The GIA (Gemological Institute of America) has developed a precise color-scale to
determine the exact color of a diamond. The more colorless a diamond is
(so not with a yellowish or brownish tinge), the rarer and as a result more valuable it becomes. This scale is sorted in alphabetical order. D is the whitest, or better most colorless, followed
by E, F and so on up to the color Z.
As well regarding the clarity of a diamond, the GIA (Gemological Institute of America)
has a precise scale underlying explicit regulations. If a gemologist does not detect
(10x magnification under the microscope) any inclusion or blemish, nor inside the diamond or on its surface, such a diamond may be designated as Flawless (FL – loupe clean, impeccable), and
is without a doubt an absolutely clean and perfect diamond. In case, that such a gemstone does not show any inclusions (internally) but maybe some slight imperfections on the surface (which
mostly refers to the polish and is stated in the certificate "minor details of polish are not shown"), it is designated as an IF (Internally Flawless- loupe clean/inside). The next clarity level,
VVS (Very Very Slighlty Included) refers to diamonds, showing under the microscope (10x magnification) inclusions which are even for a gemologist very very difficult to detect. Depending on
the location of these inclusions (surface area or maybe at the side or bottom) one differentiates between VVS1 (superior clarity) and VVS2. The following clarity level is VS (Very Slightly
Included). A diamond gets this grading if the gemologist detects at 10x magnification very small inclusions, and again, to be precise regarding the location of these inclusions, VS (Very Slightly
Included) is divided in VS1 (superior clarity) and VS2, similar to the previously described VVS-clarity. When it comes to the grading SI (Slightly Included), the expert clearly identifies
inclusions at 10x magnification, and again this clarity-level is divided in 2 quality gradings. Here again the same rules apply, depending on the location of these inclusions and the gemologist
differentiates between SI1 and SI2. From this clarity-level the brilliance is visibly affected in comparison to a VS or VVS graded diamond – even for the human eye.
The lowest grading in the GIA-clarity-scale is I (Included , divided in I1,I2 and I3), or better known under the designation Piqué. Here are inclusions clearly visible with the naked eye and
both, brilliance and colour of the diamond are negatively affected.
Source : Gemological Institute of America (GIA)
A diamonds weight is measured in Carat, which may not be confused with the designation Karat of gold. One Carat is equivalent to 0.2 grams – experts divide one Carat into 100 points. A
"Half-Carater" (0.50ct) weighs according to that 0.1 grams, and is amongst experts specified as a so called "50-pointer“. Although Carat is a unit of weight, perfect cut Round Brilliants
allow a certain conclusion regarding their size (diameter) in connection with their Carat Weight. The "Rapaport Diamond
Specifications" require for certain Carat-Weights a minimum diameter in millimeters, but this applies explicitely for a "Round Brilliant". Therefore a "Round Brilliant"
of 1 Carat needs to have a minimum diameter of 6.4mm, if this gemstone wants to rank among the highest levels A1 and A2. As the "Rapaport Diamond Report" states the price of a diamond per
Carat, this additional requirement regarding the diameter has been established to guarantee, that a final customer does not only pay for a Carat,
but receives a "Round Brilliant" which corresponds to the highest standards and shows its "Carat Weight" how it should.
But again, this guideline does only apply to the "Round Brilliant" and not other shapes such as Emerald-Cut, Heart-Shape etc..
Furthermore a very important criteria with a Round Brilliant is the Cut. During the last centuries there were various types of cutting; however the Round Brilliant as we know him today, ranks
among the most famous and popular. The name "Brilliant“ originates from the french word "brillant“ which means bright or shiny. Tolkowski, the Belgian mathematician, created in 1919 the classic
Brilliant-Cut with 57 facets, which resulted in a maximum of brilliance – until today the benchmark. A Round Brilliant is
allowed to have 58 facets if there might be one at the Culet of the diamond, but this 58th facet may not be more than very small, if the cut shall be graded "excellent".
But the GIA (Gemological Institute of America) does not only grade the Cut but in
addition also the Polish and the Symmetry. As usual the grading scale starts with the best: Excellent, which is followed by Very Good, Good, Fair and finally Poor. To receive a maximum
brilliance, perfect lustre and beautiful sparkle a diamond has to be cut in
accordance with certain measurements and proportions. The diamond cutter has to respect always two important things :
A perfect final result and a minimum of loss whilst cutting.
Source : Gemological Institute of America (GIA)
KEY TO SYMBOL
If a diamond is not "loupe clean" but has inclusions or certain blemishes, each GIA -
Certificate contains an additional category, titled "Key To Symbols". This section shows the nature of the flaws and where they are situated in a particular diamond. There are
characteristics/inclusions which may be considered as "allowed", and do not affect the value in a negative way, as well as those which are undesirable.
Allowed and therefore neutral are the following :
a very fine and small crystalline inclusion comparable to a small dot
a small group of Pinpoints forming a cloud
is a mineral,crystalline inclusion inside the diamond
describes a « feathery », slightly curved interruption of the mineral structure
is a fine elongated crystalline inclusion similar to a fine rod
a group of PINPOINTS, CLOUDS or CRYSTALS forming small ramifications
Undesirable and in some instances reducing the value, or rather not permitted by the « Rapaport Specifications » are the following inclusions/defects :
a missing piece/opening, created when a part of a FEATHER breaks away or if a surface reaching CRYSTAL breaks out during the cutting or polishing of a diamond
a particle of the rough diamond remaining under the surface of the polished diamond
a white or transparent crystal which extends to the surface of the polished diamond
a damage (external influences), mostly at a diamonds girdle
the diamonds girdle is not polished but slightly satinated and feel a little bit like very fine sandpaper
the diamonds girdle shows smallest FEATHERS ; those extend to the surface of the gemstone; mostly a result of the cutting
a small impact area showing smallest FEATHERS
an artificial procedure to improve the CLARITY of a diamond using a laser
Basically, on each GIA-Certificate, internal flaws are marked in red, green or black characterizes external flaws.
Simply can be said, and this applies to all diamonds : The higher the quality standard, the less compromises are allowed, and also the "Key To Symbols"
deserve highest attention when selecting such a gemstone.