• Long Term Viability of CZ Master Grading Sets

    25 January 2016

    Long Term Viability of CZ Master Grading Sets

    Photographic evidence of the long term viability of cubic zirconia for diamond color grading

    Before we begin this discussion I need to make two points very, very clear.

    1. The following report is only for one CZ Master Set manufacturer, and we offer no guarantee that you will get the same results from all manufacturers, and
    2. The following report is in regards to one CZ Master Set from this one manufacturer, and may not apply to other sets produced by this same manufacturer.

    How's that for a start? Well, it had to be put in here because the use of cubic zirconia master grading sets for diamond color grading is a huge black hole waiting for you to fall in if you don't keep in mind what you are dealing with. You are technically grading apples by using oranges. Perhaps not to that extreme, but pretty darn close. You are grading natural diamond colors using created cubic zirconia with created colors.

    The use of cubic zirconia to grade diamond color has been necessitated by two factors:

    • Master Color Grading Diamond Sets are very expensive and extremely difficult to find on the market these days due to the strict requirements of the American Gem Society Lab, (and the AGSL is the only place I recommend to get your Master Color Grading Diamond Sets graded).
    • Master Color Grading Diamond Sets are very risky to travel with, and a cost effective alternative for home town jewelry appraisers had to be found to minimize the risk.

    As a result of these factors, several companies have been producing cubic zirconia based color grading sets for years. The questions that have been at the forefront of this issue are: Do the cubic zirconia maintain their color? Do the cz colors fade or darken over time?

    Basically, the question is:....What is the long term viability of CZ Master Grading Sets?

    Here in the ISG Gem Lab we have three CZ Color Grading Sets, two of which are from GemOro® and both purchased several years ago. I am not sure of the date but we have had these in the lab for at least 8-10 years, plenty of time for them to fade or do whatever everyone is worried that CZ master color grading sets will do over time.

     

    We also own AGS Master Color Grading Diamond Set #85552-1 purchased several years ago from the Gary W. Wright Company of Phoenix, Arizona. The AGS diamonds come with the approximate Colorimeter number, along with the relative GIA Grading Scale. One of the labels from a diamond from this set is at left. This is a set of four diamonds graded by the AGS Gem Lab and issued the credentials as seen at left.

    Since we have an AGS Master Color Grading Diamond Set, and a GemOro"The Master Set"® of cubic zirconia that is at least 8 years old, it is quite easy to line them up side by side and test to see if the GemOro cz set still accurately holds its master color grading colors.

    I should first tell you that photographing diamonds for color grading comparison is about as difficult as it gets. Fortunately, with our Meiji Techno GEMZ-5 microscope I was able to get a pretty accurate depiction of the color comparisons of these two sets. Yes, there are some minor variations, but in real life these two sets are about as spot-on for comparison as you would hope to get from a CZ Master Color Set to an authentic AGS Color Grading Diamond Set. Below are the comparison images:
    ISG CZ
    These were adjusted some in Photoshop for brightness and contrast, but the colors you see are very accurate to the actual comparison through the Meiji Techno. And remember that the AGS Master Color Grading Diamond Set is based on Colorimeter readings so the actual GIA Nomenclature grade can vary some, which is the reason for the split grades. We go into that further in the ISG Diamonds Course, but for now I can only tell you that our GemOro set of CZ Masters continue to hold their accurate grading colors after all these years.
    If you own a CZ Master Grading Set, just remember to keep it covered up when not in use, just like I have always done with the set above. It is suspected that ambient UV radiation from things like sunlight and fluorescent lights can cause the CZ sets to fade or alter in color. By always closing the lid and keeping the set in darkness when not in use you will most likely get years of use from your set, as we have done here at the ISG office.
    Final Recommendation
    My final recommendation for you to maintain the accuracy of your diamond grading with a CZ Master Set is to find someone with an AGS Master Color Grading Diamond Set and occasionally compare your cz set to the master diamond set. This will assure you and your clients that your diamond color grading is as accurate as possible through the use of the CZ Master Set...until you can find (or perhaps can afford) to buy an AGS Master Color Grading Diamond Set.

    So regarding our original question: What is the long term viability of CZ Master Grading Sets?

    The long term viability of CZ Master Sets can be very good if you take proper care of them, and have them tested along-side a Master Color Grading Diamond Set from time to time.

    Hope this has helped those of you out there worried about affording a diamond set. The CZ set can be a viable alternative.

    Robert James FGA, GG
    President, International School of Gemology

    If you would like to learn more about our world-class study in gemology and jewelry appraisal, click the link below. And don't forget to come visit us at the AGTA GemFair Tools and Technology Pavilion starting on 2 February, Booth 211
     
    ©2016 YourGemologist LLC and the ISG. ALL RIGHTS RESERVED. We encourage sharing and caring throughout the industry as long as all copyrights are left intact. The GemOro name and images are used for comparison and study, and remain the property of GemOro.