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Diamond Tutorial
Diamond Carat
A carat is a unit of weight for diamonds and other gems. The metric carat of .200 grams, or 200 milligrams was adopted in the United States in 1913 and now standardized in the principle countries of the world.
If other factors are equal, the more a stone weighs, the more valuable it will be. Gemological laboratories measure carat weight when the diamond is loose (unmounted). While it is possible to estimate the weight of a mounted diamond, the lab uses ultrasensitive scales to achieve an exact weight, measured 3 decimal places, although the third decimal place is not usually mentioned at the retail level.
Here are several ways to express 1 carat:
- 1 ct.
- 200 milligrams
- 1/5 gram
- 100 points
- 4 grainer (not often used in retail environment)
One carat (not to be confused with Karat-the measure of purity of gold) is the equivalent of 200 milligrams.
One carat can also be divided into 100 "points." A .75 carat diamond is the same as a 75-points or a 3/4 carat diamond.
The term carat is a derivative of the word carob. Carob seeds, which are surprisingly uniform in weight, were used as a reference for diamond weight in ancient civilizations. One carob seed equaled one carat.
It is often assumed that a 1-carat diamond costs exactly twice the price of a 1/2-carat diamond. This is not the case. Since larger diamonds are found less frequently in nature, a 1-carat diamond will cost much more than twice as much as a 1/2-carat diamond, assuming color, clarity and cut remain constant.
The weight of a diamond is numerically expressed in carats
Diamond weight is subdivided further into smaller units commonly referred to as points. A point(s) is a scale of weight that is equal to .01 carat. A one carat diamond is made up of 100 points. The term point(s) does not refer to the amount of facets or individual flat surfaces a diamond possesses as its definition is sometimes incorrectly interpreted.
A diamond that weighs .50 carat or 50 points would be considered 1/2 carat in size. A diamond that weighs 1.00 carat or 100 points is considered a carat. A two carat diamond would weigh 2.00 carats, 200 points or 400 milligrams.
Diamonds of jewelry quality are still relatively rare. And large diamonds are rarer than small diamonds. The scarcer a diamond is, the greater its worth. So a larger stone doesn't just cost more. It also costs more per carat.
Plus, there are three other factors that contribute to the diamonds price (color, cut and clarity). And although carat weight is important, like the other three Cs, no one of them is automatically more important than the others. They all have to be factored in together in assessing the true value of a diamond.
How Carat weight Affects Value
Larger diamonds are more rare and in more demand than smaller diamonds of the same quality, so they can be sold for a higher price. A one carat diamond solitaire ring is nearly always more expensive than a diamond ring made up of multiple diamonds that are similar, but smaller, even though they total one carat or more. Carat size describes the weight of a diamond. 1 carat is equivalent to 200 milligrams. A carat is then divided into 100 points. Therefore, a 50 point diamond weights 100 milligrams.
Diamonds that weigh just under the next full carat are typically less expensive than diamonds passing the full-carat hurdle.
The same principle applies at the dividing line for 2 and 3 carat diamonds etc.-as the price increases in leaps with each complete and full carat unit. Price jumps for full and numerically "round" "stages" are also applied to diamonds of lesser weights, i.e., a 50 points diamond vs. a 49 points diamond is more valuable weight per weight by being a "full" 1/2 carat (there are 100 'points' in one carat. Thus, e.g., 0.50 or, 1/2 carat is equal to 50 points).
Clarity
The clarity of a diamond refers to how clear, or "clean" the diamond is. The more "clean" the diamond, the higher the price. Most diamonds have "imperfections" in them. The clarity scale is a measure of the severity of those imperfections or "inclusions" as it is known in the trade.
Both of these distinguishable features together are called clarity characteristics. A clarity grade is determined by the relative absence of clarity characteristics.
The following is the GIA Diamond clarity-scale:
(FL) FLAWLESS
Shows no inclusions or blemishes of any sort under 10X magnification when observed by an experienced grader
(IF) INTERNALLY FLAWLESS
Has no inclusions when examined by an experienced grader using 10X magnification, but will have some minor blemishes
(VVS1 and VVS2) VERY VERY SLIGHTLY INCLUDED
Contains minute inclusions that are difficult even for experienced graders to see under 10X magnification.
(VS1 and VS2) VERY SLIGHTLY INCLUDED
Contains minute inclusions such as small crystals, clouds, or feathers when observed with effort under 10X magnification.
(SI1 and SI2) SLIGHTLY INCLUDED
Contains inclusions (clouds, included crystals, knots, cavities, and feathers) that are noticeable to an experienced grader under 10X magnification.
(I1, I2, I3) INCLUDED
Contains inclusions (possibly large feathers or large included crystals) that are obvious under 10X magnification and may affect transparency and brilliance.
The Clarity Enhancement Process:
During the clarity enhancement process we insert a microscopic amount of material into the imperfection. This material has the same optical refraction index as the diamond. When light travels from one medium to another, it either changes its course or reflects in a different direction. When light attempts to pass through a non-enhanced diamond that has a feather, the light hits the feather and reflects in a number of directions. That is why we see the feather, and the diamond doesn't appear to be clean. With a Clarity Enhanced diamond, the light passes through the natural feather because the material used for the enhancement has the same optical characteristics as the diamond. This makes the enhanced imperfections invisible.
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