Here is some important information on how to grade a diamond you are thinking about buying.
Many, if not most, people have heard about the four C's of diamonds through advertisements or direct contact with jewelry salespersons.
However, while familiar with the concept, most individuals are a little sketchy on the facts when asked to explain what these concepts mean.
The four C's, as promoted by the jewelry industry, can be broken down into four relatively easy to remember parts termed:
1) Carat Weight
To grade a diamond, the first aspect, weight, is pretty black and white. Diamonds are weighed in carats, composed of 100 points. Basically, a half (1/2) carat stone is .50 carats or 50 points. To simplify matters, the term carat may be abbreviated as "ct." Special diamond scales calibrated to a thousandth of a carat are generally used in the jewelry trade. Occasionally you may hear the term "four grainer" referring to a 1 carat stone. Each grain is equal to .25 ct or 25 points. If you think in terms of grams, 1 gram is equal to 5 carats. This metric equivalency provides a level of uniformity anywhere in the world. Due to the limited supply of larger diamonds, the value of the stone rises proportionally as the weight of the stone increases. For example, four .25ct diamonds of the same quality will not equal the value of a single 1ct stone of identical quality. The disparity becomes more noticeable as the size and quality of the diamond increases.
Weight not Size.
Carat describes the actual weight of a stone, not the size. Due to the differences in density, some stones weigh more than others. Therefore, two different stones may both be 1 carat but have different sizes.
When you grade a diamond, Clarity is determined by the location, type and extent of inclusions or blemishes present in or on any stone. Inclusions occur within the stone, while blemishes are external in nature. There are many grading scales used to describe clarity, however, that used by the GIA (Gemological Institute of America) is probably the most well known. The scale can be broken down as follows:
Flawless (no inclusions under 10x loupe) IF (internally flawless - blemishes exist) VVS (very, very slightly included 1 or 2 - minute inclusions) VS (very slightly included 1 or 2 - minor inclusions) SI (slightly included 1 or 2 - noticeable inclusions) I (imperfect 1, 2 or 3 - observable inclusions)
Grading is always performed with a 10 power loupe or microscope under proper lighting by a trained observer. Inclusions in stones graded I1, I2 and I3 can be seen by the unaided eye. In many cases the term "imperfect" will be substituted for "included" when describing VVS, VS and SI stones. Generally, diamonds in the I1-I3 ranged are referred to as imperfect 1, 2 or 3.
Clarity makes a significant impact on the price of the stone. When shopping for diamonds, you should remember that “clarity” does not affect diamond brilliance. The better the clarity does not assure a more brilliant stone. Actually, the stone cutting determines the brilliance of a stone. In fact, most people cannot discern the visible difference between the grades “Flawless” through “Slightly Included.”
When you grade a diamond on color, you use the GIA scale which ranges from D to Z, with D being colorless and Z being heavily (usually yellow) colored. Colorless stones (designated D, E, and F) command the highest prices. Diamond colors run somewhat in groups:
Colorless D E F
* The tint viewed may be yellowish, brownish or even gray.
To grade diamond, a non-reflective white background is used. Graders have to be careful about surrounding environment. Clothing color, lighting and color of the instruments used may affect the outcome.
There are certain diamonds that are called fancies. These stones have intense natural colors that in some cases are very rare and command exceptional values. These stones are not color graded with the scale above. Brown and yellow diamonds are the most common members of the fancy group, and have a distinct beauty of their own. Reds, blues and greens are extremely rare and highly sought after by designers and collectors.
The breathtaking beauty of a diamond comes from a combination of fire (flash of rainbow colors from within) and brilliance (the burst of sparkling light). This dazzling beauty is a direct result of the cut. When you grade a diamond, the last of the four C's, cut, is a little more complicated than just the shape or visible form of the diamond. Cut also refers to the style of faceting as well as the symmetry, proportion and finish (known in the trade as the "make"). There are three basic styles of faceting: brilliant cut, step cut and mixed cut. Designed for maximum sparkle, the brilliant cut uses many triangular and kite-shaped facets. Instead of sparkle, a step cut focuses on elegance by using fewer facets and more trapezoids and rectangles. A mixed cut combines the step and brilliant cut styles for a unique beauty.
All diamonds are cut to certain tolerances designed to maximize the play of light within the stone. If the stone varies too greatly from the accepted standards, light is lost through bottom or sides reducing the liveliness and overall beauty of the stone. As a general note, most full cut round brilliants have either 57 or 58 facets, depending on the absence or presence of a culet (the bottommost facet on a stone).
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