The 4 C's
Cut
Of the 4 C's, cut is the most important. Proper cutting of the rough diamond ensures that the ideal proportions are achieved. The accurate placement of each surface facet is essential to its beauty and value. The slightest error can create a substantial difference in the stone's brilliance. A diamond is nothing more than a prism that "refracts" or bends light rays. Correct proportioning is the key to unlocking a diamond's inner beauty.
If cut correctly, light enters through the top or "table" of the diamond and passes through to the lower portion called the pavilion until it strikes the pavilion facets. Here it is reflected back out through the top of the stone or it refracts from facet to facet and then it comes back through the top. It is this refraction of light and the unleashing of the spectrum that give a diamond its dispersion or fire. A diamond which is cut too deep allows light to pass through the sides of the lower part of the diamond. A diamond which is cut too shallow allows light to pass through the bottom of the pavilion.
Clarity
| FL | Flawless, no inclusions or blemishes of any sort under 10x |
| IF | Internally flawless, no inclusions and only insignificant blemishes under10x. |
| VVS1 - VVS2 | Inclusions are difficult to locate or see under 10x. |
| VS1 - VS2 | Inclusions present less difficulty to locate or see under 10x. |
| SI1 - SI2 | Inclusions are readily seen at 10x, although they remain invisible to the unaided eye when the diamond is viewed face up. |
| I1 | One or more inclusions or their effect, can be seen by the unaided eye. |
| I2 | Inclusions are easily visible to the unaided eye. |
| I3 | Inclusions are so obvious and large that they affect both brilliancy and beauty of the diamond. |
FLAWLESS (FL)
A flawless diamond shows no inclusions or blemishes of any sort when observed by a skilled grader under lOx magnification. To establish a stone as flawless, (the Gemelogical Institute of America) GIA Gem Trade Laboratory graders examine it with both a microscope and a loupe.The following conditions will still qualify as stone as flawless:
- Extra facets on the pavilion which cannot be seen when the stone is viewed face-up.
- Small naturals confined to the width of the girdle (unless the girdle is thick).
- Internal graining which is neither reflective, whitish, colored, nor significantly affecting transparency.
How much naturals should influence the clarity grade of a diamond is a matter of opinion. Opinions range from those who think that any natural excludes a stone from flawless or even internally flawless to those who accept naturals of almost any size in the flawless classification.
GIA takes a "middle-of-the-road" position: If a natural is small enough to be confined within the width of the girdle (except when the girdle is thick) and does not affect the symmetry of the stone by creating a flat spot or indentation, it is considered an identintifying characteristic and does not influence the clarity grade. If, on the other hand, the natural flattens or indents the girdle outline, or can be seen when the stone is viewed face-up, it does affect the grade.
INTERNALLY FLAWLESS (IF)
This grade applies to diamonds which have no inclusions, but do have some minor surface blemishes. Characteristics such as surface grain lines, naturals, and extra facets on the crown, render a diamond internally flawless rather than flawless. Diamonds classified as internally flawless must be free from any internal imperfection when examined by a skilled diamond grader using lOx magnification. Blemishes that can be removed by minor repolishing separate the internally flawless from the flawless grade. The one exception is a diamond that reveals minor surface grain lines which ordinarily can not be removed by repolishing.
VERY VERY SLIGHTLY INCLUDED (VVS1, and VVS2)
These grades describe diamonds which contain minute inclusions that are difficult even for skilled graders to see under lOx magnification. An example of VVSI might be a minute pinpoint or hairline feather or perhaps a pinpoint or two visible under the bezel facet. To keep the VVS grades in perspective, it should be noted that they represent the top clarity grade carried by most suppliers and retail jewelers. The VVS grades have often been and still are, presented as flawless or perfect diamonds with no intent to misrepresent-by wholesalers and retailers simply because such minute inclusions are difficult to see.Reflective internal graining, bearded girdles,minor bruises,tiny cavities, etc., would be sufficient to grade the stones as VVS1 or VVS2, depending upon degree.
VERY SLIGHTLY INCLUDED(VS1, and VS2)
Although inclusions are clearly visible under lOx magnification in the VS grades, they are characterized as minor or small in appearance. Diamonds in tcolorhese grades might have characteristics such as small included crystals, small clouds, small feathers, or several pinpoints. The inclusions in these grades do not affect the beauty or the durability of the stone.
SLIGHTLY INCLUDED(SI1, and SI2)
These grades describe stones in which the inclusions are noticeable or fairly easy to see under lOx magnification. Typical characteristics include clouds, included crystals, knots, chips, pits, cavities, and feathers. Usually none are visible when the stones are viewed with the unaided eye.
IMPERFECT (I1, I2, and I3)
These grades include diamonds with inclusions which are obvious under 1Ox magnification or can be seen with the unaided eye, and those that have inclusions, such as large cleavages, large included crystals surrounded by feathers, that seriously influence durability. These grades also include diamonds in which the inclusions are so numerous that they affect transparency and brilliance.
The differences between I1, I2, and I3 diamonds are matters of degree. Actually, there are a lot of I1 and I2s sold in the jewelry markets. Most promotional goods, for example, fall into these categories. While you will find them easy to recognize, you will often have to point out to your customers the characteristics that lead to the I classification, and many consumers are happy with them. (As is the case with any diamond, they look their best when they are spotlessly clean. A little time spent explaining this to a customer will help keep them satisfied with what they have bought.).I3, the bottom category, includes diamonds that lack transparency and those with large cleavages and dark inclusions easily visible to the unaided eye.They are actually borderline industrial stones; whether they are graded as industrial or gem qualfty depends onmarket demand.
A large stone with an eye-visible inclusion at or near the girdle may not warrant an I grade, because the inclusion could be removed with much less loss of value than an I grade would suggest. When appraising, some diamond experts grade such stones as I's, but value them on the basis of the recut grade and lower weight they would have if the inclusion were removed
Color
Grades in the color of diamonds range from D-Z, D being truly colorless and of the highest quality. E and F are also graded as colorless while G, H, I and J are near colorless. Diamonds graded K, L, and M will have obvious hints of color and as the scale approaches P you may find subtle changes in hue and tone. The exceptions to the rule are "Fancy" diamonds- in well-highlighted colors that include pink, blue, red, green, and canary yellow. These are particularly rare and highly treasured. To appreciate the quality of a colorless diamond, compare several stones side by side with a jeweler.
Diamond Color
Carat
History of the Carat
Weighing commodities as small and precious as gems demands a very small, uniform unit of weight. To meet this need, early gem traders turned to plant seeds that were reasonably uniform in size and weight. Two of the oldest were wheat grains and carob seeds. Both were common in the gem-producing and trading areas of the ancient world. Wheat was a dietary staple, and indidual wheat grains provided a plentiful and relatively uniform weight standard. Our modern pearl grain, troy grain, and avoirdupois and apothecaries' grains all derived from the wheat grain. (Diamond weights are sometimes approximated in grains).
The carob, or locust tree, produces edible seed pods that are still important as feed for livestock and as a flavoring. Traders used the inedible seeds as a standard weight from which our modern metric carat evolved.
Carat weight was standardized in the early twentieth century. If you had purchased a 'one-carat' diamond in 1895, it might have weighed anywhere from 0.95 to 1.07 metric carats, depending on where you bought it. But between 1908 and 1930, the standard metric carat was adopted throughout most of Europe and in Japan, Mexico, South Africa, Thailand, the USA, and the USSR.
Consumers sometimes confuse the terms carat and karat. Although in some countries the two are synonymous, in the US, karat refers to the fineness of gold alloys (pure gold is 24 karat; 14 karat is 14 parts gold and 10 parts other metal or metals) and carat refers to gem weights.
Carat Weight
When you tell people one diamond weighs more than another, they usually understand what you mean-but few consumers realize how precisely diamonds are weighed. Like most gems, diamonds are weighed in metric carats; one carat equals 0.2 gram-a little more than 0.007 (seven thousandths) ounce avoirdupois.In other words, it takes almost 142 carats to equal 1 ounce. But even this is not precise enough for something so precious. Even with relatively inexpensive diamonds, fractions of a carat can represent hundreds of dollars (thousands, with top-quality stones). For this reason, in the diamond industry, weight is measured to a thousandth of a carat and rounded to the nearest hundredth (or point). Carat Weight Chart
Carat Weight ChartTo visualize how precise this is, consider that a point-a hundredth of a carat-is less than one fourteen-thousandth of an ounce. The term point can confuse consumers, who may think you are referring to the number of facets on the stone, or to the decimal point specifying hundredths.
Rules and Industry Practice
The FTC's Trade Practice Rules for the jewelry Industry (1957) state:
RULE 32: Misrepresentation of Weight, "Total Weight" (a) It is an unfair trade practice to misrepresent the weight of any diamond or to deceive purchasers or prospective purchasers as to the weight of any diamond (Note: The standard unit for designation of the weight of a diamond is the carat, which is equivalent to two hundred miligrams (1/5 gram). While advertisements may state the range of weights of a group of products, all weight representations regarding individual products shall be subject to a 1/200th of a carat (one-half "point") tolerance.)
(b) It is an unfair trade practice to state or otherwise represent the weight of all diamonds contained in a ring or other article of jewelry unless such weight figure is accompanied with equal conspicuity by the words "total weight," or words of similar import, so as to indicate clearly that the weight shown is that of all stones in the article and not that of the center or largest stone. Apparently, this guideline was inadvertently omitted from the FTC Guides for the jewelry Industry (1979). It will probably be reinstated in future revisions. The rule regarding representation of total weight is fairly plain: If you are showing a piece of jewelry set with more than one gem, be sure you are clear in your description of the weights of individual stones.
The "half-point" tolerance means that, in the US, weight must legally be measured to a thousandth of a carat (0.001) and rounded to the nearest hundredth (0.01). It also means that a diamond weighing 0.995 carat can legally be described and sold as a one-carat diamond in the United States.
In many major diamond-trading countries and international industry organizations, a diamond's weight can only be rounded up to the next higher hundredth from nine thousandths of a carat. Following this convention, a stone which weighs 1.768 carats would be rounded to 1.76 carats; but one which weighs 1.769 carats would be rounded to 1.77 carats. Since many of the Quality Analysis Reports prepared by GIA!s Gem Trade Laboratories are used internationally, the labs follow international practice.