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Who to trust with gemstone identification? Are some gemologists better than others?
  
  Index -> Incorrect classification and fakes
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Adrian August




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PostPosted: Sep 07, 2018 02:09    Post subject: Who to trust with gemstone identification? Are some gemologists better than others?  

Hi to all!

I am rather new to the topic of gems, although I have had certain rocks in the past. I usually tend to trust someone when buying that what they are selling is legit, but from what I have been reading, this is not a very good idea.

My research about so many fakes on the market had me rather concerned, so I googled to find a gemologist in my local area, and took a few stones that I was concerned about in to him.

I was a little perplexed by some of the things that he told me, as it contradicted what I had read online. As a result, I began to wonder who I can trust when it comes to authenticating gemstones.

For example, I have a piece of Citrine that I wanted to make certain was genuine, and not baked Amethyst. When I told him this, he said that baked Amethyst is Citrine, and that all stones are baked anyways, even in the mine themselves and so one can never really know if it has been heated or not. He said that the piece was Citrine though.

He also had a huge geode of Amethyst sitting on his counter that was a few feet tall, and I asked him if it was considered an "A." He said, "I do not know," which puzzled me even more as the retailer at a little local shop was able to point to different pieces and tell me why they were "AA" versus "A" or less. I wondered, if the gemologist does not know, then is he a real gemologist?

As a result, I began to question just how qualified this gemologist was, and who I can really trust when it comes to authenticating a gem?

Are there perhaps different levels of gemologists, some with poor training and others with better training from better places? What do I look for when turning to a gemologist? Are there certain certifications that are better, etc.?

Thanks so much!
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Peter Lemkin




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PostPosted: Sep 07, 2018 02:35    Post subject: Re: Who to trust with gemstone identification? Are some gemologists better than others?  

This Forum is about minerals and rarely about gems per se. You can trust anyone who has been certified by the GIA - Gemological Institute of America [who are then members of the AGA - accredited Gemologists Association], and you can look them up online and get a membership list in your area. GIA also puts out some great, but very expensive, publications for reference.
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John S. White
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PostPosted: Sep 07, 2018 04:26    Post subject: Re: Who to trust with gemstone identification? Are some gemologists better than others?  

Hi Adrian:

Peter's reply was perfect but let me add a few comments. Gemologists do not have a rating system for amethyst geodes using "A"s. In my experience no one does, but I would not be surprised if some retailers use such a system. So I would be inclined to trust the gemologist and not the retailer in this instance. What the gemologist should have told you with respect to the citrine is that most of what you see for sale today is treated, not all is. Naturally colored citrine is rarely seen in rock shops but it exists.

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Bob Harman




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PostPosted: Sep 07, 2018 06:10    Post subject: Re: Who to trust with gemstone identification? Are some gemologists better than others?  

For further completeness, let me add a few comments.

Dealers do indeed use an "A" system for Brazilian and Uruguayan amethyst. The system is based on the saturation of the purple with deep dark color the best or "AAA". Pale or washed out amethyst is rated lowest at "A". Most mid-range examples are "AA". Crystal tip size is also included, but color is most important.

Similar system is in use for Madagascar celestine with ordinary low quality geodes rated "A" and fully saturated larger deeper blue crystals with no or only very minimal damage and large terminated crystals rated "AAA".

Yes, much of the citrine seen today is heat treated, but what has not yet been mentioned is that iron oxide (rusty) stained colorless quartz is also sold as citrine. These examples might be called citrine colored quartz, but are not true citrine. Treatment with a rust (iron) remover will remove or diminish the surface staining, restoring the true colorless quartz. True citrine will not at all have its color changed by iron out treatment. BOB
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marco campos-venuti




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PostPosted: Sep 07, 2018 06:28    Post subject: Re: Who to trust with gemstone identification? Are some gemologists better than others?  

The distinction from natural citrine and heat treated amethyst is possible with expensive test in a high tech laboratory. Because citrine is a cheap stone, dealers assume all citrine in the market are heated for "security reason" because the test is more expensive than the stone.
In Madagascar, Brazil, Congo and also Spain, natural citrine is common in big flawless crystals characterized by a slightly smoky hue from which can be cut inexpensive stones. In contrary heated citrine can show a delightful orange color when the treatment has been carried out professionally. In this case the cost of the treatment and the original amethyst rough is reflected by a price higher than for natural stones. If the heating process is done with a non professional home style, the result is a light yellow inexpensive citrine that can be easily confused for natural.
An other process used is irradiation of amethyst or smoky quartz. Irradiation in theory is the contrary of heating so the black color derived from irradiation is reversible by heating. But this is not always true and in some case a yellow to green color remain. The use of alternate irradiation and heat treatment with different sequences and intensity can produce a large variety of yellow to green colors. Every deposit has a different reaction to the treatment and produce a different type of color.
It is clear that is quite a big job for a gemologist to distinguish every variety. Much simpler is forget the natural ones and consider all as treated.
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John Betts




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PostPosted: Sep 07, 2018 09:06    Post subject: Re: Who to trust with gemstone identification? Are some gemologists better than others?  

Peter Lemkin wrote:
This Forum is about minerals and rarely about gems per se. You can trust anyone who has been certified by the GIA - Gemological Institute of America [who are then members of the AGA - accredited Gemologists Association], and you can look them up online and get a membership list in your area. GIA also puts out some great, but very expensive, publications for reference.


You should look for a gemologist that has "G.G." following their name on their card. This is evidence that they completed the GIA Graduate Gemologist Program.

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John S. White
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PostPosted: Sep 07, 2018 09:56    Post subject: Re: Who to trust with gemstone identification? Are some gemologists better than others?  

In my defense I want to say that the two major dealers in amethyst geodes that I know very well do not use “A” ratings and that is why I was unfamiliar with the usage.
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Josele




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PostPosted: Sep 07, 2018 10:10    Post subject: Re: Who to trust with gemstone identification? Are some gemologists better than others?  

Adrian August wrote:
..., I have a piece of Citrine that I wanted to make certain was genuine, and not baked Amethyst. ...

Adrian, some photos of the "citrine" in question will help to know what we are talking about...
Regards.
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Riccardo Modanesi




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PostPosted: Sep 07, 2018 11:22    Post subject: Re: Who to trust with gemstone identification? Are some gemologists better than others?  

Hi to everybody!
The site parallel to Mindat, whose name is Gemdat, is a specific one for gemstones, as well as GemologyOnLine.com). I think if you visit these sites you can find many interesting thing for you. It's a gemmolgist advicing you it!
Greetings from Italy by Riccardo.

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Hi! I'm a collector of minerals since 1973 and a gemmologist. On Summer I always visit mines and quarries all over Europe looking for minerals! Ok, there is time to tell you much much more! Greetings from Italy by Riccardo.
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Peter Megaw
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PostPosted: Sep 07, 2018 11:47    Post subject: Re: Who to trust with gemstone identification? Are some gemologists better than others?  

I have also seen an even number rating system from 2 (0 being colorless) to 20 (ideal max color...never really reached like an A or B color diamond...system maxes out at 18) with sub-12 generally considered fodder for citrine cooking.

As in all educational programs, there are basic gemologists and advanced or Master gemologists...like BA, MA, PhD.

Also remember, when you're sick and need attention, what you call the person who graduates at the bottom of their class in Medical School...."Doctor"

Here are pictures of a nice natural citrines from Santa Eulalia and Charcas. The one from Santa Eulalia has distinctive sprays or bow-tie bundles of aragonite (X-rayed) and the one from Charcas does not (useful discriminator) Both are skarn deposits, both contain trace amethyst in relatively near proximity, so a natural "ccoking" event is unlikely



2015-09-0193.jpg
 Mineral: Quartz var. Citrine
 Locality:
San Antonio Mine (San Antonio el Grande Mine), East Camp, Santa Eulalia District, Municipio Aquiles Serdán, Chihuahua, Mexico
 Dimensions: 11 x 8 cm
 Description:
Contains distinctive aragonite sprays as inclusions. Jess Scovil image, Peter Megaw specimen (gift from Hector Irigoyen) I wish "San Antonio el Grande" would disappear...it is completely wrong
 Viewed:  1857 Time(s)

2015-09-0193.jpg



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John S. White
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PostPosted: Sep 08, 2018 05:20    Post subject: Re: Who to trust with gemstone identification? Are some gemologists better than others?  

I am fortunate to have a very nice citrine in my quartz collection. As with Peter's, the second of which has yet to appear, my citrine is from Mexico - Level 16, San Bartolo mine, Charcas, San Luis Potosi. The citrine crystals are on danburite, the mineral that Charcas is most famous for.


Quartz - Mexico 11-8-16 (var.citrine on Danburite).JPG
 Description:
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Quartz - Mexico 11-8-16 (var.citrine on Danburite).JPG



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LeadMineGal




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PostPosted: Sep 09, 2018 10:10    Post subject: Re: Who to trust with gemstone identification? Are some gemologists better than others?  

What a stunning piece! Thank you for sharing it!
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