Shopping for a diamond may seem overwhelming, but our goal is to educate our customers to help you make an informed decision. Whether you are getting engaged or celebrating your 50th anniversary, we appreciate the importance of your purchase. We will take the time to look at diamonds with you, but more importantly, we deliver honest advice in assessing the features of each stone.

The first step to understanding diamonds is reviewing the Four Cs of diamond grading: Clarity, Color, Cut, and Carat. To choose the perfect diamond for your needs, we will help you weigh each of these factors to determine your priorities.


Clarity refers to the amount and type of inclusions that were trapped within the diamond when the crystal formed. Almost all diamonds have some inclusions, so our job is to decide whether they affect the overall look of the stone. Diamonds with a grading of SI1 and higher should not have inclusions that are visible to the naked eye, while diamonds in the I1 through I3 range have inclusions that are easily visible. In fact, diamonds with I1-I3 grading can be so heavily included that it affects the brilliance of the stone. Most diamonds sold for jewelry are in the range of VS2 through SI2 clarity.

      Viewed under 10x magnification

   Viewed under 10x magnification


The Color in a diamond is judged by the degree of yellow that is visible when viewed through the pavilion or underside. To avoid confusion with older grading systems that used A, B and C designations, the modern color scale begins with D as Colorless, exhibiting no yellow. D, E and F color stones are much more expensive compared to near-colorless (G-J) diamonds. In talking with customers, we find that most people can only see a noticeable yellow in stones graded K-Z.

color chart.jpg


Cut, referring to the diamond's proportions, symmetry, and polish, is the most important feature of a diamond. Even an Internally Flawless, D color stone will look dull and lifeless if it is improperly cut. Keep in mind that the cut grading does not refer to the shape of the stone. Round diamonds exhibit the most brilliance, but fancy shapes such as Cushion, Princess, and Oval can also be well-cut and nicely proportioned.

There are three main features that are affected by the cut of the diamond:

  • Brilliance, or the light reflected from the diamond
  • Fire, which refers to the spectrum of colors flashing within the stone
  • Scintillation, or sparkle

In a properly cut diamond, the light should enter through the table of the diamond and be refracted from the pavilion facets back to your eye. The resulting fire and brilliance create a lively stone even when the girdle is protected by a bezel. If a diamond is cut too deep or too shallow, the light will continue out through the underside of the stone, leaving dark or dead spots regardless of the type of setting.

cut chart.jpg


Carat is literally a measurement of weight used for gemstones. One carat is equal to .20 grams and is written 1.00 ct. Because "carat" measures how much a stone weighs, it can be misleading in terms of size. As seen in our section on Cut, a shallow diamond weighing .75 carats may look larger viewed from above than a deeply proportioned diamond of the same weight. In our opinion, carat weight is the least important factor in choosing a diamond. After balancing your priorities in terms of the clarity, color, and cut of a diamond, carat weight is really determined by the budget available.

round carat.jpg

More recently, you may see a fifth C added to diamond criteria: Certification. Gem grading laboratories like the GIA, EGL and AGL offer written certificates outlining the grade they have assigned to an individual diamond. While gem certificates are useful as a starting point, it's important to understand that how a stone looks on paper may differ from how the same stone actually looks in person. For example, two diamonds with similar gradings can look distinctly different when placed next to each other. There are now several websites selling loose diamonds with gem certificates, but the advantage in working with a reputable professional is that you have an opportunity to compare the actual diamonds, not just their reports. The only way to truly judge a stone's appearance is to examine it with a professional like the goldsmiths at Marc Williams.