My name is Alessandro Greco and I'm Polished diamond certified at I.G.I. Antwerp (International Gemological Institute).
I'm new in e-bay, but hope to satisfy You analizing also very little stones, to give you all the information you need to know how to buy
the most beautyful and precious stones in the world!
Before you start looking for a diamond, you want to have all of the necessary information that is available to you, because the more you know, the better prepared you are to make decisions regarding your purchase.

"LEARN ABOUT THE FOUR C's: CUT, COLOR, CLARITY, CARAT.

CUT
Most diamonds are cut round with a full 58 facets, and a good cut, or make, has more scintillation, more sparkle. It is the work of a master cutter that allows the diamond to be cut in such a way as to permit the maximum amount of light to be reflected through the diamond, and that's a great reflection on you. It is the cut that enables a diamond to make the best use of light.

COLOR GRADING
The most common diamond color is yellow. Most diamonds have a slight hint of yellow and the diamond color scale is based on the amount of yellow present in a diamond. Diamond color is graded according to the GIA Grading Scale. Grades are based on the amount of yellow that is visible when viewed facedown through the pavilion on a white diamond color card using daylight equivalent fluorescent light. Each color grade is based on a very small range. When a diamond is color graded it is compared using a set of master stones. Master stones are a set of real diamonds that display a range of known colors. It is extremely difficult to see the color differences within diamonds, but master stones help graders distinguish between one color and the next.
GIA color-grading scale
As you can see the color-grading scale ranges from D to Z. The highest color grade and whitest stone available is a D color diamond. This is also the rarest color grade, which translates to a higher value. Colors E and F have no detectable color to the naked eye and they fall into the Colorless category. Diamonds in the G to J color range have a hint of body color and are considered Near Colorless. The eye begins to detect faint traces of yellow in diamonds that are in the J to M range. Diamond Ideals typically sells diamonds in the color range of D to J and occasionally K.
The AGSL uses a slightly different color grading scale. The AGSL ranks the stones from 0-10, in 0.5 increments with 0 representing the equivalent of colorless D stones, and 10 representing the equivalent of X, Y and Z colored diamonds.
Ideal Cut Diamonds Can Mask Subtle Color Differences:
 Ideal Cut diamonds offer a little flexibility in color selection. Because Ideal Cut diamonds are designed to maximize brilliance and scintillation they also tend to mask subtle color differences making H and I color diamonds appear beautifully white. Ideal Cut H and I color diamonds tend to appear whiter than poorly cut diamonds of the same color.
Color can save you money
A diamond's color grade does not pertain to the "face-up" look of a particular diamond, but rather to the "body" color of the material. The best way to assess diamond color is to view it from the side, un-mounted, against a white background, using a daylight fluorescent bulb.
An AGS Triple Ideal Cut Hearts & Arrows diamond reflects more than 99% of the light back through the crown. There is virtually no light leakage in these stones. What this means to you is that rather than seeing the diamond's color, when you look at a Hearts & Arrows diamond, all you see is white light and scintillation. These diamonds appear whiter than non-Ideal diamonds. Keep this in mind if budget is an issue. By dropping one color grade in an AGS Triple Ideal Cut Hearts & Arrows diamond, you will not be giving up anything in the look of your diamond and you will be saving money.
 
CLARITY
The diamond's clarity is a description of its internal purity. With fewer imperfections within the stone, the diamond is more rare and has a higher value. The clarity scale was developed by the Gemological Institute of America (GIA) to quantify these imperfections. The American Gem Society (AGS) uses the same standards as the GIA; however, the AGS uses a numerical system where "0" is the cleanest (GIA "IF") and "10" is the most imperfect (GIA "I3").
All diamonds are systematically graded and plotted under 10X magnification. If a trained grader cannot see a clarity characteristic at 10X, it does not affect the clarity grade.
Five Factors That Determine Clarity:
•Size
•Number
•Position
•Nature
•Color
All of the above factors are taken into consideration when a diamond is assigned a clarity grade.
Clarity Grades Defined by the GIA:
Flawless — Flawless diamonds have no inclusions or blemishes when viewed under 10X magnification by a skilled grader. A diamond can have naturals confined to the width of the girdle, extra facets on the pavilion that are not visible face-up, laser inscriptions confined to the girdle and internal gr