The 4 C's - Understanding diamond quality

DeBeers has done such a great job of educating the public on how to grade a diamond that most women, as well as men, know about The 4 C's: Carat, Color, Cut, Clarity.

At Davenport, we are keenly aware, after handling thousands of stones, that no two diamonds are alike. This is true even when the specs on a certification are almost identical. It is also absolutely possible for one diamond to spec out better than another, though the "lesser" diamond looks better. The grading matters, but the final arbiter of beauty should be your eyes. After all, the reason diamonds are desirable to begin with is not because they are rare, but because they are beautiful.

The 4 C's - Carat, Color, Cut, Clarity:

Carat Weight: How much does the stone weigh? All other things being equal, a larger stone is more rare, and therefore more valuable.
Learn more about the history of the Carat Weight unit of measure.

Color: How colorless is the diamond? The scale used for "white" diamonds runs from D, which is colorless, to Z. White diamonds are more highly valued the more colorless they are. D, E, and F color stones are generally considered colorless. When you get to G, you may notice the tint of yellow if the stone is set in platinum, but not if it's set in white gold or yellow gold. Also, a white stone may have a slight blue fluorescence, which, in everyday wearing situations, may whiten the stone above its official grade. Also important is the metric Cut, which can affect how white a stone looks.

At the other end of the white diamond scale are diamonds with a good deal of yellow. These stones gain in value as they show more yellow. Z color is a "fancy vivid yellow" diamond, the most valuable of the yellow diamonds. Gorgeous
diamonds come in many other colors, including blues, greens, pinks, oranges, and reds. The color of these stones is assessed using different color scales.

Cut: What is the shape of the stone? The most common cuts are round brilliant, oval, pear, marquise, emerald, princess (square), radiant, trillion, and heart. Different styles of cuts, or shapes, affect the brilliance of a stone. Even if two stones have the same cut, one stone may have been cut better and be closer to the theoretical ideal shape for producing the most brilliance. For example, a well cut G colored stone may appear whiter than a poorly cut F, because the increased brilliance masks the body color. This is more common than most people would guess. Diamond color is graded with stones upside down, to eliminate the effect brilliance has in masking the true color.

Clarity: How clear or clean is the stone? Marks in the stone are called inclusions. The more, darker, and bigger the inclusions, the less the value of the stone. Diamond is a special configuration of the element carbon, where the atoms form an octagonal crystal lattice. Carbon is also found in amorphous coal forms and as graphite. Because diamond is often formed by the geological pressurization of coal, black carbon deposits are the most common inclusion in diamonds, appearing as tiny (or not so tiny) black specs. Also common are tiny embedded diamond crystals, which look like bubbles, and crystal needles, made of garnet. If the inclusions are too big or too numerous, they can also affect the brilliance of the stone, and that too, will reduce its value.

The most common clarity scale uses the 10X magnifying loop and the naked eye to evaluate a stone. The scale is as follows:

F: Flawless. No inclusions can be seen when using the 10X loop, and the stone's polish is perfect.
IF: Internally Flawless. There may be small problems with the external polish of the stone, but no inclusions can be seen internally with the 10X loop.
VVS: Very Very Slightly Included. Slight inclusions are hard to find with a 10X loop.
VS: Very Slightly Included. Minor inclusions may be found with the 10X loop but are very hard or impossible to see with the naked eye.
SI: Slightly Included. Noticeable inclusions are easy to find with a 10X loop. In practice, SI inclusions are often also visible with the naked eye, but only if you are looking for them.
I: Included. These inclusions are readily apparent under the 10X loop and often easily seen with the naked eye.

1) Some cuts, for instance, the Princess, are able to use more and waste less of the rough diamond from which it was cut. So a 0.90 carat Round Brilliant could, if cut differently, have been a 1.07 carat Princess cut. Because of this, the price per carat of a Princess cut is usually less than an equivalent Round Brilliant.
2) The same inclusion can lead to a different grade depending upon where it exists on the cut stone. For example, if an inclusion is less obvious because it is off to the side, the stone may be graded higher than if the inclusion were in the center of the table (the flat surface on the top of the stone).
3) Ultraviolet fluorescence is one of those characteristics that can drastically alter the attractiveness of two otherwise identical stones.

Diamond: The 4 C's

The Davenport Organisation
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