Diamond Quality Guide

This Diamond Quality Guide is designed to help jewelry artists understand how diamond quality and value is determined. Diamond grading standards are defined by the GIA (Gemological Institute of America). Diamond experts evaluate diamonds for rarity and beauty using four primary guidelines: cut, clarity, color and carat weight--the 4 C's of diamonds.


The cut of a diamond refers to its shape and to the proportions of how the diamond is actually cut. Diamonds can be cut into many different shapes, reflecting popular taste and also the proportions and quality of the rough stone. Popular shapes include round, oval, square, princess, emerald, baguette and marquise (navette) cuts.

A diamond's overall proportions, as well as the size and placement of its facets, greatly affect how the stone captures and reflects light. Fire Mountain Gems and BeadsĀ® offers diamonds with the classic round brilliant cut.

Standard Facets by Shape
Shape Number of Facets
Round brilliant 58
Oval 58
Princess 58
Emerald 58
Marquise 58
Pear 58
Radiant 70


Clarity is a measurement used to determine the number of inclusions within a diamond. Inclusions reduce the amount of light that can freely reflect through the diamond facets. Most diamond inclusions are not visible to the naked eye. Diamonds graded SI1 or SI2 have small inclusions and can appear flawless to the naked eye. True flawless diamonds are graded FL or IF and are extremely rare.

Inclusions occur inside the stone and are similar to fingerprints, a characteristic that gives us all a special signature. Getting to know your diamond makes the stone a more personal possession and will help you describe and identify the gem. Some inclusions affect the diamond's clarity, making it less brilliant because they interfere with light as it passes through the stone.

Some of the most common types of inclusions include: crystal, mineral, pinpoint and feathers inclusions. Pinpoint inclusions are tiny light or dark crystals in diamonds that appear by themselves or in clusters and large clusters of minute pinpoints can create a hazy area in the diamond. Feathers are cracks within the stone that resemble feathers. Small feathers do not usually affect a diamond's durability unless they reach the surface on the top of the stone (a location that's prone to accidental blows).

Clarity Grade GIA Diamond Clarity Grading Scale
FL No inclusion or surface blemishes (Flawless)
IF Insignificant blemishes (Internally Flawless)
VVS1 Extremely difficult to see at 10x (Very, Very Slight Inclusions)
VVS2 Very difficult to see at 10x (Very, Very Slight Inclusions)
VS1 Difficult to see face up at 10x (Very Slight Inclusions)
VS2 Somewhat easy to see face up at 10x (Very Slight Inclusions)
SI1 Noticeable, easy to see at 10x (Slight Inclusions)
SI2 Very easy to see at 10x, may be visible to the unaided eye (Slight Inclusions)
I1 Obvious at 10x, visible to the unaided eye (Imperfect)
I2 Obvious at 10x, easily visible to unaided eye, beauty/durability somewhat affected (Imperfect)
I3 Prominent inclusions, extremely easy to see with unaided eye, durability affected (Imperfect)


Color is considered by some to be the most important factor in selecting your diamond jewelry, because it is visible to the naked eye. Except for some fancy colored diamonds, the most valuable diamonds are those with the least amount of color. The color scale for transparent diamonds range from D-F (colorless), G-J (near colorless), K-M (faint yellow), N-R (very light yellow) and S-Z (light yellow). Colorless diamonds (D-F) are very rare.


The size of a diamond is measured by weight. One carat, the traditional unit of measure for diamonds, is equal to approximately .2 grams and measures 6.5mm wide. Diamonds of equal weight may appear slightly different in size, depending on their depth and proportions.

The term ''carat'' dates back to traders in the ancient world. A standard weight was required for precious gems as merchants of the ancient Mediterranean and Middle East were dependent on the ability to trade with a reasonably consistent unit of measurement. It was this need that led to the adoption of seeds and grains as widespread units of measurement.

The carob seed and the wheat grain, both of which had been used for food purposes, were found to be ideal units of weight. For centuries, the carob seed remained the weight measurement for precious gems. By the Middle Ages, however, changes in the trade routes had occurred and large centers of trade were now found within Europe. The carat, as it had become known, became linked to 4 grains Troy weight, with the carob seed having been abandoned at some point during the shift of trade centers. The Troy carat was the equivalent of approximately 205 milligrams. This measurement of weight lasted for the carat until the 20th century. It was between 1907-1914 that the carat was married to the metric system of weights. By 1914 the United States officially abandoned the former Troy measurement of 205.3 milligrams for the carat, and adopted the current metric carat measurement of 200 milligrams.

Carat Conversion Chart
mm width Weight - Carat (CT)
1.0mm .005 CT  
1.2mm .008 CT  
1.3mm .01 CT  
1.5mm .015 CT  
1.7mm .02 CT  
1.8mm .025 CT  
2.0mm .03 CT  
2.1mm .035 CT  
2.2mm .04 CT  
2.4mm .05 CT  
2.5mm .06 CT  
2.7mm .07 CT  
2.8mm .08 CT 1/12 CT
2.9mm .09 CT  
3.0mm .10 CT  
3.1mm .11 CT  
3.2mm .12 CT  
3.3mm .14 CT 1/7 CT
3.4mm .15 CT  
3.5mm .16 CT 1/6 CT
3.6mm .17 CT  
Carat Conversion Chart
mm width Weight - Carat (CT)
3.7mm .18 CT  
3.8mm .20 CT 1/5 CT
3.9mm .22 CT  
4.0mm .23 CT  
4.1mm .25 CT 1/4 CT
4.2mm .30 CT 1/3 CT
4.4mm .33 CT  
4.5mm .35 CT  
4.6mm .38 CT  
4.8mm .40 CT  
4.9mm .43 CT  
5.0mm .47 CT  
5.2mm .50 CT 1/2 CT
5.4mm .60 CT  
5.5mm .63 CT  
5.6mm .65 CT  
5.8mm .75 CT  
6.0mm .80 CT  
6.2mm .85 CT  
6.4mm .95 CT  
6.5mm 1.00 CT 1 CT

Diamonds Are a Girl's Best Friend...

Throughout history, diamonds have been used as status symbols and expressions of luxury and love. Diamonds are coveted as gifts, are tokens of romance and represent long-term investments. They are beautiful, precious, timeless, lasting and traditional. Elizabeth Taylor is famous for her life-long love of diamond jewelry. Including the famous Taylor-Burton diamond.

Care and Cleaning

The word ''diamond'' is derived from the Greek word ''adamas,'' meaning invincible. Even though diamonds may be the hardest substance known, they still need proper care and cleaning.

Diamond jewelry is best stored in individual jewelry cases, cloth pouches or in a fabric-lined jewelry box with separate dividers and compartments. This will prevent diamond jewelry from being scratched or damaged--or scratching other gemstone materials they may rest next to.

Be sure to keep your diamonds separated from one another as they are the only material that can cut or scratch another diamond easily.

Lotions, soaps, powders, perfumes and hairspray can diminish a diamond's sparkle and abrasive cleaning products can dull the setting. In general, diamond jewelry can be cleaned in ultrasonic and liquid jewelry cleaners, using a soft bristle brush to clean beneath the setting.

Additional Information

Diamonds have been implicated in international conflicts and weapons trades. Diamond grades are verified by certified GIA (Gemological Institute of America) Graduate Gemologists. Diamond jewelry is made in the USA. All diamonds comply with the Kimberley Process, an internationally recognized certification program that regulates the trade in rough diamonds.

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