Diamond & Gemstone Education - The 4Cs

Every diamond and gemstone is unique. Each mineral has its own story through nature to a fine piece of jewelry or collection; however, diamonds and gemstones share certain traits that allow us to compare and evaluate them, commonly known as the 4Cs


Many gemstones come in a variety of colors; however, some may have a more limited color range. Experts analyze color by three simple traits - hue, tone, and saturation. Hue refers to the gemstone’s basic color such as green, blue, yellow, etc. as well as color blends like blue-green. Tone refers to the color's lightness or darkness, and saturation is the visual intensity of color. Some color ranges can overlap in particular gemstones, therefore a particular tint may be considered "best" for one gemstone and "medium" for another.

Unlike gemstones, the absence of color is most desired and valued for diamonds (Fancy color diamonds such as blues, pinks, etc. are an exception to this rule.) Using the color grading scale set by GIA, the scale ranges from D (colorless) to Z (light yellow or brown.) Diamonds are color graded under controlled lighting and viewing conditions, and subtle color variations can appear invisible to the untrained eye, but these differences can make a significant difference in quality and price.


Many diamonds and gemstones occur naturally deep within the earth and therefore may have unique characteristics that are internal (inclusions) or external (blemishes.)

These natural characteristics in gemstones are what help determine how a gemstone is formed and do not often lessen the beauty or desirability of a gemstone as long as any inclusions are not prominent.

Unlike gemstones. the lack of these "birthmarks" are what increases a diamond's value. Clarity grades for diamonds can range from flawless (FL) to obvious inclusions (I3). These grades are determined by the size, nature, position, color or relief and quantity of characteristics under 10x magnification.

  •         Flawless (FL) - No inclusions or blemishes are visible to a skilled grader using 10× magnification
  •         Internally Flawless (IF) - No inclusions and only blemishes are visible to a skilled grader using 10× magnification
  •         Very, Very Slightly Included (VVS1 and VVS2) - Inclusions are difficult for a skilled grader to see under 10× magnification
  •         Very Slightly Included (VS1 and VS2) - Inclusions are minor and range from difficult to somewhat easy for a skilled grader to see under 10x magnification
  •         Slightly Included (SI1 and SI2) - Inclusions are noticeable to a skilled grader under 10x magnification
  •         Included (I1, I2, and I3) - Inclusions are obvious under 10× magnification and may affect transparency and brilliance

Carat Weight

Not to be confused with "karat" referring to gold purity. Carat is the unit of measurement used to determine a diamond or gemstone weight. One carat is equal to .2 grams and a carat is divided into 100 points; therefore a 67 point diamond weighs .67 carats. A majority of diamonds in the fine jewelry industry are under one carat because very few diamonds over one carat happen in nature and can cause a considerable price increase.

Gemstones have different weight potentials, many can be available up to 15 or 20 carats, others even larger! Like diamonds, gemstones with a limited weight range can also increase in price at certain weights.


Commonly confused with shape, such as round brilliant, princess, pear, etc. In the 4Cs, the cut is what influences the sparkle and brilliance of each diamond or gemstone. Unlike diamonds, gemstones can range from domed cabochon's to intricate carvings to reveal their beauty.

The diamond cut grading system established by GIA is the standard for round brilliants and based on seven components. The first three are brightness (the amount of light reflected from a diamond), fire (the dispersion of light), and scintillation (the pattern of light and dark areas, with flashes of light when diamond is moved - these are appearance based aspects. The remaining four are weight ratio, durability, polish, and symmetry, which pertains to the diamond's design and craftsmanship.

The cut of a diamond or gemstone is one of the most important C's because the cut can influence the color and clarity of the diamond or gemstone because of how the light refracts out of a stone.

Regardless if you are in the market for a beautiful colored gemstone or diamond, the most important factor is how you feel about it.

More information about the 4Cs can be found at GIA.edu and AGTA.org