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PostPosted: Fri Sep 15, 2006 1:43 pm 
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Location: Western NY
SRB - standard round brilliant (variant of RB)
GTL - GIA's Gem Trade Laboratory
G&G - Gems & Gemology (GIA's trade journal)
ct - carat (gemstone weight)
kt - karat (metal purity)

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PostPosted: Fri Sep 15, 2006 1:47 pm 
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DR
ADR
BR
Cabochon: en-cabochon cut stone
J of G: The Journal of Gemmology (Gem -A periodical)
G & J: Gems & jewellery (Gem-A periodical)


Last edited by Doos on Fri Sep 15, 2006 1:50 pm, edited 1 time in total.

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PostPosted: Fri Sep 15, 2006 1:49 pm 
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Location: The frozen north prairie :-/
U-/+ = Uniaxial negative/positive
B-/+ = Biaxial negative/positive
SG = Specific Gravity
AGG = Aggragate

Hmm ... might this get carried away? There are so many, i.e., EC, PS, RB, MQ, etc., it might get out of hand!


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PostPosted: Fri Sep 15, 2006 1:51 pm 
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Great.
Let's keep these coming with attached definitions.
Saves me time.
Thanks.


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PostPosted: Fri Sep 15, 2006 1:55 pm 
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DR - Double refractive
ADR - Anomalous Double Refractive
BR - Birefringent (see DR)
Berekley - Berkeley


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PostPosted: Fri Sep 15, 2006 2:02 pm 
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Location: Sweden
FGA - Fellow of the Gemmological Association of Great Britain
RI - Refractive Index
TIR - Total Inner Reflection
CZ - Cubic Zirconia
YAG - Yttrium Aluminium Garnet
DR - Double Refraction
CIBJO - Confédération International de la Bijouterie, Joaillerie, Orfèvrerie des Diamantes, Perles et Pierres

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PostPosted: Fri Sep 15, 2006 2:09 pm 
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Location: Sweden
GG - Graduate Gemologist. Awarded by the Gemological Institute of America
AG (CIG), Accredited Gemmologist from the Canadian Institute of Gemmology
FCGmA - Fellow of the Canadian Gemmological Association
FGAA - Fellow of the Gemmological Association of Australia
FGG - Fellow of the German Gemmological Association
AA-CJI - Accredited Appraiser of the Canadian Jewellers Institute
AM - Accredited Member of the American Society of Appraisers
ASA - Accredited Senior Appraiser of the American Society of Appraisers
CAPP - Certified Appraiser of Personal Property
CGA - Certified Gemologist Appraiser
CMA - Certified Master Appraiser
CSM - Certified Senior Member of the National Association of Jewelry Appraisers
MGA - Master Gemologist Appraiser
ISA - International Society of Appraisers Accredited Member

Missed out on any? Found a site from which I stole these;
http://reneenewman.com/qa.htm#gem%20diplomas

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PostPosted: Fri Sep 15, 2006 4:17 pm 
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Location: San Francisco Bay Area, CA
HPHT = High Pressure High Temperature treatment for diamonds
Be-heated, Be-treated = Beryllium treated sapphire
AIGS = Asian Institute of Gemological Sciences
AGTA = American Gem Trade Association
HSN = Home Shopping Network
JTV = JewelryTelevision
FTC = Federal Trade Commission
FCC = Federal Communications Commission

Granted, not all of these are "gemological" abbreviations, but they come up on the forum from time to time, so I figured I might as well list them.


Last edited by gem-n00b on Fri Sep 15, 2006 6:46 pm, edited 1 time in total.

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PostPosted: Fri Sep 15, 2006 10:46 pm 
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The list looks done:
http://gemologyonline.com/acronyms.html
Tell me if something was overlooked


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PostPosted: Fri Sep 15, 2006 11:19 pm 
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Location: St Louis - Mo
Doos, I have something like that light box, has the daylight fluorescence bulb and a UV. Its palm sized and cost around 30 dollars. Unfortunately, it doesn’t have the field of view your dream machine has. Mine only has about 2 inches of room between the light source and the white viewing tray.
Cant find mine, but here is one like it for around $60 US, only cooler and uses LEDs. http://www.fdjtool.com/store/showitem.a ... 65&store=5

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PostPosted: Sat Sep 16, 2006 8:26 am 
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Thanks Daniel, I just realized that the colour temperature alone is not sufficient. One needs to know the CRI of the light aswell. preferably as close to 100 as possible.

Barbra,
TIR = Total Internal Reflection
CRI = Color Rendering Index
nD = refractive index with sodium light (589.3nm - Fraunhofer D-line)


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PostPosted: Sat Sep 16, 2006 10:46 am 
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Doos wrote:
Quote:
Do you think the red dot &/or tilt test still apply for a CZ coated with diamond?


Yes of course Peter, well cut RB Diamonds fail the dot test due to TIR, the coating will have some effect on it but it will not create the TIR in the CZ. It just alters the path of the incident light a bit and probably increase the surface reflection on the Diamond/CZ layer at the table.
We could easily calculate the effect with the laws of refraction and reflection.


Uhum, I did the calculations and I was wrong. The tilt and spot tests will probably fail.
Here is the image I drew with the calculations:

Image

The lightray (red line) reaches the table of the coated material at 90°, so no refraction will occur .. so it will go straight through to the pavillion of the CZ. It reaches the pavillion at 50°.
You would expect that the lightray would now be reflected back inside the CZ because it falls outside the critical angle of CZ (approx. 27°), but TIR only works when light travels from an optically denser to an optically rarer medium. In this case the CZ is the rarer medium .. so the lightray will refract inside the Diamond coating. (btw the ca of 27° is between CZ and air, the ca of CZ/Diamond is about 64°).

It will refract at an angle of 35° degrees into the coating (usual Snell's Law calculations .. n1 sini = n2 sinr) and reach the pavillion at 55°. As this 35° is larger than the ca of Diamond/air (approx. 24°), the light ray will be totally internally reflected. So the ray reaches the CZ/diamond boundary again and will be refracted inside the CZ (no TIR here because the ca is larger than the angle of incidence) .. then the process repeats a few times untill the the ray reaches the table of the coating .. there it will refract outside the stone.

So, unless I am wrong now .. I was wrong before. Anyone care to double check this with different angles?

p.s.: Barbra, ca = critical angle

(edited for better image)


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PostPosted: Mon Sep 18, 2006 7:52 am 
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Quote:
So the ray reaches the CZ/diamond boundary again and will be refracted inside the CZ (no TIR here because the ca is larger than the angle of incidence) .. then the process repeats a few times untill the the ray reaches the table of the coating .. there it will refract outside the stone.


So, if I'm understanding you correctly, a CZ with a diamond coating will actually look like a diamond. They're not just pitching some marketing gimick at us. Wow, that's pretty cool.

Has anyone seen any gem lab studies on this stuff?

(Doos -- thanks again for doing the diagram thing. It really helps some of us catch up!)

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PostPosted: Mon Sep 18, 2006 10:54 am 
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Doos wrote:
Quote:
TIR = Total Internal Reflection
CRI = Color Rendering Index
nD = refractive index with sodium light (589.3nm - Fraunhofer D-line)


Done!


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PostPosted: Mon Sep 18, 2006 12:09 pm 
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Quote:
So, if I'm understanding you correctly, a CZ with a diamond coating will actually look like a diamond.


The look will be different I'm sure, but the dot/tilt tests will probably fail.


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