Education for Certificates - DiamondHouseAZ.com

A diamond certificate or diamond grading report is an evaluation of your diamonds’ characteristics. Gemologists have created diamond grading laboratories to provide a third party evaluation for the diamond industry’s demand of certificates. Gemologists utilize modern technical tools to distinguish a diamond’s characteristics. Many diamond grading laboratories utilize several independent gemologists’ evaluations of a diamond and compare them before the certificate is complete. If there are discrepancies between the gemologists’ determinations, another gemologist or team of gemologists may be required before a common agreement can be reached concerning the quality of a diamond, and before a certificate can be issued.

The following is a list and brief description of diamond characteristics that you may find on a diamond certificate.

Gemological Laboratory Name:
The name of the laboratory that is issuing the diamond certificate/grading report.

Certificate Reference Number/Report #:
The diamond certificate/grading report number specific to a particular diamond.

Date:
The date a diamond certificate/grading report was completed.

Shape and Cutting Style:
The shape of a diamond.

Weight:
The weight of a diamond in carats.

Color:
The color grade of a diamond.

Clarity:
The clarity grade of a diamond.

Dimensions/measurements:
The length, width and depth of a diamond in millimeters.

Table:
The proportions of a diamond as it relates to the
table percentage.

Depth:
The proportions of a diamond as it relates to the depth percentage.

Crown:
The proportions of a diamond as it relates to the crown
height percentage.

Pavilion:
The proportions of a diamond as it relates to the pavilion depth percentage.

Girdle:
A description of the characteristics of the girdle of a diamond.

Culet:
A description of the characteristics of the culet of a diamond

Polish:
A grade performed by a gemologist or team of gemologists that describes how well a diamond is polished.

Symmetry:
A grade performed by a gemologist or team of
gemologists that describes how proportionate the crown and pavilion are on a diamond as well as the degree to which the culet is centered underneath the table.

Fluorescence:
Some diamonds contain fluorescence. It is preferred that a diamond with a color grade of D – H have the following fluorescent grades: none, faint blue, very slight blue or slight blue. Any stronger degree of fluorescence than these will retract from how light refracts off your diamond and will, therefore, not be as brilliant. However, stronger fluorescent grades, such as moderate blue, strong blue, and distinct blue, in diamonds that have a color grade of I – M, are sometimes preferred because the stronger fluorescence detracts from the yellowish tints of these diamonds.

Cut Grade:
A grade performed by a gemologist or team of gemologists that describes how well the overall proportions of a round brilliant cut diamond are using the following characteristics: total depth, table size, crown angle, pavilion angle, star length, lower-half (lower-girdle facet) length,
girdle thickness, and culet size, as well as the diamond's polish and symmetry grades.

Inscription:
A laser inscription can be found on the girdle of a diamond. This can help identify a specific diamond.

Comments:
Any additional notes a gemologist or team of gemologists believe is prudent to the diamond.

Inclusion Plot Diagram with Key to Symbols: A diagram of the shape of the diamond presented on the diamond certificate/grading report with a plot of where the inclusions are located on a specific diamond as well as the type of inclusions on a specific diamond. A Key to Symbols is similar to that of a legend on a map. It will define the types of inclusions plotted on the Inclusion Plot Diagram.

It is Diamond House’s recommendation that, when comparing diamond prices of diamonds of similar qualities, consumers consider all the characteristics mentioned on a diamond certificate in order to make a sound decision. This way, consumers can shop items “apples for apples” rather than “apples for pears”. This also applies when you compare diamonds that were graded by different Laboratories. For example, if I am looking at a diamond certified by the Gemological Laboratory of America (GIA), I should be comparing it against other diamonds certified by GIA as well. At the Diamond House, you will find diamonds graded by the European Gemological Laboratory (EGL), the European Gemological Laboratory United States (EGL US ), the American Gem Society (AGS) and the Gemological Institute of America (GIA). AGS and GIA have set the standard in the diamond industry as being the most credible in their grading techniques and standards. EGL and EGL US are seen in the industry as being more lenient in their grading. In spite of this, EGL US ’ reputation has improved more recently even though its grading standards still seem to be more lenient than GIA and AGS.

Look to the sample certificates below to see the differences and similarities between them.

GIA	AGS	EGL	EGL-USA

Certificates are not appraisals. An appraisal is a replacement evaluation document that determines the retail value of a consumer’s diamond. As soon as a diamond is purchased, a consumer should contact their insurance company and give them a copy of their appraisal so that it may be insured against loss or theft. Each diamond purchase at the Diamond House includes a certificate (if noted) and an appraisal.