The 4C’s – Carat

Diamond in its original form, before it is polished and shaped is called rough diamond or just rough. About half of the world’s rough diamond comes from central or south Africa. In addition there are significant diamond deposits in Russia, Canada, Brazil, Australia and India. There are approximately 130 million carats of diamonds mined annually.

The carat is the unit of weight that is used to measure and quantify all diamond. All diamonds whether in the rough form before polish or after as a finished gem are sold “per carat”. The carat is one of the four criteria used to describe and value all diamonds. The others of course are color, clarity and cut. The De Beers Corporation created these 4C’s in 1939 as a ways to standardize the description and value of all gem quality diamonds.

Historically, the word “carat’ comes from the Greek “fruit of the carob”. The carob is a seed, which was used as the standard unit of measure on scales for thousands of years. The carob seed was used because of the belief that all carob seeds were uniform in weight. Today however, a carat is defined as the weight of two hundred milligram’s and is divided into one hundred points of 2 milligram’s each. It is for this reason that we say there are one hundred points in one carat of diamond. As such, .50 points would be a half a carat, .25 points a quarter carat, .75 points three quarters of a carat and so on.

In the mining of diamonds there are significantly more smaller rough diamond found than larger rough diamond and so and diamonds are bought and sold throughout the world, smaller diamonds cost less money “per carat” than larger diamonds. This difference in price, which can be substantial in the total cost of a stone, is due in part to the market conditions of supply and demand.

Thus, all diamonds are grouped according to size. Stones between 1 to 4 points have the same “per carat” price given that color, clarity and cut remain the same. The same stones between 5 and 7 points have a different “per carat” price. These price breaks continue, as the diamonds get bigger. Diamonds between 8 and 11 points are priced less than those between 12 and 14 points, diamonds between 14 to 18 points are priced less “pre carat” than those 18 to 22 and so on. These price breaks continue throughout the entire range of diamonds and continue more prominently as diamonds cross the full one-carat size.

These differences in the price per carat of a diamond solely related to its size or carat can have a dramatic effect on its price. If we use a quarter carat, half-carat and three quarter carat diamond as an example, we can illustrate this difference. A quarter carat diamond, H in color and SI1 clarity, a nice white stone with some imperfections in the stone, none of which would be visible to the naked eye could cost about $225.00 dollars. The same quality stone in a half-carat size about $900.00 dollars and a larger stone of .75 points about $1500 .00 dollars.

To further the example, that same stone as a one-carat diamond would be close to $4000.00 dollars but as a .90-carat, (just under a carat) it would cost just $3000.00 dollars. That’s a difference of about $1000.00 dollars for 10 points in size which will not be seen once that diamond is put into a ring. The same differences in prices would hold true regardless of what colors and clarities we chose. The only variable here was the carat weight or size of the diamond.

While decisions about the size and look of a diamond are always very personal and important, a real understanding of each of the 4C’s, carat, color, clarity and cut can give invaluable information to anyone interested in learning about or purchasing a diamond.

The 4C’s – Color

For more than six thousand years diamonds have had a place in man’s history. They have been sought after as mineral’s possessing mystical properties, as objects of beauty and as symbols of status and power. However, before De Beer’s creation of the 4c’s (color, cut, clarity, and carat), in 1939, there were no universally accepted standards used to categorize and describe the qualities of diamonds.

Color is an attribute of a diamond which is immediately visible to the naked eye and as such can immediately be compared to other diamonds which are seen as “whiter” or not as white. The color of a diamond is determined by its chemical makeup and impurities inside the stone. There are diamonds of many different colors, from white to black, brown, yellow, pink, orange, red, green, purple, blue and grey. While technically the color white is made through a combination of colors, it is easier in a discussion of diamond ‘whiteness” to think of white as the absence of color. As a diamond has less color in its crystals, it is colorless and appears whiter. When we say that a diamond is colorless or “D” in color, we are saying that this is the whitest a diamond can be. As with any color there are slight variations to that color. A diamond color is no exception and so there are varying color grades of white.

In the 1940’s, the Gemological Institute of America began assigning letters to describe the different levels of whiteness found in a diamond. This diamond color grading chart defines diamond color beginning with the letter “D” and continuing through the letter “ Z”. This is considered the normal color range of all diamonds. Diamonds not in this range due to increased or intense color are considered “fancy colored diamonds” and are graded using many of the standards and terminology used to grade colored stones like ruby, emerald and sapphire. Beginning, however, with the letter “D” and continuing with the letters “E, F, G, H, I and sometimes J, are generally considered white stones. The Gemological Institute of America has defined the level of white attributed to diamonds in each of these color grades. As more color is found in the crystal structure of each diamond, it appears less colorless and thus less white. The difference in these color grades of diamonds can only be seen by comparing the color of one diamond with another. Diamonds are generally graded loose, essentially upside down with the culet or point of the stone facing upwards. Yet, it is difficult to determine the “whiteness” of a diamond color in the abstract. Professional’s in the diamond business, grade diamond color by comparing each stone to a master set of color-coded synthetically created crystals.

In addition, diamond color may only be determined before the stone is placed in a piece of jewelry. Diamonds like prisms will reflect the color of the metal placed around it, and so a diamond will always appear whiter when surrounded by a white metal, like platinum or white gold. So much so that it can actually appear to be one full grade higher on a diamond color chart. As an example a G color stone will appear to be F in color in a platinum or white gold ring.

Ultimately, our perception of the whiteness of a diamond is influenced by the amount of light which passes through the diamond, and how that light is broken up or refracted in the stone and then reflected out of the stone. This refraction and then reflection of light in a diamond is what is responsible for the “fire” or sparkle of a diamond. This leads us to a discussion of another of the 4C’s, the “clarity” of a diamond.