Moving down the alphabet towards Z each letter denotes the presence of an increasing amount of yellow or brown. The grades X, Y and, Z describe diamonds that are yellowish or brownish, however without reaching the intensity to be graded as "fancy".

CUT
Through cutting, the magnificent optical beauty of a rough diamond is revealed. The ideal diamond cut has the optimal proportions, perfect polish and symmetry.
There are specific tolerances for the angles of facets, percentages for the depth of the gem in relation to its diameter, the percentage of the table, or top facet, the alignment of facets, the girdle thickness etc. to produce the maximum lustre, brilliance and dispersion with a minimum loss of weight. If cut is not perfect, even if the diamond has the best colour and most clarity, it will not be beautiful and the price will reduce considerably.
When the term "cut" is used some customers think of shape but there is a difference. Diamonds are cut in different shapes, for example round brilliant, which is the most popular shape, but also in pear-, oval-, heart-shape ,emerald, princess and radiant cuts among others.


CLARITY
Another factor in grading is clarity. It refers to the presence or absence of inclusions or flaws in or on the gem. This could be a tiny crystal inside, growth patterns or blemishes on the diamonds surface.
The rarest classifications on the clarity grading scale are "Flawless" ( FL) and "Internally Flawless" ( IF),
Followed by "Very, very slightly included to the first or second degree" (VVS1 and VVS2), "Very slightly included" (VS1 and VS2), "Slightly included" ( S1 and S2) and finally "Included to the first, second or third degree" ( I1 , I2 , I3 ).
Apart from natural occurring inclusions a diamond's clarity can be enhanced through several methods. Dark inclusions deep inside the gem can be removed by laser drilling. Such diamonds are called "clarity enhanced" diamonds. This treatment is not always permanent and must be disclosed to the buyer.