GIA Diamond Report
is a Diamond Certificate?
Is it better than an appraisal?
The Gemological Institute of America (GIA) established gemstone grading systems that have been adopted internationally. For a fee, GIA's Gem Trade Laboratory will examine and grade any diamond over .23 carat and will disclose its findings in a paper known as a Diamond Grading Report, commonly referred to as a diamond certificate.
For identifying diamonds, or for settling disputes over qualities of particular gems, a GIA Diamond Report is regarded as an impartial arbiter. A Diamond Report is important for insuring any high-quality diamond of a half-carat or more, as it provides a backup to the seller/appraiser's description. However, it is not a substitute for an appraisal because it does not assign value to the diamond, nor does it describe the jewelry as a whole.
Anatomy of the GIA Diamond Report *
The GIA's report contains the following information.
- Report Number. Along the left side is the number uniquely identifying this report in GIA's computer. This number can also be laser-inscribed on the diamond's girdle (see diagram below) to permanently identify the stone.
- Date of the report.
- Shape and Cutting Style. This is the shape into which the gem is cut, such as oval brilliant.
- Measurements. Measurements are given in three dimensions, to the hundredth of a millimeter.
- Weight. Weight is to the hundredth of a carat.
Proportions. Proportions describe the ratio and angles of major physical features of the diamond. Depth and table are given as percentages, girdle and culet are described in a term such as small or medium. (Caution! Important information is missing here. See "What's Left Out" in the next section.)
- Finish. This refers to the quality of the polish and the symmetry of facet placement.
- Clarity. This grade is determined by the number, size, placement and nature of inclusions and/or surface irregularities. The GIA's Clarity Scale appears on the diamond certificate.
- Color. This grade is determined by comparing the diamond with a set of GIA master color comparison stones. The GIA's Color Scale appears on the certificate.
- Fluorescence. Fluorescence (when present) describes the degree of sensitivity of a diamond to long wave ultraviolet radiation, such as is present in daylight.
- Comments. Characteristics not covered above may be listed here.
- A diagram shows the general shape of the stone as seen from the top and from the bottom. The GIA describes the types of internal and external identifying characteristics that are present in the reported diamond (i.e., crystal, needle, and feather). In the diagram, these characteristics are plotted as close to their actual positions as possible. The diagram serves to illustrate the clarity grade, but more importantly it is a basis for the future identification of this diamond.
- The paragraph at the right describes briefly how the stone is examined. It also states that the report is "not a guarantee, valuation or appraisal."
- Logo. Each report contains the GIA GTL company logo and hologram seal. The report is laminated in plastic to protect the report and to guard against tampering.
What's Left Out? CUT!
Cut is one of the "Four Cs" (along with color, clarity. and carat weight) that give diamonds their value. In fact, cut accounts for fully half the value of the diamond. Yet crucial cut information is missing from the report.
What the diamond report gives as "shape and cut" is really just the name of one of the standard shapes into which the raw stone is faceted. Cut as an attribute of value refers to the geometric proportions of the gem. The precision of these proportions affects how the stone refracts light, which is what gives the diamond its brilliance.
Cut comprises three primary measurements. The GIA report lists only one cut proportion, the table. The other two crucial measurements, crown angle and pavilion depth, are omitted.
The report does not give an overall grade for the quality of the cut (as it does for color and clarity). The GIA does have a cut grading system that it uses in-house. However, it deliberately leaves cut grade off the certificate. This is mainly due to political pressures within the diamond industry. Most gems are not properly proportioned; this is done to increase their carat weight, and the industry does not want this to be apparent in the diamond report. (See a discussion of cut proportions for more information.)
Diamond Certificate vs. Appraisal
A Diamond Certificate is a valuable document for the insurer if there is no appraisal or only a perfunctory appraisal. It is a professional, impartial description of the gem, which has very useful information if a claim is ever made.
However, a good appraisal should contain all the information on the GIA certificate. The appraisal will also have valuation, the missing cut information (crown angle and pavilion depth) and a description of the jewelry as a whole (metal, setting, etc.)
Unfortunately, many appraisals do not give cut proportions. That's why insurers should encourage jewelers to use and policyholders to submit the ACORD 78/79 Appraisal, which does include cut proportions.
* This description follows the format of the GIA's new report. Diamond Reports prior to 2000 contain the same information in a slightly different format.
FOR AGENTS & UNDERWRITING
A GIA Diamond Report is a useful document, especially for insuring a diamond valued at more than $2,000. Be sure the submitted certificate is for the diamond being insured. That is, there should also be an appraisal containing the measurements, weight and proportions of the diamond, and these should match the descriptions in the Diamond Report.
Not all diamond certificates are equal. The GIA is a respected organization that has set the internationally accepted standards for diamond grading. Diamond certificates/reports from the American Gem Society (AGS), which we will discuss next month, are also highly regarded. However, some certificates may come from unknown or non-existent organizations or laboratories. Our recommendation is to accept only GIA or AGS diamond reports.
When insuring a diamond of high value, it's best to have both a diamond report (from GIA or AGS) and an ACORD 78/79 appraisal. The appraisal includes all relevant information plus a valuation, while the diamond report gives an independent analysis of the gem's color and clarity grades. (This is worthwhile since color and clarity grades are often inflated; see the November 2000 issue of IM News.)
A GIA Diamond Report, along with the appraisal, is a reliable description for pricing a diamond replacement. Be sure to check that the diamond report is for the same stone described on the appraisal.
Occasionally diamond certificates are forged. If you suspect a forged report, use the report number to verify the report with the GIA. Their number is 760-603-4000. GIA website
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