What your brother is most likely talking about is the "four Cs" -- cut, clarity, carat and color. Most diamonds never reach the consumer market because they are too flawed (often, these diamonds are used for industrial purposes -- as an abrasive, for drill bits or for cutting diamonds and other gems). The diamonds that do make it to market are judged mainly on these four factors to determine their value.
- Cut - This term refers to the way in which the diamond has been, literally, cut -- its geometric proportions. When a diamond is cut, facets are created and the diamond's finished shape is determined. The number of facets has a direct impact on the brilliance, or "fire," of the diamond. Diamonds, as the following drawing illustrates, can be cut into many different shapes. The most popular shape is the round diamond, probably due in large part to the brilliance this shape can provide.
The shape of a diamond can impact the brilliance and overall impression of size.
- Clarity - This term refers to the measurement of a diamond's flaws, or inclusions that are seen in the diamond. Clarity levels begin with Flawless and move down to Very Very Slight (VVS), Very Slight (VS) and Slightly Included (SI).
Now That's a Rock!
The largest diamond ever found was unearthed in 1905 in Transvaal, South Africa. The Cullinan diamond was measured at 3,106 carats -- that's 621 grams!
- Carat - This term refers to the weight of a diamond. One carat is equal to about 200 milligrams. It is important not to confuse the weight of a diamond with its dimensions. Say you have two 1-carat diamonds that are both cut in the round shape -- one may appear to be larger than the other. Certain cuts allow you to see more surface area of the diamond than others.
- Color - The word "colorlessness" could be substituted for the term "color." In referring to transparent diamonds, the color scale runs from D to Z, beginning with Icy White -- the color, or lack thereof, of the most expensive diamonds -- and ending with a light yellow.
Other unique qualities of a diamond include its transparency, luster and dispersion of light. A diamond that is created from 100-percent carbon will be completely transparent. Diamonds often contain other elements that can affect the color. Although we often think of diamonds as being clear, there are also blue, red, black, pale green, pink and violet diamonds. These colored diamonds are the rarest ones.
Here are some interesting links: