Certificates and how to read them

How to read a certificate

The GIA Coloured Diamond Grading Report contains the following information:

• Date: The date that the diamond was examined by the GIA and the report was issued.
• GIA Report Number: The unique tracking number assigned to each diamond and report. Sometimes this number is laser inscribed on the girdle of the diamond. If so, this will be mentioned in the comment section of the report.
• Shape and Cutting Style: (e.g. Round Brilliant, Cut-Cornered Rectangular Modified Brilliant, etc.) 
• Measurements: The length, width and depth of a diamond, expressed in millimetres to the nearest one hundredth of a millimetre.
• Carat weight: The weight of a diamond is measured in metric carats, abbreviated as ct(s) and is divided into 100 points.
• Colour Origin: States if the colour of the diamond is natural or a result of a treatment. If the colour is enhanced or otherwise artificially treated, the treatment will be disclosed under the comment section at the bottom of the certificate.
• Colour Grade: Describes the combined effect of tone and saturation in color and is expressed in terms like Faint, Light, Very Light, Fancy, Fancy Light, etc.
• Distribution: Describes the evenness of the color.
• Clarity Grade: Clarity is a gemstone’s relative freedom from clarity characteristics, which are known as blemishes and inclusions.  
• Finish: A diamond’s final detailing, its finish is made up of two qualities: polish and symmetry.
• Polish Grade: The overall condition of the facet surfaces of a finished diamond.
• Symmetry: The precision and balance of a finished gem’s cut. This includes the exactness of the proportions and the balanced placement of the diamond’s facets from one side to another.
• Fluorescence: The emission of visible light by a material when it is exposed to ultraviolet radiation (like a ‘black light’ for example). 
• Comments: Additional clarity characteristics that are too minor to be reflected in the plot are mentioned in this section. Between the comments section and the plot, all inclusions, visible under a 10X magnification are accounted for. Furthermore, if the girdle is ‘painted’, ‘digged out’ , bearded, polished/ faceted or laser inscribed, this will be mentioned in the comments section as well.

REFERENCE DIAGRAMS

The reference diagrams include the Plot and the Proportion Diagram. The Key to Symbols is located below the plotting diagrams and lists the characteristics and symbols shown on the plotting diagrams.

• Diamond Plot: A plot is a graphic map of the clarity characteristics -visible under 10X magnification- of a diamond and is used to document the condition of the stone, support and explain the clarity grade and to identify the stone.

At the right of the plotting diagram is the proportion diagram located. This is a representation of the diamond’s proportions.

• Diamond Proportions: A diamonds’ proportions are the angles and relative measurements and the relationship between them. The proportions are graphically represented in the proportions diagram.
• Table Percentage: The table percentage of a diamond is calculated by expressing the average table diameter as a percentage of the average girdle (the outline) diameter.
• Total Depth Percentage: The total depth percentage of a round brilliant is its table-to-culet depth, expressed as a percentage of its average girdle diameter.
• Girdle Thickness:  The function of the girdle is to prevent damage and providing an edge for setting the stone into jewellery.

• Culet Size: The culet is the small facet at the bottom of a finished gemstone.  In the sample above, the culet is None. This is almost always the assessment.

SCALE REFERENCES

• GIA Clarity Scale:  this scale displays the GIA Clarity grades and their relative positions in the GIA Diamond Grading System.
•  GIA Coloured Diamond Scale: This scale shows the general interrelation of GIA fancy-grade terms, that are used to describe the combined effect of tone and saturation, in colour space.

SECURITY

• Bar Code: The bar code is displayed horizontally on the right-hand side of the report and is used for internal purposes to track the diamond and its progress through the GIA Laboratory during report preparation. This number is different from the GIA Report Number.
• Disclaimer: Beneath the bar code is the GIA disclaimer.
• Security Features: The disclaimer is followed by the GIA hologram. This is one of the numerous security features that ensures that the report is authentic. Other security measurements include micro-print lines, chemical sensitivity and a security screen. 

Certification is often regarded as the “5th C” in addition to Cut, Clarity, Colour and Carat. It provides proof of the value of the diamond to potential investors. The three most reputable gemmological laboratories that issue certificates are the GIA, IGI and HRD. Generally, the GIA-certificate is by far the most preferred in the market, since the GIA has developed many of the scales that are now globally used as the industry standard to grade, appraise and value diamonds.

Founded in 1931, the Gemological Institute of America (GIA) is a non-profit institute dedicated to research and education in the field of gemmology. The GIA is owned by the Mouawad family and has the mission to protect all buyers and sellers of gemstones and maintaining the standards in the industry. The GIA acts as a resource and point of reference in the trade.

The International Gemological Institute (IGI) is a diamond, coloured stone and jewellery certification organisation, established in 1975 with its headquarters in Antwerp. The IGI is the largest independent gemmological laboratory worldwide.

The Hoge Raad voor Diamant (HRD) or High Diamond Council in English was founded in 1973 in Antwerp, Belgium by the Belgian government and diamond industry representatives. The HRD Antwerp is the subsidiary of the Antwerp World Diamond Centre (AWDC) and is one of Europe’s oldest laboratories.

Each Argyle pink diamond of 0.15 carat or above is laser inscribed with a serial number. The Argyle Pink is accompanied by a certificate also guaranteeing its origin and offering an assurance that you are purchasing something truly rare. The diamond will usually have a GIA certificate in addition to the Argyle certificate.  

Verify the authenticity of your diamond certificate by clicking the logo's.

"A little knowledge is dangerous."

- Henri Barguirdjian, President and CEO of Graff Diamonds USA

Kimberley Process Certificate (KPC)

Diffraction Diamonds only sources diamonds that are part of the Kimberley Process, in compliance with the United Nations resolutions and are therefore ‘conflict free’.

Conflict diamonds (also known as blood diamonds), are rough diamonds used by rebel movements to finance war against legitimate governments. The trade in illicit stones has fuelled devastating conflicts in countries such as Angola and Sierra Leone.

The Kimberley Process is a joint governments, industry and civil society initiative to stem the flow of rough conflict diamonds. In December 2000, the United Nations General Assembly adopted a landmark resolution supporting the creation of an international certification scheme for rough diamonds. The Kimberley Process Certification Scheme (KPCS) entered into force in 2003 and was designed to provide a means of certifying diamonds as ‘conflict free’. It imposes extensive requirements on its members to enable them to certify them as such.

The Kimberley Process has not just stemmed the flow of conflict diamonds, it has also help stabilise fragile countries and increase the revenues of poor governments by bringing large volumes of diamonds onto the legal market.

The scheme provides assurance to consumers purchasing diamonds that they are not financing war and human rights abuses.

Since the implementation of the Kimberley Process, conflict diamonds have been reduced to less than 1% of the trade. Today, the diamond revenue is instrumental in the development of African countries, contributing to education, health care, financial and economic sectors of African countries.

Learn more about conflict diamonds and the Kimberley Process in our Diffraction Article.

“The diamond industry is vital to the southern African economy”

- Nelson Mandela, 17th November 1999