January 24 Through February 4—TUCSON, ARIZONA: Annual show
Welcome to the GemologyOnline.com Forum
A non-profit Forum for the exchange of gemological ideas
It is currently Thu Mar 28, 2024 7:25 pm

All times are UTC - 4 hours




Post new topic Reply to topic  [ 33 posts ]  Go to page 1, 2, 3  Next
Author Message
 Post subject: Gemologist Lab owners what Tests do u use on Colored Stones
PostPosted: Wed Nov 23, 2016 1:39 am 
Offline
New to the Forum or The Quiet Type

Joined: Tue Nov 08, 2016 11:38 pm
Posts: 7
Gemologist and Gem Lab Gemologists
I am specifically asking the opinion of paid professional
Gem lab Gemologists and or owners
and or Active Certified Gemologist Appraisers

Which Tests do you Perform on unknown Colored Stones

For example; You have an Unknown Colored Stone / Gem

Would you please tell us what specific tests you normally perform
if you have an;

( 1 ) Unknown loose colored stone

( 2 ) A Ring with a colored stone that cannot be put on a Refractometer
( because of the prongs )


Please also tell us [b]the order of the tests[/b] that you perform
and if there is a reason for the order.

Would you please List the Details also.
For example if you use a Polariscope in your tests do you
Just look to determine if its double refractive, singly refractive or ADR.
And / or do you also look for the optic sign, uniaxial, biaxial, etc.

Also would you please list the

Names of any Reference Books that you consistently use to identify unknowns
and the exact Names of the equipment that you use.
For example you could say; I use a hand-held diffraction grating OPL Spectroscope, etc

Last, but not least
What problems / issues would cause you to say
"I do not know" "im not sure"
"I would like to send it into one of the large labs", GIA, etc.


Top
 Profile  
Reply with quote  
 Post subject: Re: Gemologist Lab owners what Tests do u use on Colored Sto
PostPosted: Wed Nov 23, 2016 7:24 am 
Offline
Gold Member

Joined: Wed Jan 23, 2013 5:29 pm
Posts: 1047
Location: Paris
I don't really see the point... :roll:


Top
 Profile  
Reply with quote  
 Post subject: Re: Gemologist Lab owners what Tests do u use on Colored Sto
PostPosted: Sat Nov 26, 2016 5:55 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 21602
Location: San Francisco
Calldoug....a simple search on this platform will answer those questions for you.
Everyone has their own approach to gem ID. A lot depends on where you studied.
Where did you study calldoug?
To answer your question "To what extent do you use an instrument, like a polariscope?" As far as you can.

My lab looks like this
Image
I start by weighing and measuring the unknown, describing cut and color.

polariscope
refractometer: many of the German refractometers have a raised hemicylindar to aid with mounted stones.
microscope, making note of diagnostic features
UV cabinet
Specific gravity
and scan with the GemmoRaman

I have several other tools but do not routinely use them, not to mention a gemological reference library with close to 1000 books.

If my results are inconclusive and I am not confident in identity, treatment and natural vs synthetic I advise sending the stone to GIA or AGL.


Top
 Profile  
Reply with quote  
 Post subject: Re: Gemologist Lab owners what Tests do u use on Colored Sto
PostPosted: Tue Dec 06, 2016 3:12 pm 
Offline
Site Admin
User avatar

Joined: Fri May 12, 2006 11:24 am
Posts: 7523
Location: Rome, Italy
As Barbra Said, everyone has his personal approach and protocol to face the issue.
I start always with the microscope then i move the stone on the Raman.
there are VEERY few occasions which may require for further analysis to get a proper ID.

_________________
GemmoRaman-532 - GemmoFTIR - GemmoSphere - EXA


Top
 Profile  
Reply with quote  
 Post subject: Re: Gemologist Lab owners what Tests do u use on Colored Sto
PostPosted: Tue Dec 06, 2016 11:40 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 21602
Location: San Francisco
The Gemmoraman just slam dunks, I mean "confirm", your other test results. :wink:


Top
 Profile  
Reply with quote  
 Post subject: Re: Gemologist Lab owners what Tests do u use on Colored Sto
PostPosted: Thu Dec 08, 2016 1:54 pm 
Offline
Site Admin
User avatar

Joined: Fri Apr 17, 2009 3:53 pm
Posts: 2049
Location: Sweden
I have exactly same approach and method as Alberto but might add a visual inspection by eye first.
If I did not have Raman I would still use the same order and depending on gem color go for spectroscope, dichroscope, polariscope and refractometer. Rarely specific gravity measurement. Most important tool is though in most peoples head, called the brain. An amazing tool that actually solves problems exceptionally well if trained properly and kept in good condition.

_________________
_____________
Conny Forsberg


Top
 Profile  
Reply with quote  
 Post subject: Re: Gemologist Lab owners what Tests do u use on Colored Sto
PostPosted: Thu Dec 08, 2016 11:38 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 21602
Location: San Francisco
I have seen so many seasoned professionals mentally site ID an unknown and then bob their heads until their instruments "agree".
I like the German approach. "Let the instruments identify the stone". Once that is done, we can visually determine natural vs synthetic and possible treatments.

The GIA teaches visual ID....I've never agreed with that method.


Top
 Profile  
Reply with quote  
 Post subject: Re: Gemologist Lab owners what Tests do u use on Colored Sto
PostPosted: Fri Dec 09, 2016 12:10 pm 
Offline
Site Admin
User avatar

Joined: Fri Apr 17, 2009 3:53 pm
Posts: 2049
Location: Sweden
If you were referring to me Barbra, I wrote visual inspection, not visual ID... :D

_________________
_____________
Conny Forsberg


Top
 Profile  
Reply with quote  
 Post subject: Re: Gemologist Lab owners what Tests do u use on Colored Sto
PostPosted: Fri Dec 09, 2016 8:05 pm 
Offline
Valued Contributor

Joined: Sat Nov 05, 2016 11:29 am
Posts: 142
Barbra Voltaire wrote:
I have seen so many seasoned professionals mentally site ID an unknown and then bob their heads until their instruments "agree".
I like the German approach. "Let the instruments identify the stone". Once that is done, we can visually determine natural vs synthetic and possible treatments.

The GIA teaches visual ID....I've never agreed with that method.


Excellent wisdom, Barbra!

I recently had a few interesting stones to deal with: At first glance, one looked like a brownish red Garnet, the other an Amethyst...
The refractometer quickly determined the truth: The "Garnet" was really a natural Spinel, and the "Amethyst" was really a Fluorite!
Yes, I can see people having preconceived notions or ideas, but until you test the stone, you really don't know...

-Tom


Top
 Profile  
Reply with quote  
 Post subject: Re: Gemologist Lab owners what Tests do u use on Colored Sto
PostPosted: Fri Dec 09, 2016 8:41 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 21602
Location: San Francisco
Well, thank you Tom.

As Conny said observation is essential. I just give the unknown a spin on the polariscope and a ride on the refractometer BEFORE making an observation. :wink:

Conny is an excellent and experienced gemmo. Top notch.
But I've worked with many gemmos who just use a microscope for ID and are wrong a lot.


Top
 Profile  
Reply with quote  
 Post subject: Re: Gemologist Lab owners what Tests do u use on Colored Sto
PostPosted: Fri Dec 09, 2016 11:23 pm 
Offline
Valued Contributor

Joined: Sat Nov 05, 2016 11:29 am
Posts: 142
Barbra,

I enjoyed that humor! I tend to go to the microscope and the refractometer... The Polariscope is also a great tool, but anomalous double refraction is still bugging me. I need more experience to differentiate between ADR and true DR stones.
I've had fun with the conoscope, going through a small mountain of quartz gems looking for the classic Bullseye patterns.
Need a better microscope, I'm currently using a beater B&L industrial that goes to 30X, but it's just strong enough to *barely* let me into the wonderful world of inclusions in gemstones.
Seeing them is tantalizing, as I'd love to examine them under much stronger magnification to get a better view.
I find I use the dichroscope a bit less than the other tools, and the spectroscope is a favorite of mine.
Of course, once I have followed the easiest path to a conclusive ID, I stop.

-Tom


Top
 Profile  
Reply with quote  
 Post subject: Re: Gemologist Lab owners what Tests do u use on Colored Sto
PostPosted: Tue Dec 20, 2016 11:58 am 
Offline
New to the Forum or The Quiet Type

Joined: Tue Oct 14, 2014 1:18 pm
Posts: 10
Hi calldoug,

It seems you already have some excellent responses here. As a professional gem lab, time may be more critical and testing somewhat more routine. Close observation with either a loupe or microscope will often preclude unnecessary testing and give time-saving clues as to diagnostic features, hardness, possible coatings, or assembled stones.

Raman is my first and preferred ID instrument. When you get a result it is infallible, as it is based on the molecular structure of the material. Experience and further tests confirm whatever detail is required. Observation again plays a role, as assembled materials can sneak up on a hasty gemologist. When Raman is not conclusive, I may try a Raman with a different wavelength laser or go to FTIR, which can identify the mineral group. RI is always an excellent and reliable test, but if I don't have to smell the fumes, so much the better.

There are prescribed ID methods that involve each instrument in a given order, but while this may be helpful for less experienced gemologists, professionals may consider this time wasted. I find the best gemologists follow a path of observation followed by logical steps to eliminate all possible incorrect identifications. This is different for different materials and relies heavily on experience. One has to know what all the possible options are to begin with. If my initial observation reveals curved color banding in a red gem, I only need to confirm that the material is corundum and I am done. Other materials may require every machine in the lab.

With advanced instruments, the mounting is not often an issue other than in some cases of origin determination. There are few parallels between how a person in a professional lab and one using standard gemological equipment such as most appraisers might have, would approach identification, so I don't know that your question serves a good purpose other than to satisfy curiosity. We have a strict policy of only working with industry professionals. On the few occasions this rule was bent, I was invariably argued with and told I was wrong. I wish there was less mystery regarding gemology and how conclusions are reached. Most gemology is based on science, but some is merely opinion. Different labs specialize in different areas.


Top
 Profile  
Reply with quote  
 Post subject: Re: Gemologist Lab owners what Tests do u use on Colored Sto
PostPosted: Tue Dec 20, 2016 10:33 pm 
Offline
Valued Contributor

Joined: Sat Nov 05, 2016 11:29 am
Posts: 142
Cara Williams wrote:
We have a strict policy of only working with industry professionals. On the few occasions this rule was bent, I was invariably argued with and told I was wrong.


Don't you just love that?
I deal with stuff like this way too often, mostly from people inside my industry!
I've gotten to the point where I let people founder in their foolishness.
It's fun to point the finger when everything implodes on them, and say "I told you so".
Folks don't like to take me up on the offer much any more when I say "I'll bet you Lunch that you're wrong"...
And I just love it when non-EE degreed, non-certified people from outside the industry know more than I do after 35 years in the thick of things...


Top
 Profile  
Reply with quote  
 Post subject: Re: Gemologist Lab owners what Tests do u use on Colored Sto
PostPosted: Tue Dec 20, 2016 10:44 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 21602
Location: San Francisco
Cara and Bear are as good as they get!
Their approach is what works best for them and I respect everything they do.....damn, they're good!
I receive odd ball specimens from folks all over the world. For me, it is often more of a mineralogical identification than a gemological one. (I recently got a 4mm faceted eudialite from Russia.)

Regarding Cara's observation, I was once given a "Victorian Mine-cut Diamond Ring" to appraise and when I pointed out the diamond was a princess-cut and the ring was a 14K white gold solitaire with a Stuller maker's marks indicating it was probably 25-30 years old max, I thought this person was going to strangle me, while screaming that I don't know what I'm talking about. (this may be a run on sentence)

"Fair enough madame, no charge. Off you go."


Top
 Profile  
Reply with quote  
 Post subject: Re: Gemologist Lab owners what Tests do u use on Colored Sto
PostPosted: Wed Dec 21, 2016 2:23 am 
Offline
Gold Member

Joined: Thu Apr 17, 2008 1:47 am
Posts: 1350
Location: Pacific Northwest
I got quite adept at explaining the history of flame fusion rubies after countless people brought in their "grandmother's antique ring" to have identified. Many upset and angry people.

_________________
I just dreamed that I was a butterfly.


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 33 posts ]  Go to page 1, 2, 3  Next

All times are UTC - 4 hours


Who is online

Users browsing this forum: No registered users and 6 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
Gemology Style ported to phpBB3 by Christian Bullock