How to Evaluate a Diamond Grading Certificate

Step-by-Step Guide

1. 1

   Step 1: Understand that some companies call their reports "certificates" when they aren't.

   Many laboratories call their documents "certificates"; however, this can be misleading to a consumer.
   
   If you read the back of these documents, even the ones that print "certificate" on them, the fine print on the back states that they only "certify" that a gemologist or several gemologists have graded the diamond.
   
   They also state that the report is "no guarantee"
   
   and therefore, by definition, does not certify the quality that they are documenting.
   
   The only retail establishment using an ISO laboratory that actually issues a certificate is Tiffany & Co.
   
   They do certify and guarantee the quality of their diamonds.
2. 2

   Step 2: Recognize a report provided by HRD.

   Hoge Raad voor Diamant (HRD), or "Diamond High Council," is Europe's counterpart to the GIA.
   
   HRD's grading certificates are legal documents in the eyes of the European Union. , The Precision Gem Grading Laboratory (PGGL) in Philadelphia, PA, uses ImaGem's Direct Measurement technology for objective diamond grading.
   
   ImaGem's technology grades diamonds based on measurement of color, clarity, fluorescence and light behavior.
   
   They have the capability to support all grades with numerical measurements. , The International Gemological Institute (IGI) mostly conducts appraisals for diamond engagement rings. , The American Gem Society (AGS) grades and evaluates diamonds based on their cut grade from 0 (most desirable) to 4 (least desirable). , The Gemological Institute of America (GIA) is a non-profit institute that created the "four Cs" (Cut, Clarity, Color and Carat Weight) methodology of grading diamonds, as well as the International Diamond Grading System.
   
   However, reports from this institute omit certain aspects of diamond cuts that other reports cover (e.g. crown height percentage, pavilion depth percentage, crown angle, pavilion angle).
   
   Reports from the GIA after 2005 that are full Diamond Grading Reports (they do not use the word "certificate") include the diagram and proportions of the diamond's cut. , The European Gemological Laboratory (EGL) is an independent network of diamond grading laboratories.
   
   EGL laboratories use GIA nomenclature, but their master grading diamonds do not necessarily match those used by the GIA, nor does their lighting and grading methods..
   
   Therefore, diamond certificates from the EGL are generally less reliable than those from the GIA., This is the most vital information to determine, as it summarizes the beauty of the stone.
   
   The cut determines how the light reflects and refracts through the diamond to make it dance and dazzle. , To know how well a diamond has been cut, make sure the document grades the gem's cut or light behavior based on direct measurement.
   
   Beware of labs that list cut grades based on a model, and not the actual diamond. , The diamond grading report should have measures for brilliance, fire (spectral colors), sparkle and pattern.
   
   It should also include polish and finish (craftsmanship) notations.
   
   If it does not, you have the right to ask your jeweler for an independent light behavior grading certificate. , A diamond grading certificate only details the gem's properties at the time of inspection, so it means virtually nothing if the diamond was altered afterwards. , The older the certificate, the greater the chance that the diamond has been altered (e.g. set or worn). , If the document is over a year old or has no date, you can ask the gemologist to verify the report or pay to send it in for re-examination.
   
   If this is not possible, at least ask about the diamond's history and inspect the stone under a scope for abrasions on the crown (top), culet (bottom), or at around its girdle (the narrow band around the outer circumference of a diamond, where it is held by the jewelry setting). , One carat is equal to 1/142 of an ounce.
   
   Generally, the higher the carat weight, the higher the price; however, prices leap at certain weights, and some weights are more popular (and thus more expensive) than others. , The diamond weight is an exact measurement usually to the second decimal.
   
   It is one way to verify the report.
   
   It is important to note that the carat weight is a volume weight, not the visual size of the diamond.
   
   It is possible for a .97 carat diamond to be wider than a
   1.03 carat diamond. , Grading reports list a maximum and minimum diameter for round diamonds, since no diamond is perfect.
   
   The difference between these two diameters is indication of how good the proportions are in a round diamond.
   
   For example, a round diamond with a measurement of
   6.50 x
   6.56 x
   4.72 mm may have a diameter that varies by
   0.06 mm.
   
   This number is the difference between the first two measurements listed. , A list of the average diameter tolerances for variances is:
   0.5 carat
   -
   0.05 mm
   0.6 carat
   -
   0.06 mm
   0.7 carat
   -
   0.07 mm
   0.8 carat
   -
   0.08 mm
   0.9 carat
   -
   0.09 mm
   1.0 carat
   -
   0.10 mm
   2.0 carat
   -
   0.12 mm
   3.0 carat
   -
   0.14 mm
   4.0 carat
   -
   0.16 mm
   5.0 carat
   -
   0.17 mm This is a suggested industry reference; fancy shape preferences are as individual as diamonds are. , For fancy shapes, divide the diamond's length by its width to determine the ratio.
   
   If your answer is
   1.8, for example, then the ratio is
   1.8:1. , A list of the average ratios for fancily-shaped diamonds are:
   Pear
   -
   1.50:1 to
   1.75:1 Marquise
   -
   1.80:1 to
   2.20:1 Emerald
   -
   1.30:1 to
   1.50:1 Princess
   -
   1.15:1 to
   1.00:1 Radiant
   -
   1.50:1 to
   1.75:1 Heart
   -
   1.25:1 to
   1.50:1 Oval
   -
   1.30:1 to
   1.50:1 , Consult the organization that produced the certificate for information on what each clarity measurement means. , The clarity ratings for the GIA are listed here as an example:
   FL = Flawless.
   
   No internal inclusions or external irregularities visible under 10x magnification to a trained eye.
   
   IF = Internally Flawless.
   
   No internal inclusions but possibly tiny external irregularities in the finish visible to trained eye under 10x magnification.
   
   VVS-1 = Very Very Slightly Included
   1.
   
   Usually one very tiny inclusion visible only to a trained eye under 10x magnification.
   
   VVS-2 = Very Very Slightly Included
   2.
   
   Tiny inclusions visible only to a trained eye under 10x magnification.
   
   VS-1 = Very Slightly Included
   1.
   
   Some very small inclusions visible to anyone with 10x magnification.
   
   VS-2 = Very Slightly Included
   2.
   
   Several very small inclusions visible to anyone with 10x magnification.
   
   SI-1 = Slightly Included
   1.
   
   Small inclusions visible to anyone with 10x magnification.
   
   SI-2 = Slightly Included
   2.
   
   Several small inclusions visible to anyone with 10x magnification.
   
   SI-3 = Slightly Included
   3.
   
   Inclusions are visible to the naked eye of a trained observer.
   
   I-1 = Included
   1.
   
   Flaws that are visible to the naked, untrained eye.
   
   I-2 = Included
   2.
   
   Many flaws clearly visible to the naked, untrained eye that decrease the diamond's brilliance.
   
   I-3 = Included
   3.
   
   Many flaws clearly visible to the naked, untrained eye that decrease brilliance and compromise structure, making the diamond vulnerable to cracking or chipping. , As a rule, colorless diamonds are more expensive and desirable than yellow or brown diamonds. , Natural blue, green, pink, red and some yellow diamonds may also increase or decrease in value depending on market demand.
   
   Diamonds that have enough concentration of color and graded as fancy by a laboratory generally have a greater value, depending on the market and their grading factors, since they occur more rarely in nature. , This often negatively impacts the market value.Diamonds with brown or grey overtones can be cut beautifully, however, and that can mask their slight body color.
   
   They offer a lower price due to color, but they can be just as brilliant
   - although warmer looking.
   
   Be aware, if the price is too good for the size, look at the diamond next to a white, lighted background. , Depth refers to the total depth of a diamond from table to culet, as a percentage of its total diameter.
   
   The desired depth percentage depends on the shape of the diamond.
   
   Well-cut round diamonds usually are around 59%-62%. , Culet refers to the bottom of a diamond that ends in a point.
   
   It may be faceted to protect the fragile tip from chipping. , Table refers to the width of the largest top facet of a diamond.
   
   The table percentage is the averaged measurements of the table, as a percentage of the total average diameter of the diamond.
   
   Table percentages of a well proportioned modern round brilliant cut diamond range from 52%
   - 62%. , Girdle refers to the area of the diamond where the bottom meets the top of the diamond.
   
   It may be rough, bruted, bearded, polished or faceted.
   
   It is also the area most likely to have naturals, nicks, chips and cavities , Before buying a diamond, be sure its certificate lists each of the following finish qualities as "good" or better, and that the grading characteristics of "polish" and "symmetry" are at least "good" or better:
   Polish Symmetry Fluorescence Opinions vary on the desirability of fluorescence in a diamond.
   
   Strong fluorescence in slightly yellow diamonds may make them appear whiter, but strong fluorescence in white or fancy colored diamonds is generally less desirable.
   
   Any amount of fluorescence may affect the value. , On some diamond grading reports, the finish section details other characteristics of the stone not covered by the general report, like external grain lines or inscriptions.
3. 3

   Step 3: Spot a report by the PGGL.

4. 4

   Step 4: Identify a grading done by the IGI.

5. 5

   Step 5: Look for a grading from the AGS.

6. 6

   Step 6: Check for a grading from the GIA.

7. 7

   Step 7: Notice a report from the EGL.

8. 8

   Step 8: Understand the importance of a diamond's cut.

9. 9

   Step 9: Check the document's grading of the diamond's cut.

10. 10

    Step 10: Make sure the grading certificate includes light behavior grades and numerical measures for brilliance

11. 11

    Step 11: sparkle and intensity.

12. 12

    Step 12: Ensure that you check the date of the document.

13. 13

    Step 13: Understand that an old report may be meaningless.

14. 14

    Step 14: Arrange for a verification.

15. 15

    Step 15: Know how much a carat weighs.

16. 16

    Step 16: Understand that the diamond weight should be fairly accurate.

17. 17

    Step 17: Recognize the importance of the diameter.

18. 18

    Step 18: Know the standard diameter variances for round diamonds.

19. 19

    Step 19: Do some basic math to determine measurement ratio.

20. 20

    Step 20: Inform yourself about the standard ratios for fancy shapes.

21. 21

    Step 21: Acknowledge that clarity grading systems vary.

22. 22

    Step 22: Use an example system if you're unsure.

23. 23

    Step 23: Know that each lab has its own color grading system to differentiate diamond hues.

24. 24

    Step 24: Understand that the value of colored diamonds will fluctuate.

25. 25

    Step 25: Avoid diamonds with brown or grey overtones.

26. 26

    Step 26: Understand what "depth" is.

27. 27

    Step 27: Learn what "culet" refers to.

28. 28

    Step 28: Know what the "table" is.

29. 29

    Step 29: Recognize what "girdle" is.

30. 30

    Step 30: Check the "finish" qualities.

31. 31

    Step 31: Know that not all reports are the same.

Detailed Guide

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