What are certified Diamonds?

By 23.08 September 20th, 2018 No Comments

Diamond certification is the written proof of a diamond’s attributes. A certified diamond is a polished diamond that comes with a certificate, a grading report of a quality analysis that verifies the specific characteristics of the diamond, viz, colour, clarity, carat and cut, and in some diamonds the level of brilliance (return of light) or flourescence, polish and/or symmetry. Certificates are measured and evaluated by independent gemology organisations such as GIA (Gemological Institute of America), a highly reputable laboratory that is consistent and strict with its grading, IGI (International Gemological Institute), EGL (European Gemological Laboratory) and AGS (American Gem Society) and RGI (Royal Gemological Institute).

It is important for a diamond to be certified so that a buyer knows the quality features of a specific diamond, thus avoiding overpaying for a stone. A certificate issued by a gemology organisation ensures that the authenticity of the diamond is issued by an independent third party, and not by the seller who may be biased. It is wise to pay the high cost of certification for a gem graded diamond that is worth thousands of dollars. Certification verifies that a diamond is 100% natural and not ‘enhanced’, adds value to the diamond, gives an expert third-party opinion, as well as the ability to compare prices. Flawless stones are rare and are consequently very expensive, so an expert assessment of clarity is of paramount importance when choosing diamonds. Always check the seller’s policy to ensure that they only purchase and sell conflict-free diamonds.

Confusion may arise between a certificate and an appraisal, the latter being a document that places a monetary value on gems, compared to the quality features of a certificate. Neither of these are guarantees. Certification gives you information required to assess the market value of a diamond, as well as giving a comparison with other stones. Commercial grade diamonds of small to medium size are generally not certified due to the high cost of this process. These diamonds are still desirable for jewellery items, even though the monetary value is much less than that of gem quality stones.

Grades are assigned to each of the Four Cs characteristics: colour, clarity, carat and cut; these are known as the Language of Diamonds. Each laboratory has different standards for evaluation and levels of detail and each quality stone has a specific inscription, a combination of number and letters, known as a loupe, engraved on the edge of the diamond with a laser. The inscription should match the serial number on the report.


Carat is a measure of a diamond’s weight and thus cannot be disputed. The price rises exponentially with carat weight (one carat of 100 points weighs 0.2 grams). 

Cut is definitive regarding shape and number of facets of the stone. The type of cut is dependent on the buyer’s preference as there are many variables, some of which are more costly than others and consequently push up the end price. The quality of a cut depends on human decision and the diamond cutter’s skills taken in this process. Cut grades are defined in laboratory reports by using the GIA standards of Excellent, Very Good, Good, Fair and Poor. A well-cut diamond directs more light through the crown of the diamond. Cutting determines Brilliance which is how both external and internal white light is reflected from the diamond; Dispersion, sometimes known as Fire, results from separate light rays which cause colour flashes to move through the stone; and Scintillation or Sparkle shows the colours as the diamond is moved in different directions.

The most popular cut is Round, also known as Brilliant, a constantly fashionable cut, whereas some of the other more complicated cuts tend to be trend-related. The Princess cut is either rectangular or square; Cushion cut, also known as Pillow cut, is similar in shape except that the corners are rounded. Other cuts which are more complicated to cut are boat-shaped Marquise, rectangular Emerald, Radiant, Pear, Oval, Asscher and Heart.

Clarity is noted with respect to the kind of inclusions seen, their size, colour and position within the stone. It is as subjective as colour grading, hence the necessity to be assured of certification coming from a trusted source. The grade then reflects the degrees of visibility and this affects the price.

The GIA Diamond Clarity Grade scale has five main categories of clarity characteristics:

Flawless (FL): no internal or external imperfections visible under 10x magnification – very rare constituting about 2% of the world’s diamonds.

Internally Flawless (IF): no internal imperfections visible under 10x magnification but with minor finish faults which can be removed by polishing – also very rare.

Very Slightly Included (VVS1 and VVS2): difficult to see very, very small imperfections under 10x magnification; however, these diamonds are of excellent quality. Less expensive stones are graded as Very Slightly Included (VS1 and VS2), Included or Imperfect (I1, I2 & I3).

Colour is graded on a scale ranging from D (colourless) to Z as the colour increases. Grades G to J are in the range of ‘near colourless’ and a possible yellow tinge will only be seen under high magnification. More intense colours than a Z grading are known as Fancy colours, some of which are rare and command high prices. Examples of these are bright yellow, champagne, pink, blue and green. Orange, purple and red diamonds are very rare as the more intense the colour, the rarer and more valuable is the diamond. 

A 5th C is Care – this is imperative especially for valuable diamonds. If they are used in jewellery, then have them cleaned and checked professionally once or twice a year. Store separately from other jewellery items and enjoy every moment of wearing them.

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