Grading Emeralds
AZemerald Colombian Emeralds uses American Gemological Laboratories (AGL) exclusively for all our emerald grading reports. You can view their website at http://www.aglgemlab.com. I think their grading reports are easier for a consumer to understand than the GIA or AGTA reports. Many experts feel the AGL reports are by far the best in the industry for colored stones. A report from any of the three labs is almost a necessity when buying high-end emeralds, sapphires, or rubies. Do not trust any gemstone dealer including myself about emerald treatments or grading without a lab report. The fact is most dealers have no idea what treatments were performed on an emerald before they purchased it and if they do it still needs to be proven. A third party laboratory like AGL takes all the guesswork out of the equation and provides confidence for the consumer and FTC compliant enhancement disclosures. They also prohibit any conflict of interest on the part of the seller. Now just because a gemstone you are interested in has a gem report doesn’t mean that it goes into much depth. All the laboratories have different tiers of reports starting with whether the stone is natural or not. This is the least expensive report and is useful for emeralds and other gemstones that are not very expensive. But a report that says “natural green emerald” is not enough information to go on when you purchase an emerald for thousands of dollars. The next tier report includes grading of color, clarity, and degree of enhancement. This type of report has all the information you need to buy mid to high-end Colombian emeralds. These reports allow you to compare the quality of one Colombian emerald verses another. This is the report we get for most of our emeralds for sale. The next tier of report will include locality along with the color and clarity grading. This report is particularly important when locality greatly affects the price of the gem and is difficult to determine such as Burmese rubies. Colombian emeralds are fairly easy to identify from Brazilian and Zambian emeralds because of their unique color and inclusions. Finally the last tier of report will go into a higher detail of grading and will identify specific treatments that may have been used on the stone. These reports are not cheap and are usually reserved for exceptional untreated emeralds and other gemstones.
AGL has these four tiers of reports starting with the Fast Track I, Fast Track II, Fast Track Premium, and the Prestige Report. As a general rule I will use each service according to the follow price points per emerald.
Under $500 Fast Track I
$500 to $2500 Fast Track II
$2500 to $5000 Fast Track Premium
Over $5000 Prestige report
AGL’s description on how to interpret the Prestige Report can be found at
http://www.aglgemlab.com/prestige.html
An explanation of the Fast Track services can be found at
http://www.aglgemlab.com/fasttrack.html
The Fast Track reports are based on the original Prestige Reports but use a written description rather than a numerical one making the grading scale a little broader (more like a 5 point scale rather than a 10 point scale). Let’s look at one in detail
How to Interpret an AGL Lab Report
Date: Date of report
Identification: Natural Emerald (locality is specified in FastTrack Premium)
Measurements: Accurate to one hundredth of a millimeter presented as length x width x height
Carat Weight: Accurate to one hundredth of a Carat
Shape/Style: Shape of cut (Emerald Cut, Oval Mixed Cut, ect.)
Color/Tone:
Color grades include:
Excellent (Equivalent to 1-2 on Prestige)
Very Good (Equivalent to 3-4 on Prestige)
Good (Equivalent to 5-6 on Prestige)
Fair (Equivalent to 7-8 on Prestige)
Poor (Equivalent to 9-10 on Prestige)
Tone grades include:
Very Light (0-20)
Light (25-35)
Light-Medium (40-50)
Medium (55-65)
Medium-Dark (70-85)
Dark-Very Dark (90-100)
Clarity:
Clarity grades include:
Free of Inclusions (Equivalent to FI on Prestige)
Lightly Included (Incorporates both LI1 and LI2)
Moderately Included (Incorporates both MI1 and MI2)
Highly Included (Incorporates HI1, and HI2)
Excessively Included (Incorporates EI1, EI2, and E13)
Cutting:
Cutting grades include:
Excellent (Equivalent to 1 on Prestige)
Very Good (Equivalent to 2-3 on Prestige)
Good (Equivalent to 4-6 on Prestige)
Fair (Equivalent to 7-8 on Prestige)
Poor (Equivalent to 9-10 on Prestige)
Standard Enhancement
Enhancement grades for emeralds include:
None
Not significant
Faint
Faint to moderate
Moderate
Moderate to strong
Strong
Strong to prominent
Prominent
Enhancement Type
For emeralds the following types are:
Oil
Wax
Polymer
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