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The 4Cs of Diamonds and Why They Matter

Understanding the 4cs

What are the 4 C’s of Diamonds and What Do They Mean?


Carat is a metric unit equal to 0.20 grams, and is used as the standard unit of weight of diamonds and most other gems. To simplify this further, it’s the size of the diamond when it’s loose, meaning not in the mounting of the ring. If other factors are held equal, the more a loose diamond weighs, the more valuable it will be. In the diamond trade, prices are expressed as a price per carat. The Carat Weight has the biggest impact on the price of a diamond. For example, a two carat diamond is more than double the price of a one carat diamond. In the diamond trade, size is less important than the quality of the diamond; consumers tend to prefer larger carat weights because of their higher status. Large carat weight alone, though, does not alone signify a better ring. "Total Weight,” often abbreviated as “T.W.,” refers to the total carat weight as measured when the gems are loose and unmounted. This can often be misleading as evidenced by the following example: a ring with emeralds and sapphires and diamonds could say “Emerald t.w. = 0.25 cts., Sapphires t.w. = 0.31 cts., Diamonds t.w. = 0.75 cts.” This could mean there were 5 emeralds, 7 sapphires and 50 diamonds as easily as it could mean that there were 2 emeralds, 2 sapphires and 2 diamonds, because the T.W. does not consider the number of gems contained within the jewelry.


The color of a diamond has the second biggest impact on its price, after carat weight. Though many diamonds appear colorless, most have at least a trace of yellow or brown color. Diamond expert grade these “colorless” diamonds by deciding how closely a stone approaches colorlessness. This is absence of color is an indication of higher value because diamonds act like prisms, separating white light through them into a spectrum of colors; the more transparent the diamond, the wider the spectrum of colors, and subsequently, the higher the value. Diamonds in colors such as blue, pink, purple, or red are referred to as “fancy color” diamonds and are incredibly beautiful, but more expensive due to their rarity. If a diamond does not have enough color to be called “fancy,” then it is graded on a scale of colors ranging from Colorless to Light Yellow, “D” through “Z.” A diamond classified as “D” is considered colorless, and if the color is more intense than “Z,” it is considered fancy.


Clarity” describes the absence of presence of internal and external flaws. A perfect stone with perfect clarity is rare, although some flaws cannot be seen without using magnification. The clarity of a diamond is understood in grades.

Diamond grades are as follows:


  • FL - Flawless
    These stones have no imperfections inside or on the outside of the stone under the magnification of a loupe of 10X magnification.

  • IF - Internally Flawless
    This grade is awarded to diamonds with no internal flaws and only minor external blemishes.

  • VVS1, VVS2
    Very Very Slightly Imperfect—These stones have very, very small inclusions, which are extremely difficult to see under a loupe of 10X magnification.

  • VS1, VS2
    Very Slightly Imperfect—These stones have very small inclusions, or imperfections, which are slightly difficult to see under a loupe of 10X magnification.

  • SI1,SI2
    Slightly Imperfect—These stones have inclusions, which are fairly easy to see with a 10X magnification, and can be seen with the naked eye.

  • I1, I2, and I3
    Imperfect—These stones have inclusions ranging from moderately visible to very easily seen to the naked eye.


The cut of a diamond refers to the way the diamond was faceted to allow light to reflect from it. In a well-cut diamond, light enters the diamond and reflects straight back to the viewer’s eye. The width and depth can have an effect on how light travels within the diamond, and how it exits in the form of brilliance. Diamond cutters will occasionally sacrifice the ideal cut to create the largest possible diamond, making a cut too deep or too shallow to allow the light to reflect as well as possible. If the cut is too shallow, the light is lost out of the bottom, causing the diamond to lose brilliance. Contrarily, if the cut is too deep, light escapes out of the sides of the diamond, causing a dull or dark appearance. Polish and symmetry are also two important aspects of the cutting process. The “polish” grade describes the smoothness of the diamond’s facets, while the “symmetry” grade refers to the alignments of these facets. For the most beautiful diamond, look for a symmetry grade of excellence (EX), very good (VG), or good (G). Avoid diamonds with symmetry grades of fair (F) or poor (P).