Diamond Education – GIA certificated diamonds

round brilliant cut diamond

Round Brilliant Cut Diamond

princess cut diamond

Princess cut diamonds

emerald diamond

Emerald cut diamonds

marquise diamond shape

Marquise diamond cut

pear diamond shape

Pear cut diamonds

oval diamond shape

Oval cut diamonds

heart diamond shape

Heart shape diamonds

Asher cut diamond

Asscher cut diamonds

THE FOUR C’s of a Diamond

Carat Weight: Refers to the standard unit of weight for diamonds and other gemstones. Carat weight is measured at the GIA Laboratory using a highly precise electronic scale, rounded to the nearest hundredth of a carat.
Diamond carat-weight

Colour: Refers to the GIA Colour Scale, which extends from D (colourless) to Z (light yellow or brown). Colour grades are established by comparing each diamond to a set of master comparison diamonds in a standard lighting and viewing environment. Each letter grade represents a range of colour.

Diamond colour

Clarity: Refers to internal features (inclusions) and surface characteristics (blemishes) within or on a diamond when viewed with 10x magnification under standard viewing conditions. The GIA Clarity Scale includes eleven clarity grades from Flawles to l3.

Diamond clarity

Cut: Refers to how the proportions and finish of a diamond affect it’s overall appearance and quality. Cut is graded on a scale from Excellent to poor and incorporates the diamond’s brightness, fire, scintillation,weight ratio, durability,polish and symmetry.GIA only produces a cut quality grade for standard round brilliant diamonds that fall within the GIA O-Z colour range.

Diamond cut, hatton garden jewellers

Proportions: Refers to a polished diamond’s dimensions, facet angles and the relationships between them. For standard round brilliant diamonds, GIA reports the measurements of eight proportions: see diagram. For fancy shape diamonds (those other than standard round brilliants). GIA reports measured values for table size are girdle thickness and culet size are reported with word descriptions based on visual assessments.

Finish: Refers to the quality of a diamonds polish (the overall condition or smoothness of it’s surface) and the symmetry (exactness of it’s outline and the shape,placement and alignment of it’s facets). Polish and symmetry are visually assessed and grade in one of the following categories: Excellent, Very Good, Good, Fair And Poor.

Fluorescence: Refers to the emissions of visible light from a diamond when subjected to ultraviolet radiation. On GIA Diamond Reports, fluorescence is a description not a grade. The terms for describing the strength of fluorescence are: None, Faint, Medium, Strong and Very Strong. For Medium, Strong and Very Strong fluorescence, the colour of the fluorescence will also be noted.

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GIA Guide to Understanding 4Cs of Diamond Quality | GIA Diamond Grading Reports

How to Buy a Diamond Guide >> click here

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GIA’s International Diamond Grading System

In 1953 GIA introduced it’s Diamond Grading System, which today has become the international diamond grading standard.
The procedures established by GIA determine the nature of each diamond and asses it’s quality.
The institute only grades natural diamonds and discloses any detected evidence of treatments on it’s Diamond Grading Reports.

Madison  25 Hatton Garden London  EC1N 8BQ  Phone: 020 7831 8122   alan@madisondiamondrings.co.uk
OPEN: Mon to Sat 9.15am – 5pm and Sun 10.30 – 2pm

We will be closed on Sundays until further notice. Please phone to check current opening hours. 



The National Accociation of Jewellers Diamonds Graded by GIA


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