The difference between CARAT and KARAT?
CARAT - as weight
The carat, spelled with a "c," is a unit of mass used for weighing gems. It is equal to 200 milligrams. The word carat is derived from the Greek word keration, meaning "fruit of the carob," and went through Arabic and Italian permutations before it reached its final spelling. Because of their uniform size, carob seeds were used as weights on precision scales. Long ago, many different countries had their own carat weight unit, which was roughly equivalent to a carob seed.
At one point the carat was roughly the weight of the grain in the Troy pound system of measurement, under which the standard was close to 205 milligrams. Countries employing the metric system used this measurement despite its limited range. Finally, in 1907, the metric carat of 200 milligrams was established, and is universally used today.
The carat can be divided into points. There are 100 points to a carat, therefore a half-carat stone (0.50ct) can be called a "fifty pointer," a tenth of a carat stone (0.10ct) can be called a "ten pointer," and so on. Even tiny stones weighing less than a point (<0.01ct) are commonly used in intricate pave work. A stone called a "half pointer" (0.005ct) or a "quarter pointer" (0.0025ct), if fully cut with 58 facets and in a good color, can add a lot of flash to a piece of pave jewelry.
Further, when dealing with strictly diamonds, a paragon is a diamond weighing 100 carats or more, and is therefore 20,000 milligrams or 20 grams. In other words, a paragon is a big sucker.
KARAT - as purity
The karat, spelled with a "k," is a measure of the purity of gold and platinum alloys. If you have 24-karat gold, you have very nearly pure gold, about 99.99% pure. If you have 12-karat gold, it is only 50% pure, and so on. Therefore, if you have 1-karat gold, you have material that is one twenty-fourth (1/24) purity by weight.
In the US and Canada, the karat system is the established measurement of purity. Internationally, however, the karat system is complemented (and in some cases superseded) by the millesimal fineness system. This system measures the purity of precious metals by parts per thousand of pure metal in the alloy.
For example, 24-karat gold has a millesimal fineness of 999 and 14-karat gold has a millesimal fineness of 585. Whereas in the past you might find a stamp inside the shank of a ring that said "18K," you are more likely now to see the numbers "750" instead.
The Grading Of Diamonds
4c’s
Finding what is important when purchasing a DIAMOND
Carat — .25, .50, .75, 1.00, ---- 4.00ct
Clarity —
F / Flawless: No internal or external flaws. Extremely rare.
IF / Internally Flawless: no internal flaws, but some surface flaws. Very rare.
VVS1-VVS2 / Very Very Slightly Included (two grades). Minute inclusions very difficult to detect under 10x magnification by a trained gemologist.
VS1-VS2 / Very Slightly Included (two grades). Minute inclusions seen only with difficulty under 10x magnification.
SI1-SI2 / Slightly Included (two grades). Minute inclusions more easily detected under 10x magnification.
I1-I2-I3 / Included (three grades). Inclusions visible under 10x magnification AS WELL AS to the human eye. We do not recommend buying diamonds in any of these grades.
Color —
To grade 'whiteness' or colorlessness, most jewelers refer to GIA's professional color scale that begins with the highest rating of D for colorless, and travels down the alphabet to grade stones with traces of very faint or light yellowish or brownish color. The color scale continues all the way to Z.
Which Color Grade Should I Choose? Diamonds graded D through F are naturally the most valuable and desirable because of their rarity. Such diamonds are a treat for the eyes of anyone. But you can still obtain very attractive diamonds that are graded slightly less than colorless. And diamonds graded G through I show virtually no color that is visible to the untrained eye.
Cut —
Diamond cut is perhaps the most important of the four Cs, so it is important to understand how this quality affects the properties and values of a diamond. A good cut gives a diamond its brilliance, which is that brightness that seems to come from the very heart of a diamond. The angles and finish of any diamond are what determine its ability to handle light, which leads to brilliance.
As shown in the images below, when a diamond is well-cut, light enters through the table and travels to the pavilion where it reflects from one side to the other before reflecting back out of the diamond through the table and to the observer's eye. This light is the brilliance we mentioned, and it's this flashing, fiery effect that makes diamonds so mesmerizing. In a poorly cut diamond, the light that enters through the table reaches the facets and then 'leaks' out from the sides or bottom of the diamond rather than reflecting back to the eye. Less light reflected back to the eye means less brilliance.
