CIBJO releases Gemmological Special Report: considers process of separating measurable facts from opinion; See Gemological Articles below.
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PostPosted: Mon Jan 29, 2007 3:14 pm 
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Good question. It reminded me that I've read someplace that for color to be accurate masters must be meticulously cleaned (in acid?) periodically. After 38 years this might be even more important. So maybe in a way the stones do change :).


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PostPosted: Mon Jan 29, 2007 6:26 pm 
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Hi Carrie! Thanks for the welcome. In reference to your question about older masterstones, I think you can place your mind at ease. The original set of masterstones was compiled by GIA in the 1950s and per GIA, since then "additional masterstone sets have been assembled by carefully matching them to the original set."

Also as the post previous to this one mentioned, GIA does acid clean their teaching diamonds OFTEN. I'm not sure how often their original masterstone set is cleaned however. I doubt it needs it frequently as any handling of the stones is most likely done with gem tweezers. As for purchasing an older set though, it might be a good idea. :D


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 Post subject: Master set
PostPosted: Mon Feb 26, 2007 1:35 pm 
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I have 12 stones in my diamond master set.
a] ONE extra for grins....... z grade si1 30 pointer =$100
PINK, GREEN, chatham canary asher cut .33 ct= $250
b] all under .30 ct each at least si1 and above, mostly splits, one d-F
GIA Master set includes: 6 STONES
3 splits, round brilliants, .30 max size, 6 stones, registered
.26 CT F-G
.298 CT I-J
.261 CT K-L
.281 CT M
.307 CT T
.30 CT D
GENERICS FANCIES IN COLOR HUES ROUGHS, MACLES, ALLUVIALS, USA
PLUS SOME AUSTRALIAN CHAMPAIGNS 4 ALL .40 FANCIES, DRILLED BEADS, BLACK DIAMONDS, CAMILLION 5 CT BRAZILIAN OVAL


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 Post subject: cz SETS TO GRADE cz'S
PostPosted: Mon Feb 26, 2007 1:45 pm 
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I also have CZ master sets to grade CZ's both for cut and color. I do not use these for diamonds. Cutting quality, meet point, color, and finish
is very different in the makes of CZ. Not all stones are the same!
I have 4 grades of mille samples for each gem type, species, and variety. We are trying to get similar samples of rough to add to our collection. Gemstones from different mines for fine,
good, commercial, and declasse.
We designed tables of stones of price lists and compare one list with another to see if they are using the same standards of quality control.
Not all lists agree, some place stones higher and some lower.
Proportion grading follows American Facetor's guild guidelines and GIA
cut grade which is much lower than AFG standards.
We also working on an antique diamond master set, for antique jewelry items those stones are at least .50 ct each.


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 Post subject: Re: Master stones...
PostPosted: Fri Mar 13, 2015 10:55 am 
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Hello!

I have been reading this old thread with keen interest and as I am new to the industry practically, book nerd *tick*, hands on experience zero, I would LOVE to hear from you experienced peeps!

What is the verdict today? In 2015?
Who does the best CZ Master Set nowadays?
Ellen vs GemOro CZ Master set?? Or who's new? =D>

:?:


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 Post subject: Re: Master stones...
PostPosted: Fri Jan 27, 2017 12:13 pm 
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This is a great article and update on this subject worthy of reading.
It is from ISG, International School of Gemology...

https://www.evernote.com/shard/s33/sh/4 ... 0a2a6837d5


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 Post subject: Re: Master stones...
PostPosted: Wed Mar 13, 2019 12:09 pm 
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Hi everyone!

Hope all is well :) . This is my first time on the forum, but I’ve been following it for quite some time. I’m sorry for asking a question on an old topic, but I just wanted to know if anyone has any recommendations on what size master stones I should go for? I would like to slowly start building up my diamond master stones set as I would like to open a one person gem lab eventually. I know they have to be 0.25cts or bigger, but what is the best size to accurately grade color without breaking the bank.

I would really appreciate any recommendations.


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 Post subject: Re: Master stones...
PostPosted: Tue Mar 19, 2019 9:39 pm 
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Hi, Mel -
I have had a lot of luck with my master stones. They are all around 0.40ct each. If you can afford to buy 2 or 3 stones at once to start out - that is what I would recommend. It does take some time to get them graded and hopefully with luck - approved as master stones by GIA. However, the CA lab was extremely helpful and pleasant to work with when I was adding a fifth stone to my set. I think I ended up having to send in three stones (all with prior GIA lab report's color grade of H) until one was found to be right in the middle of the "H" color zone and thus acceptable to serve as a master stone.
Best wishes!
Katy B


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 Post subject: Re: Master stones...
PostPosted: Wed Mar 20, 2019 12:31 am 
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Hi Katy B,

Thank you so much for taking the time and effort to reply. I’m truly so grateful. It was extremely helpful. I did buy CZ master stones for now for jewelry appraisals until I can afford the diamond masters. At least now I have a size bracket that I can work with thanks to your assistance.

Once again thank you so much! :)

Have a wonderful day further!


Kind regards,

Melissa


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 Post subject: Re: Master stones...
PostPosted: Wed Mar 20, 2019 1:28 am 
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Katy,

Just to be sure you are using the master stones correctly, I feel I should point out that a GIA master stone does not represent the middle of the color range. A master stone represents the highest color in it's named range. So if you have a master stone labeled "H", any stone the slightest bit less tinted is a "G". Therefore a stone that is more tinted than the "H" master, and less tinted than the "I" master is an "H".


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 Post subject: Re: Master stones...
PostPosted: Wed Mar 20, 2019 10:08 pm 
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Oh goodness, thank you for the important reminder about where the master stones fall and what they represent in the specific color grades.
I appreciate it!
Best wishes,
Katy B

P.S. To Melissa - I didn't know any diamond brokers at the time and had great luck working with Blue Nile directly in searching for a diamond that might work with my master stones. I'm sure that there are others out there - just be up-front and tell the representative who you are and what you are trying to do and ask if they would be willing to work with you through the process.


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 Post subject: Re: Master stones...
PostPosted: Wed Mar 20, 2019 10:53 pm 
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I think the possibility of putting together affordable master sets from lab grown diamonds is getting good.

The problem with using lab grown diamonds as master stones in the past has been that like CZ the tints are off to the brown/grey rather than yellow like natural stones. This having to interpolate between the colors greatly reduced the usefulness of both as master stones.

However, there is now a lab grown diamond company in Russia that is able to make yellow (cape series) tinted stones reliably. I have seen a reasonable number of these stones and I believe they should work perfectly. Fingers crossed that this developes.

This company can also make blue tinted stones. I had the pleasure of see stones with subtle blue tints in the G,H,I, tones and they were incredibly beautiful. Of course when grading such a stone you would know right away it was lab grown so for some the apeal is limited.

Good things coming....


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 Post subject: Re: Master stones...
PostPosted: Thu Mar 21, 2019 2:16 am 
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Thank you so much to everyone for the help- especially Katy B and 1bwaba1. This info will definitely help me and point me in the right direction 8)

Hope I can also help someone else out in future.

You all have a wonderful day! :D


Best regards,

Melissa


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