Purchasing a Diamond

Ruth Batson of the American Gem Society offers five foolproof tips to consider when you are shopping for a diamond ring.

 When purchasing diamond jewelry, there are four factors that are used to judge the quality of the diamond.

The Four "C's"



Diamonds are measured and sold by weight. The unit of measurement is a “carat,” stemming from the ancient practice in India of using carob seeds to measure small units of weight. A carat is 200 milligrams or 1/142nd of an ounce. It is important not to confuse the gemstone measurement of carat with “karat” used to indicate the purity of gold.

You will see carat (ct) referenced in two ways: rounded off to fractions (½ ct, ⅓ ct, ¾ ct, etc) or in decimals, 0.25ct (¼). 0.33ct (⅓), 0.75ct(¾), etc. It is important to remember that carat is a measure of weight and not size. One diamond may appear bigger than another, but the two may be the same weight.

A diamond’s value increases as weight increases, so a one-carat diamond can easily be worth 3 to 4 times as much as a half-carat diamond of the same quality.


Color of a diamond refers to its physical body of color. Diamonds may appear to be colorless, but most contain at least a trace of body color. The color scale run from colorless to light yellow. The less color in the diamond, the brighter the reflected light, and the higher the color grade. When grading for color, a Gemologist must use a master set of color grading diamonds for comparison.

 D-F: Colorless


G-I: Near Colorless


J-L: Slight Tint


M-R: Very Light Yellow


S-Z: Light Yellow



Most diamonds contain natural inclusions formed during the crystallization process.  Inclusions are trace minerals, fractures, or other tiny flaws.  Gemologists consider the size, position, type, and number of these inclusions when determining the diamond’s clarity grade.  If the inclusions do not impede the light’s passage through the diamond, they will have little impact on the diamond’s beauty.


The rarest of rare diamonds, known as Flawless (FL) diamonds, are those with no internal features and no external features or blemishes visible at ten times magnification. An Internally Flawless (IF) diamond will also have no internal features, but may exhibit a minute scratch left over from polishing.


Very Very Slightly Included

Very Very Slightly (VVS) included diamonds are those with minute inclusions so small that they are extremely difficult for even a skilled diamond grader to see at ten times magnification. A VVS1 diamond may have a single pinpoint, whereas a VVS2 may have a pinpoint or two and tiny feather as its internal features. 


Very Slightly Included

Divided into VS1 and VS2, Very Slightly (VS) included diamonds have minor internal features deemed difficult for a skilled grader to detect at ten times magnification. A VS1 diamond may have a small crystal, a feather, a tiny cloud of inclusions, or a pinpoint or two whereas a VS2 diamond could have for example, a tiny cloud, a few small needles or a small included crystal. In extremely rare cases, very large diamonds, or in significantly transparent fancy shapes like emerald cuts, a VS inclusion may be just barely visible to the unaided eye. 


Slightly Included

Divided into SI1 and SI2, Slightly Included (SI) diamonds are those with features that are obvious at ten times magnification. A typical SI diamond might have a cloud, a feather and an included crystal of another mineral. Neither the diamond's transparency nor face up appearance may be affected by these inclusions. In some rare cases, large diamonds, or transparent fancy cuts, an SI clarity feature may be just visible to the unaided eye. 



Divided in I-1, I-2 and I-3, included diamonds are those with features that are visible to the unaided eye and may even affect the durability of the diamond. Included diamonds may have obvious features such as large contrasting crystals, heavy clouds and distinct cleavages.



The most important factor affecting a diamond’s beauty is also the one element that relies on human skill and expertise. More than any other quality, cut determines the fire and brilliance of a diamond. Even a diamond with perfect color and clarity will have only a dull sparkle if it is cut poorly.

To maximize the diamond’s brilliance, the diamond cutter must place each of the stone’s facets and angles in precise geometric relation to one another. When a diamond is cut too deep or too shallow, less light is reflected back to you. The cut may also refer to the shape of the diamond. The most common diamond shapes are the round brilliant, marquise, pear, oval, emerald, and princess.



Very Good






Three Additional C's 

Now that you know about the 4 C's, you can learn about 3 additional C's to consider when purchasing jewelry: Center Stone, Custom, & Creativity.