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The Vocabulary of Diamonds

EDUCATION

The vocabulary of a certain trade is the key to understanding.  Once you know the correct terms you can dissect any subject.  In this section we will provide you with some basic vocabulary and information to help you learn about the jewelry industry so that you can make an informed purchase.  We are here to answer any of your questions.

 

DIAMONDS

Above all other gemstones, Diamonds elicit a human response that transcends time and place.  First found in India and used as religious icons, there is no surprise that early humans believed diamonds to have mystical and religious powers.  From this first discovery during the 1st century B.C., diamonds have been treasured by all civilizations that have followed.

A diamond is crystalline carbon in which the carbon atoms bind together in a close-packed cubic arrangement which gives the diamond structure that of an octahedron.  This natural structure makes the diamond extremely hard, rating the highest of 10 on the Mohs Scale of Mineral Hardness.  Each diamond rough is unique from the next and is categorized by what is called the Four C’s: Carat, Cut, Color and Clarity.  The standard in grading these four properties was developed by the Gemological Institute of America (GIA) in the 1940s and ’50s.   GIA developed the 4Cs and the GIA International Diamond Grading System™ to objectively compare and evaluate diamonds.

Logically, the Four C’s directly affect monetary value of a diamond.  As the quality and size increases, so does the value.

Here is more about the Four C’s:

 

CARAT

Diamonds, as all other gemstones, are measured using the metric unit of mass the carat.  One carat is equal to 0.20 grams and can be divided into 100 points.  For example a 75-point diamond weighs 0.75 carats.  The carat is named for the carob seed.  These seeds had a fairly uniform weight and were used by early traders as counterweights in the balance scales.  The carat was then adopted by the metric system to represent 200 milligrams.

 

CUT

The cut of the diamond depends upon ideal proportions and accurate alignment of the facets in order to create light refraction which makes the diamond sparkle.  The proper cut can add brilliance (the total light reflected from a diamond), fire (the dispersion of light into the colors of the spectrum, and scintillation) and the flashes of light when a diamond is moved – the sparkle.

The shape of a diamond affects the cut more than any other factor.  The most common shape is the round brilliant and all other shapes are known as fancy shapes.  Fancy shapes include: marquise, pear, oval, emerald, heart, cushion, triangle and many others.  Once the shape of the diamond is determined from studying the rough the cutting of the diamond begins.  Each shape requires mathematical guidelines for the angles and length ratio in order to maximize the amount of light reflected within the diamond.  Ratios that are off, often will allow light to escape through the sides or the bottom of the diamond instead of directing light through the crown.

A round brilliant diamond contains 58 facets. Each facet affects the ability of the diamond to reflect light.  The Table is the large, flat surface on the top of the diamond.  The Crown contains 33 facets and is the area between the table and the girdle.  The Girdle is the middle of the diamond where the crown and pavilion meet.  Many girdles have 32, 64, 80, or 96 facets; these facets are not counted in the total.  Below the girdle is the Pavilion which contains 25 facets.  The pavilion meets at the bottom the diamond creating the Culet.

The table, crown, girdle, pavilion and culet make up all shapes of diamonds.

The GIA grades the cut of a diamond on a scale starting with Excellent, Very Good, Good, Fair and Poor.  This grading is dependent on the diamonds proportions, symmetry and polish.

 

COLOR

Diamonds are graded by the lack of color.  The less color you see in a diamond the better quality it is (with the exception of fancy colored diamonds.)  Natural chemical impurities (Nitrogen and Boron atoms that bond to the carbon atoms) within the earth affect the color of a diamond.  The GIA developed the color-grading scale based on the alphabet and starting with the letter D and continuing to Z.  Each letter has a defined color and is color-graded by comparing the diamond to stones of known color under controlled lighting and precise viewing conditions.

Colorless diamonds are graded D-E-F

Near colorless diamonds are graded G-H-I-J

Faint yellow or brown diamonds are graded K-L-M

Very light yellow or brown diamonds are graded N-O-P-Q-R

Light yellow – S-T-U-V-W-X-Y-Z

Fancy colored diamonds are not graded on the GIA’s D-Z color grading system. They are classified in a separate system developed by the GIA in the 1970’s.  The scale is not based upon letters but the description of the color saturation.  As opposed the white diamonds, the more color that is present the more desirable it is.  The scale ranges from Fancy Vivid, Fancy Intense , Fancy Deep, Fancy, to Fancy Light.  Fancy colored diamonds span the spectrum of color from yellow to blue to pink to green to black.  Some of the more recognizable and popular fancy colored diamonds are yellow diamonds or “Canary” while some of the most rare are red diamonds.

What properties make a diamond fancy colored?  Yellow diamonds appear yellow because of nitrogen molecules present in the structure that absorbs blue light.  Blue diamonds are due to boron particles that become trapped in the diamond’s crystal with very little trace of nitrogen.  Green diamonds are the result of millions of years of exposure to radioactive materials in the Earth’s crust.  Pink diamonds remain a mystery to those in the gem world. What is known is that the color saturation is not due to trace elements within the diamond.  Red diamonds are also a bit of a mystery because they are so rare and very few true red colored diamonds are available to study.

 

CLARITY

The clarity of a diamond refers to the cleanliness of the diamond.  Most diamonds have small imperfections that were present at the formation of the crystal.  These imperfections or inclusions for the most part will not impair the diamond’s ability to reflect light and cannot be seen without the use of a high-powered microscope and training. Internal imperfections are referred to as inclusions and external imperfections are known as blemishes.  The clarity of a diamond is measured by the lack of these imperfections and graded on a scale developed by the GIA.  The scale is as follows:

Flawless (FL) – No inclusions or blemishes are visible using 10X magnification

Internally Flawless (IF) – No inclusions only blemishes are visible using 10X magnification

Very Very Slightly Included (VVS1/VVS2) – Inclusions are difficult for a skilled grader under 10X magnification

Very Slightly Included (VS1/VS2) – Inclusions are clearly visible under 10X magnification but are classified as minor

Slightly Included (SI1/SI2) – Inclusions are clear under 10X magnification

Included (I1/I2/I3) – Inclusions are clear under 10X magnification and can affect brilliance.

Call William Noble, the premier buyer and seller of estate jewelry in Dallas, for more information.  214.526.3890 or contact us at sales@williamnoble.com


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