Bespoke Craftsman Jeweller and Diamond Dealer Based in Bawtry, South Yorkshire
In white or colourless diamonds, colour is universally graded using an alphabetical scale from D to z with D being the highest grade.
Before the GIA colour grading system was universally accepted, various other systems were used including letters of the alphabet starting at A,B and C with multiple A’s used to grade the best stones, number systems and Roman numerals and the result of all of these grading systems was confusion and inaccuracy and so, to make a fresh start and to avoid any association with previous systems it was decided to us D as the highest grade.
The grader will assess the colour of the diamond using a master set of diamonds of each colour grade. Without comparing diamonds side by side it is very difficult to see the difference between a D colour and a G colour stone.
Stones graded D,E,F are described as colourless, G,H,I ,J are near colourless, K,L,M are faint.
Diamonds and other gemstones are weighed in metric carats. One carat is 0.2 grams and a carat is split further into 100 points (a diamond weighing 50 points is a half carat diamond).
Any diamond weighing more than 1 carat is described in carats and decimals. For example a diamond weighing 1.72 carats would be expressed as one point seven two carats.
The quality of the cut of a diamond is important, because it dictates a diamond’s fire, sparkle and brilliance. A standard round brilliant cut will have 57 facets and how these facets relate to each other will determine how the light will pass through the diamond. The scale for the quality of the cut goes through Excellent, being the highest grade, Very good, Good, Fair or Poor.
As with colour, unless you have stones side by side of differing cut grades, it would be very difficult to tell an Excellent from a Very good cut.
Diamonds are formed under extreme heat and pressure deep inside the earth and often display internal inclusions or external blemishes.
The clarity of a diamond refers to the absence of these inclusions and blemishes. The scale for grading clarity usually contains 11 grades starting with FL (flawless) and IF (internally flawless) followed by VVS1, and VVS2 (very, very slightly included), VS1 and VS2 (very slightly included), SI1 and SI2 (slightly included) and I1, I2 and I3, these are stones with quite noticeable inclusions often able to be seen with the naked eye.
We sell certified diamonds graded from 5 different laboratories.
GIA (Gemological Institute of America)
IGI (International Gemological Institute)
HRD (Hoge Raad Voor Diamant)
EGL (European Gemological Laboratory)
IIDGR (International Institute of Diamond Grading and Research)
GIA developed the 4C’s system of diamond grading in the 1940’s and as such is the most respected certificate worldwide. Their system is now accepted as the industry standard and is used by all grading labs, therefore I would recommend to buy your stone with a GIA certificate. That is not to say that certificates issued by other labs are less worthy, consistency in the grading of the different 4C’s is the key.