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The Four Cs of Diamonds

Three Round Cut Diamonds

Fine diamonds are among the world's most coveted gemstones. To determine a diamond's value, experts use the Four Cs—cut, color, clarity, and carat weight.


A diamond’s overall proportions, as well as the size and position of its facets, make up the cut. The consistency and balance of these can greatly affect how the stone captures light and reflects it back to the eye.

Studies have been conducted to find the optimum proportions of a diamond’s cut so that it has the greatest amount of sparkle. If its cut falls within these parameters, it is considered an ideal cut. Commonly used terms regarding refraction and light:

  • Brilliance—the combination of all of the white light reflected from the surface and the inside of the diamond.
  • Dispersion—flashes of color you see in a polished diamond. Dispersion is also known as fire.
  • Scintillation—flashes of light you see when the diamond, the light, or the observer moves.
Shallow cut diamond diagram

Too Shallow

If a diamond is too shallow, light will escape from the bottom of the gemstone.

Ideal cut diamond diagram


When a diamond is cut with the ideal proportions, light enters the diamond and is returned through the top of the diamond.

Deep cut diamond diagram

Too Deep

If it is cut too deep, light will escape from the pavilion.


One factor that determines the value of a diamond is its color. With the exception of fancy-colored diamonds, the most valuable diamonds are those with the least color. Although many people think of gem-quality diamonds as colorless, completely colorless diamonds are very rare.

Each letter grade represents a range of color that is determined by a manual process of comparing the diamond to a master set.

Colorless Near Colorless Faint Yellow Very Light Yellow Light Yellow Fancy


A diamond’s clarity is measured by the existence or absence of visible flaws. Tiny surface blemishes or internal inclusions, even those seen only under magnification, can alter the brilliance of the diamond and thus affect its value.


Flawless: No internal or external clarity characteristics


Internally Flawless: No internal clarity characteristics


Very, Very Slightly Included: Difficult to see under 10X magnification

VS1, VS2

Very Slightly Included: Inclusions not typically visible to the unaided eye

SI1, SI2

Slightly Included: Visible under 10X magnification and may be visible to the unaided eye

I1, I2, I3

Included: Inclusions visible to the unaided eye

Carat Weight

Carat refers to the diamond’s weight. You may also hear the weight of a diamond referred to in points. One carat is equivalent to 100 points, so a 75-point diamond is equal to 0.75 carats. Because they are rarer, larger diamonds have greater value per carat. Therefore, the price of a diamond rises exponentially in regards to its size.

Download Carat Size Chart (PDF)

Carat to Millimeter Size Reference

MM 4.2 5.2 5.6 5.8 6.5 7.0 7.4 7.8 8.2 8.8 9.4 10.4 11.2
Diamond icon Diamond icon Diamond icon Diamond icon Diamond icon Diamond icon Diamond icon Diamond icon Diamond icon Diamond icon Diamond icon Diamond icon Diamond icon
CT 38 12 58 34 1.0 1.25 1.50 1.75 2.0 2.50 3.0 4.0 5.0
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7/22/2024 Market Prices:
Gold 2392.70 Platinum 952.00 Silver 29.07