and clean some windows. I know, in the middle of a snow storm ( 9+ inches today) what rich people do with there money :? But that is O.K. as long as I am the one taken it :wink: .

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PostPosted: Fri Mar 21, 2008 12:02 pm 
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Spauwe, not to take the thread off course but would you share with us your concerns on the last stone? Were you referring to what could be flow marks/swirls or possible polish through on the crown, or was it something totally different?

Thanks.


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PostPosted: Fri Mar 21, 2008 12:26 pm 
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Troy:
Quote:
I know, in the middle of a snow storm ( 9+ inches today) what rich people do with there money But that is O.K. as long as I am the one taken it
.
:lol: indeed some people don't really get it, do they? Good on you for taking their money of 'm. Now on to the assumption that people have taken off yours...

Mac: at first glance that alledged crown main facet on the left shows irregularities that I wouldn't expect on garnet. Second: the overall cut... (sorry Troy but that has been cut by a blind fella), one would expect a bit more effort with a natural stone. Third: the girdle, it's not at 90 degrees to the table facet... what's going on there? I've seen stones like this before and they were paste. Forth: the chips/dents at the facet edges, garnet is tough and hard and that kind of wear isn't common for loose stones (it might have come out of a setting though)...
You say you see a swirly texture ? Didn't spot that but it would be a dead giveaway. Troy can tell us about that as soon as he's defrosted...

Back to Troy: I CAN'T be called an expert, I'm 8 months into my gemology study and learning new stuff every day (which is the way it should be, I reckon)

I might be fully wrong...


Last edited by Tim on Fri Mar 21, 2008 2:06 pm, edited 1 time in total.

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PostPosted: Fri Mar 21, 2008 12:32 pm 
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It'll be interesting to see how it turns out. The smaller table and cutting irregularites are what tend to make me give it more credit as being a colored stone cut by a human over manufactured paste.

On the swirl comment, it's very hard to tell in a picture like that as tricks of light and shadow come into play. I was actually just asking if that was what you had interpreted as being a glass indicator. I really couldn't make that call from the photograph.


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PostPosted: Fri Mar 21, 2008 1:42 pm 
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Xtreme1, how did you identify your stone as a garnet?


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PostPosted: Fri Mar 21, 2008 7:00 pm 
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O.K. I am some what warm again.

#1 Spauwe's anwsers; R.I. 1.772, Spectroscope (keep in mind I am very new to this tool) line at 460 to 465? (blue area), big line on 500 to 515? (green area), another big line at 525 to 535? ( green area), another big line at 565 to 575? (yellow /green area), line at 625? (red area). Polariscope looked like a x in the stone (crossed fields) still learning to use these tools.

#2 MacGyver, I failed to clean the stone enough before pics :oops: and I am have a real hard time learning the tricks to shooting colored stones (dark ones), any help would be welcomed :D

#3 Barbra, I received this stone from a friend whom has been a Goldsmith for 25 to 30 years, he came by it from a dealer out of Brazil? I think. He loves weird stuff like me, so he bought 2 :smt033 I need more friends like this :D !

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PostPosted: Fri Mar 21, 2008 7:44 pm 
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Me wrong then... RI + almandine iron spectum are diagnostic. Forget what I said about the cut and cherish the colour ;)

but:
Did you take an RI of one of the pavilion facets as well to rule out a composite? I know, I can be a pain but a good gemologist has to rule out ALL possibilities. Check for lustre diffrences between crown and pavilion as well...


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PostPosted: Fri Mar 21, 2008 7:57 pm 
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Image

Image

Image

Image



I think it's pretty safe to say that unless there is something very unusual out there, these are probably about as good as they get. =D>


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PostPosted: Fri Mar 21, 2008 8:16 pm 
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Interesting collage, Mac.

I think it's a trade-off between color and tone vs. brilliance. The "dark garnet" problem is well known among cutters and there seems to be a tipping point at which certain purple garnet hues become mini "black holes" and return little or no light.

Various special cut designs have been put forward to try to solve the problem, along with suggestions that pavilion facets be cut at or below the critical angle. I haven't found any of the former that really work (but I haven't yet cut them all yet!), and the latter just seems to create purplish stones with big windows.

I don't claim to know it all by any means. But I've tried many cuts over a period of years with almandines and pyrope-almandines from a wide variety of sources and have found the foregoing to be generally true. Some faceting patterns do yield more brilliance than others but I haven't yet found one that provides brilliance across the full face of the crown.

Individual taste also plays a role. Some people just like dark stones and don't care about brilliance/scintillation. Different strokes...

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PostPosted: Fri Mar 21, 2008 8:30 pm 
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That's very interesting Rick. Not being a cutter I wasn't familair with that trait of these stones, but it sure does answer a lot of questions. Personally I'm a big fan of the brilliance/scintillation camp and hate windows.

I'm guessing the rP 6/4 is about as grape as you could hope to get.

Thoughts?


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PostPosted: Fri Mar 21, 2008 9:36 pm 
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Hey Spauwe, I just took the R.I. from the pavilion and it is 1.772 also I could not see any differents between the lustre of the pavilion and the crown.

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PostPosted: Fri Mar 21, 2008 11:32 pm 
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Rick try this cut on your next garnet.

Image

You can download the design here:

http://www.preciousafricangems.com/html/facet_designs.html

It's the second one from the bottom. Uses an 80 index, other than that it's very easy to cut. I find it works really well in garnets.

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PostPosted: Fri Mar 21, 2008 11:48 pm 
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Precision Gem wrote:
Rick try this cut on your next garnet.

... I find it works really well in garnets.


Will do, Gene. I have an 80 index and use it quite often. Your material appears to be much lighter in tone than some of the purples already posted though. I'll try the design with some of my Royal rough. I have some that's darker as well.

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PostPosted: Sat Mar 22, 2008 9:43 am 
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Hi Preciousgems

WOW that is incredible :shock:
all the gemstones you cut are fantastic , just wish i had the money to buy all the wishlist ones i have :wink: well maybe i'll win the lottery and well then i wake up :wink:


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