Carat is the term derived from the Ancient Greek and Arabic names for the carob seed– Qirrat in Arabic and Keration in Greek. Now-a-days, carat is used to scientifically define the weight of any gemstone, including diamonds. Diamonds are measured, by their weight and not on the basis of their size. That is why you must not get confused when carat is mentioned as it defines the weight and not the size of the diamond.

A metric “carat” is defined as one fifth of a gram, 200 milligrams or 1/5 of a gram. Each carat can be sub divided into 100 points, where one point is equal to 0.01 carat. The heavier the diamond is, the greater the carat weights. Often, jewelers describe carats in ¼ increments.

The size of the diamonds can vary by a great amount, it could be a fraction of a carat or it could also be as large as several carats. Given the rarity of large stones on earth, the price rises rapidly with size; therefore, a single 2-carat diamond will price much more than two 1-carat diamonds. This is the reason why large diamonds are more expensive and also because they possess better color, better texture and are more clear, hence pretty exclusive.

The slider below compares the relative sizes of stones and describes how much a round brilliant diamond of a certain size is likely to weigh. This chart is for educational purposes only and shows a guideline for diameter and carat weights. It is not demonstrative of other cuts or shapes. It is also not valid to colored gemstones which have a unlike density from diamonds.

One of the most important attributes of a diamond Sis its dimensions as it describes its form. In addition to the carat weight, you must always consider the distance across the top of the gem as well. At times, people tend to misunderstand that half a carat is half the size of one carat. Rather, half a carat is equal to half the weight of one carat diamond; however, the millimeter difference on a round stone is only 1.35mm.

The average measurement for a 0.50ct stone is 5.00mm, while the average 1.00ct stone measures approximately 6.35mm. Although, carat weight might specify a diamond’s size, the shape and cut of a stone also plays a role on appearance of how large or small the stone seems. For instance, a shal-low diamond can sometimes appear larger compared to a deep one purely because of the way it is shaped. Similarly, a diamond´s cut can have effect. Such as elongated shapes aims to maximize carat weight, letting them look larger than round stones of the same weight as illustrated in the chart below.

The definition of cut does not stand for “shape” as this term defines how well a diamond has been made from its rough form, to look glossy and brilliant rather than what figure it has been fashioned into. In other words, the type of cut illustrates the process applied by the diamond’s last polished finish. Thus, cut plays a big role in determining the price of a stone. For instance, the most known cut for a diamond is the round brilliant cut; however, there are also Swiss cuts, or round old European cuts, and round 144-facet cuts.

Furthermore, the diamond’s cut is ranked by a certification body; the GIA (Gemological Institute of America) grades on the basis of a five point scale rating from “excellent”, “very good”, “good§, “fair”, to “poor”. Other laboratories as the AGS may use other scales and definitions: “Excellent” or “ideal” for the best diamonds as these grades are approved to diamonds with the top level of sparkle intensity and rich light reflection, while Fair and Poor grades indicates less sparkle and poorer brightness. Below slider illustrates GIA cut grades for a diamond cut

The term clarity is an illustration of a diamond's purity. Clarity is defined by a diamond's, naturally happening, and internal characteristics from rough form. Each diamond has so called “birthmarks”; small imperfections inside, or on surface. These characteristics are sometimes not visible to the naked eye and they are what make each diamond unique. The characteristics, or inclusions, may look like crystals, feathers, clouds or dark spots and the quantity, size, and location of these inclusions does have an effect on a diamond's value. Diamonds with fewer and smaller inclusions generally are more brilliant, assuming that the color and cut are the same.

Diamonds used in jewelry are clean to the naked eye, however, in a certified diamond, the cracks are defined on the certificate and act as fingerprint for categorizing a particular stone.

The continuing is the GIA clarity scale, in correspondence to define clarity grades which is very gen-erally used in world wide.

A large percentage of jewelry is made with SI quality diamonds. These diamonds are good for di-amond studs or multi-stone diamond earrings, rings, bracelets or as accents in gemstone rings. I quality diamonds are acceptable as well for diamond jewelry or as accents but the sparkle is dropped by the number of inclusions and their location.

Color is another significant grading aspect for buying or selling diamonds. Most diamonds have an indication of color and subtle color differences, which are graded based on their overall body color, on a scale developed by the GIA and AGS. At the GIA this scale runs from “D” to “Z”. Following charts below show how the difference between any colors can be very subtle.

In order to achieve the premier degree of accuracy, diamonds have to be color graded loose and with proper equipment. Colorless diamonds are rarest and most valuable of all. Color variations are a consequence of natural forces (i.e. trace elements, pressure, temperature etc.) during the formation of diamonds within the Earth. Therefore, a color grade scale is useful to categorize the shading differences from one diamond to another.