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4 C's of Diamonds

Learning 4 C’s of Diamonds at Costello Jewelry Company


Diamond Color

While people think of diamonds as pure, clear stones, very few diamonds can really claim to be “completely colorless.” Because of the way that diamonds are formed in nature, they usually have other elements baked in during their creation. The most common of these is nitrogen, which causes shades of brown or yellow to appear. So, as the brown and yellow tones become more easily apparent, the rarity and cost decrease. The exclusivity of colorless diamonds leads to them commanding a higher price in the market.

The GIA scale for color ranges from the completely colorless D to the extremely yellow Z. However, colors other than yellow, such as blue and red, and richly-saturated tones of yellow cause the diamond to be labeled as “fancy.”

Diamond Clarity

Clarity refers to the lack of inclusions in a diamond. As with color, since diamonds are formed in uncontrolled environments, there are many opportunities for the inner structure of a diamond to be disrupted during its growth. These inclusions can be caused by cracks, voids, or foreign materials trapped in the stone during its formation. The most common of these materials are black carbon, olivine, garnet, silica, calcite, and iron. The amount, type, and placement of inclusions determine a diamond's clarity grade and shift the cost accordingly.

The GIA clarity scale has 11 categories, ranging from F (flawless), which means that a skilled grader using 10x magnification can’t find any flaws; to I3 (included-3).

Diamond Cut

The cut of the diamond isn’t the same as the shape. When we talk about the cut of a diamond, we’re referring to the quality that’s gone into geometrically assembling the crown, girdle and pavilion of a diamond to maximize the internal reflectivity of the stone. A well-cut diamond is one that has a huge amount of fire and sparkle, and when it comes to picking a diamond, cut may be the one quality that has the most effect on the overall beauty of the stone.

GIA grades cut from “excellent” to “poor” using a seven-point measuring scale: brightness, fire, scintillation, weight ratio, durability, polish, and symmetry.

Diamond Carat Weight

The last “C” on the list is the easiest to comprehend. Carat refers to the weight of a diamond, with one carat weighing 0.2 grams. Each carat is divided into 100 points, which means that a 150-point diamond would be 1.5 carats. Carat may be a universal measurement for weight, but depending on the shape of the stone, you may find that a diamond can appear larger or smaller. For example, the emerald-cut diamond will look far larger than a round-cut diamond of the same carat weight.

Learn about the 4 C’s of Diamonds at Costello Jewelry Company

As one of the premier dealers of loose diamonds in our area for over 40 years, Costello Jewelry Company is your source for information about every woman’s favorite jewel. If you’d like to find out more about loose diamonds or the diamond jewelry we offer, contact us at (630) 790-3272 or visit our Glen Ellyn or Naperville, Illinois showrooms today!

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