The 4 C's Explained


Diamonds naturally come in every color of the rainbow but the most common are those with a slight yellowness. The more common diamond colors are ranked on a scale from D (absolutely colorless) to Z (naturally yellow). The rarest and most expensive diamonds are either D-colorless or of a natural fancy intense color such as blue, yellow, pink, or the most rare-red.

However, not all colored diamonds are natural; some are treated with harmless radiation to artificially enhance color. These diamonds are significantly less valuable than natural colored diamonds because they are not as rare. A diamond’s color should be determined when it is “loose” or not in a piece of jewelry yet. This is because the color of the jewelry can play visual tricks on the human eye making a diamond appear more yellow in yellow gold or whiter in platinum.


The most complex factor affecting a diamond’s price. Diamond cutting is still done by human hands. When a diamond cutter cuts a stone, he or she must make difficult decisions about how large it will be, what shape it will become, and how many imperfections will be left in the final product. After these decisions are made, it is the craftsmanship and fine motor skills of the diamond cutter that determines how much the stone will sparkle and how much attention it will draw.

The slightest mistake can ruin a diamond’s symmetry and in doing so dramatically decline the beauty and price of the stone. Even a flawless and colorless stone can become dull when badly cut. Cut Quality When properly cut, a diamond will reflect almost all of the light that enters it through its top. If improperly cut, some to most of the light will exit out of the bottom or side of the stone. A properly cut diamond will have symmetrical facets (the windows and mirrors of the stone), good proportions (not too deep or too shallow), and careful finishing details (like flawless polishing and permanent treatments).

If properly cut, the diamond will return a white shaft of light from its top (called brilliance), sparkle every time that it moves (called scintillation), and send rainbows out of its many facets (called fire or dispersion). These three elements of a diamond’s light mix in unique and fascinating ways and it is solely a matter of preference from person to person as to what the best mixture is.

Another matter of preference is the shape that a diamond is cut into. Any shape other than a classic round is called a "fancy cut." Some of the more common fancy cut shapes are: Fancy Diamond Shapes Fancy cut diamonds make a very strong statement and are a beautiful and different way to uniquely represent your personality.


Refers to the number of “inclusions” that are found inside a diamond. Inclusions are scratches, trace minerals, or other tiny characteristics that can detract from the way that light bounces from mirror to mirror (known as facets) within a diamond. It is extremely rare to find a diamond without inclusions; when one is found it is ranked “flawless” and is very costly. Inclusions are distinguishing characteristics which represent the uniqueness of each diamond and are often called the diamond's fingerprint because no two stones are exactly alike. The number of inclusions in a diamond is ranked on a scale based on the visibility and location of these little characteristics when the diamond is under 10x magnification.

Two common diamond grading houses are the Gemological Institute of America [GIA] and the American Gem Society [AGS]. Each has its own unique way to rank and ‘grade’ a diamond’s clarity. Below is a chart showing the rankings from Flawless to ‘Included’ and which AGS numbers correspond with which GIA letters so you will be better able to compare “apples to apples” in your diamond search.

Diamond Inclusions "Feathers" look like a bird’s feather in the stone and can be a structural problem if any of the tiny cracks are close to the diamond’s surface. "Pinpoints" look like clear or white bubbles within the diamond and can change the way light is distributed depending on their size. "Carbon Spots are black, brown, or other colored dark dots or specks in the diamond. Many low priced I clarity stones are priced low because of distracting carbon spots in obvious places that cannot be hidden.

"Clouds" are actually just a group of pin point inclusions. Clouds look like empty masses within the diamond and can cause the diamond to be more susceptible to breaking if close enough to the surface. "Needles" look like empty thin tubes and can be very obvious or small. If they are close to the surface or stretch long enough they may cause the diamond to be more susceptible to cracking.


When jewelers refer to a diamond’s carat they are actually referring to the weight of the stone, not the size. In jewelry, the size of stones is measured in millimeters; since diamonds can be cut shallow, deep or ideally it is impossible to accurately convert a diamond’s carat weight into an exact mm size.

However, a very rough conversion can be made. Despite the ability to very roughly convert carat weight to size, the only accurate way to know the true carat weight of your diamond is to weigh it. Thus, 1 carat has become universally known as being a metric weight of 0.02 grams.

The weight of a diamond has the most significant impact on its price. Since the larger a stone is, the rarer it is, one 2 carat diamond will be more expensive than the total cost of two 1 carat diamonds of the same quality. The carat of a diamond is often very important to people when shopping but it is a mistake to sacrifice too much quality for sheer size.

While there is a vast range of other factors that are taken into account with the pricing of each diamond; such as crown angle, cutlet size, cutlet angle, table width percentage, depth percentage, girdle thickness, extra facets, wavy girdle, internal graining, brilliance, fire and many others; we tend to focus on the four c's. There isn't one C that is more important than another. Purchasing a genuine and quality diamond is an individual and magical experience. We are happy to help you decide which C is most important to you! Schedule an appointment with us and we can begin your Brent L. Miller diamond buying experience today!


Traded as early as the fourth century BCE, diamonds were coveted by royalty and the wealthy. Later, caravans brought Indian diamonds, along with other exotic merchandise, to medieval markets in Venice. By the 1400s, diamonds were becoming fashionable accessories for Europe’s elite.

The first diamond engagement ring on record was given by Archduke Maximillian of Austria to his betrothed, Mary of Burgundy, in 1477. Recent evidence supports the origin of the legendary 45.52 carat (ct) blue Hope diamond in India’s Golconda mining area and its sale to King Louis XIV of France (then known as the French Blue diamond) in 1668. In the early 1700s, as India’s diamond supplies began to decline, Brazil emerged as an important source.

Diamonds were discovered when gold miners sifted through gravels on the banks of the Jequitinhonha River in Minas Gerais. Brazil dominated the diamond market for more than 150 years. The discovery of diamonds near Kimberley, South Africa, in the late 1860s marked the beginning of the modern diamond market. Entrepreneur Cecil Rhodes established De Beers Consolidated Mines Limited in 1888, and by 1900 De Beers controlled an estimated 90 percent of the world’s production of rough diamonds. The largest diamond ever found – at 3,106 ct (621 grams) – was recovered from South Africa’s Premier mine in 1905. From it was cut the pear shaped 530 ct Cullinan I diamond, also known as the Great Star of Africa, which is now set in the Royal Sceptre with Cross and housed with the other Crown Jewels in the Tower of London. 


Diamonds were used to engrave gemstones in India by 300 BCE.

Diamonds can be burned. To burn a diamond, it must be heated to between 1290-1650 degrees Fahrenheit. House fires and jewelers’ torches can sometimes reach that temperature.

D-to-Z color diamonds are the most widely used in jewelry, but diamonds come in all colors of the rainbow. For natural colored diamonds, blue, green, orange and red are the rarest; yellow and brown are the most common.

Diamond weight is measured in carats (not carrots or karats). The word carat is derived from keration, the Greek name for the carob tree whose seed was used for centuries as the standard of weighing precious stones. Because the seed could vary slightly in weight, in 1913, carat weight became metric; one metric carat is equivalent to 0.2 grams or 0.007 ounces.

The largest rough diamond, discovered in 1905, is the Cullinan diamond, weighing in at 3,106 carats (ct.)!

**The information and imagery on this page has been provided for educational purposes only and is not the sole property of Brent L. Miller Jewelers & Goldsmiths. Information sourced directly from GIA.

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