Every major diamond should be properly graded for the 4-C's' . . .

Cut, Color, Clarity then Carat Weight

The order of value is unfortunately never totally agreed on by those that grade a diamond (including the Gemological Institute of America and its own trade laboratory the Gem Trade Laboratory). However, it is the opinion of Mackley & Company the order should be as presented for determining the maximum value.

We will proceed to give nomenclatures for the cut, color, clarity of a colored stone followed by a definition of carat weight. Any credit for the following should primarily go to the GIA for the developing of ones' thought process in nomenclature. Imagine a grader using one set of criteria and another a completely different standard. (This actually goes on today). This is not to say that all of the following was developed by the GIA, but it is to say the thought process for the grading of a colored stone is accepted as the standard and probably came prior to the GIA's introduction of their standard. Mackley & Company refers to the following as a subjective scientific or educational conjecture method.

Cut: 
1.) In gems, a fashioned gem, as opposed to a rough or uncut gem. 2.) The shaping and polishing of a gemstone. 3.) The proportions to which a gem is fashioned. One of the “four C’s” in gemstone grading. It is the cut that enables a gemstone to make the best use of light.

When a diamond is cut to proper portions, light is reflected from one facet to another and then dispersed through the top of the stone.  If the cut of the diamond is too deep, some light escapes through the opposite side of the pavilion.  If the cut is too shallow, light escapes through the pavilion before it can be reflected.  In essence, each shape has its different parameters for cut by the analysis of its proportion, symmetry and finish.  Current GIA classification grades are excellent, very good, good, fair and poor.  AGS grades 0-10 with 0 being the best. The AGS Cut Grading System considers not only the proportions of a diamond, but also the craftsmanship of its overall symmetry and polish. Most importantly, it uses technology to analyze the cut’s impact on diamond’s overall performance. This results in three categories of the AGS Cut Grade — Light Performance, Proportions, and Finish. 
Beginning on January 1, 2006, the GIA Laboratory started updated versions of the GIA Diamond Grading Report and GIA Diamond Dossier®. These new reports will now provide a single, comprehensive cut grade for all standard round brilliant diamonds falling in the GIA D-to-Z color scale and Flawless-to-I3 clarity scale. Diamonds will receive one of five cut grades from Excellent to Poor.

1	2	3	4	5
Excellent	Very Good	Good	Fair	Poor

PROPORTIONS - Outline balance, length to width ratio, profile balance, total depth percentage, crown height and pavilion depth, bulge, table size, brilliance, extinction and windowing.  FINISH - Polish, symmetry, and facet survey.

Color grade:  Body color in most diamonds is composed on a GIA scale from colorless to light hued (yellow, brown, silver-grey, etc.).  Exceptions to this criteria are fancy colors.  The GIA color scale is as follows with the greater degree of rarity toward the left.  Please note the GIA color chart does not apply to fancy color diamonds. Where possible, Mackley & Company will determine color from the use of the SAS2000 spectrophotometer scan and compared against the Certified Diamond Master Set.

Colorless	Near Colorless	Faint Color	Noticeable Color	Distinct Color	Fancy Color
D E F	G H I	J K L M	N O P	Q R S T U V W X Y Z	Z+

Clarity:  In gemstones, the incidence of inclusions and surface blemishes. One of the “four C’s” in gemstone grading.
When examining a gemstone for flaws and/or internal imperfections, the grader must consider the size, number, position, nature and color of the inclusions or blemishes and summarize the finding into a grade. 
The following are GIA clarity grades for diamonds.  Please note:  There is little question that current GIA/GTL reports and GIA education have been revised or changed since the GIA's clarity system first went into use for reports and education several decades ago. A basic summary is also noted.

Fl-IF (FLAWLESS TO INTERNALLY FLAWLESS)	Flawless diamonds show no blemishes or inclusions when examined by a  skilled grader under 10X magnification.  The following do not disqualify a stone from the flawless category:  An extra facet on the pavilion that cannot be seen face-up.  Naturals totally confined to the girdle, which neither thicken the girdle nor distort its outline.  Internal graining that is not reflective, white or colored, and does not significantly affect transparency. Internally flawless diamonds show no inclusions and only insignificant blemishes under 10X.  Normally what separates IF from FL stones are characteristics that can be removed by minor re-polishing (light surface graining is an exception).
VVS1-VVS2 (VERY VERY SLIGHTLY INCLUDED)	VVS (VVS1 AND VVS2) diamonds contain minute inclusions that are difficult for even a skilled grader to locate under 10X. In VVS1, they are extremely difficult to see, visible only from the pavilion, or small and shallow enough to be removed by minor re-polishing.  In VVS2, they are very difficult to see.  under the loop, nothing seen
VS1-VS2 (VERY SLIGHTLY INCLUDED)	VS (VS1 AND VS2) stones contain minor inclusions ranging from difficult (VS1) to somewhat easy (VS2) for a trained grader to see under 10X.  Small included crystals, small feathers, and distinct clouds are typical. difficult to find under the loop
SI1-SI2 (SLIGHTLY INCLUDED)	SLIGHTLY INCLUDED (SI1 AND SI2) -- SI stones contain noticeable inclusions that are easy (SI1) or very easy (SI2) to see under 10X.  In some SI diamonds, the inclusions can be seen with the unaided eye.  can find easily under the loop
I1-I3 (IMPERFECT)	IMPERFECT (I1, I2, AND I3) -- Imperfect diamonds contain inclusions that are obvious to a trained grader under 10X magnification, can often be easily seen face-up with the unaided eye are so numerous they affect transparency and brilliance or seriously affect the stone's  potential durability. prominent under the loop or no loop needed

Carat:  A unit of weight in gemstones, equal to one-fifth of a gram. Carat weight is one of the “four C’s” in gemstone grading A carat is divided into 100 parts, or decimal fractions, commonly referred to as “points.” The word carat comes from the seed of the carob tree (Biblical locust) and was used in ancient times as a unit of weight for pearls and gems.

The other two characteristics of Buying Gemstones are Cost (everyone has a budget) and Confidence (you are not going to purchase unless you feel good about it, are you?).