Diamonds Education

Diamond Carat Weight

       Shallow vs. Deep cut diamonds

A shallow cut diamond that has more surface area on the top will look larger than one that is cut deep with more of its weight below the surface.  While you would think most would want the larger looking diamond, it is actually a combination of factors (which are described in more detail below) that give a diamond the most brilliance.  Some individuals get too caught up on carat weight and do not give the other Cs (color, clarity, and cut) enough consideration.  It is important to have proper balance and weigh this with what is important to you.

        Diamond weight and points

In discussing diamond weight, you often hear the term points used.  For example, you might hear that a diamond is 83 points.  This has the same meaning as .83 carats, because there are 100 points to a carat.  Thus, .50 carats would be the same as 1/2 carat or 50 points, 1.50 carats would be the same as 1 carat and 50 points or one and one half carats. Carat weight and diamond size are not the same thing. Size may actually be greatly affected by cut. Distance in millimeters across the top of the diamond has a huge impact on how big a diamond appears. Once a diamond is set in a ring, it is viewed from the top. Hence, diamonds that have a wider top diameter may seem bigger than stones with a higher carat weight but a smaller top surface area.

Unfortunately, much of a diamond's natural carat weight is lost when it is cut and polished. Often a Gemologist's decision of where and how to cut a particular stone must take optimizing cut, clarity and color into account, sometimes to the detriment of the final weight of a stone. "Magic size" refers to .5, .75, and 1 carat stones. Reaching these optimal numbers greatly impacts a stone's value. For example, a stone that weighs .48 carats may be much less expensive than one weighing .50 carats even though they appear to be almost identical. Hitting a "magic" 1/2, 3/4 or 1 carat sweet spot can lead to a big difference in price.

Diamonds already set in jewelry cannot be weighed; so carat weight is estimated by measuring a stone's outside dimensions. Appraisals or grading reports generally list carat weight measured under these conditions as approximate weight. If the jewelry contains multiple gemstones, the measurement is referred to as an approximate or estimated "total carat weight".

 

Diamond Color

     Diamond "Color" History

The term “color” in white diamonds actually refers to the lack of color present.  Diamonds composed of pure carbon are colorless and extremely rare and costly.  Most diamonds contain nitrogen, boron, or hydrogen all of which impact color.  A majority of white diamonds sold on the market today will contain traces of nitrogen, which causes slight shades of yellow or brown.  Small, subtle differences in color can make a substantial difference in a diamond's value.

Diamond Color Grading System

In a effort to eliminate confusion related to diamond color, the Gemological Institute of America (GIA) implemented the color grading system in the 1950s which is still being used industry wide today.  Diamonds are graded on a scale beginning with the letter D (colorless) and ending with Z (light yellow or brown).  When creating the new color scale GIA chose to start with the letter D as a means of starting over. 

Recommendations for chosing a Diamond Color

Many factors should be considered when deciding on color.  You should always look for a diamond that is as white as possible within your budget.

 

 

Fluoresence

One additional factor in grading the color of a diamond is fluorescence. Fluorescence is the emission of visible light by a diamond when it is exposed to ultraviolet radiation.  Approximately 10% of all diamonds on the market today exhibit fluorescence.  Years ago, these diamonds were referred to as blue white diamonds.  Today, fluorescence on a diamond certificate is divided into five different categories: none, faint, medium, strong, and very strong.  Most diamonds that do fluoresce do so in a blue color; however yellow and other colors are possible.

Fluorescence can be both a negative and a positive.  In the strong and very strong range a diamond may appear oily or cloudy which will greatly reduce the attractiveness and value of the diamond.  However, diamonds of I color and lower can actually look whiter with some fluorescence which; enhances their value.  Better quality diamonds with fluorescence generally sell at a discount to similar ones without.  The reason for this is not that it is less beautiful, but that the general public is under the opinion that fluorescence is a negative.  It is easier for a jeweler to sell a diamond without fluorescence.

Clarity

In the most basic terms, Clarity means clearness. Natural diamonds are rarely perfectly clear. There are external blemishes, internal inclusions, and a myriad of other imperfections seen when viewing a gemstone under magnification. These impurities were developed when minute crystals were trapped within the diamond while it was being formed. To gemologists, clarity defines the degree of imperfection, or measures the size and number of impurities in a particular stone. A flawless diamond that contains no imperfections is so rare, that few jewelers have ever seen one. Since many of the imperfections discovered are invisible to the naked eye, Clarity actually has the least impact of the Four C's on a diamond's beauty. Visible defects on the other hand, have a great impact on value. As a rule of thumb, the greater the number and size of the impurities, the less is the stone's value. All diamonds are unique because of these natural contaminants.

Inclusions

An inclusion is a clarity characteristic either totally enclosed in a polished diamond, reaching or extending into it from the surface, or one that is caused by treatments or the cutting process.  Note - Inclusions caused by treatments or the cutting process may not always be documented on the diamond certificate.

Blemishes

A blemish or external clarity characteristic is on the surface of the diamond only and can be caused by wear, the cutting process, or may be a result of the diamond's crystal structure.  Blemishes play a lesser role than inclusions do when determining the clarity grade, but may affect the polish grade.

 

 

FL:                  Flawless - no blemishes or inclusions under 10x magnification.

IF:                   Internally flawless - no inclusions and only very minor surface blemishes.

VVS1:             Very, very slightly included - very, very small microscopic inclusions extremely difficult to see under 10x magnification.

VVS2:             Very, very slightly included - very, very small microscopic inclusions extremely difficult to see under 10x magnification.

VS1:                Very slightly included - very small microscopic inclusions difficult to see under 10x magnification.

VS2:                Very slightly included - very small inclusions somewhat easy to see under 10x magnification.

These diamonds represent a good value to someone looking for a high quality diamond, as the very small imperfections do not affect the beauty of the diamond.

SI1:                 Slightly included - small inclusions that are easy to see under 10x magnification. 

This clarity is an excellent choice for someone looking to stay within a budget, but wants a diamond that will look as good as a higher clarity diamond except when viewed under magnification.

SI2:                 Slightly included - small inclusions that are visible under 10x magnification.  Depending on their location within the diamond, they may sometimes be visible to the unaided eye without magnification.  SI2 diamonds are attractively priced and typically no visible difference can be seen without magnification.

I1:                   Included - imperfect with inclusions that are obvious to the unaided eye and may affect the diamond's durability.

I2:                   Included - imperfect with inclusions that are very obvious to the unaided eye and may affect the diamond's durability.

I3:                   Included - imperfect with inclusions that are extremely obvious to the unaided eye and pose a definite threat to the diamond's durability.

 

Diamond Cut

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Diamond cutting can be traced back to the mid-1300s when European and Indian gem cutters first began to cut and shape rough diamonds.  Since that time, there have been many cutting methods identified and published.
 

Of the 4Cs, Gemologists believe that cut has the greatest influence on a diamond's beauty.  Diamonds have a unique ability to effectively manipulate light.  This unique quality can only be realized with an extremely high level of accuracy during the cutting and polishing process.  Where nature dictates the uniqueness of color and clarity, humans affect the cut.  While cutting diamond rough, cutters must not only consider the proportions of a diamond, but also the craftsmanship of overall symmetry and polish as well.
 

A diamond's brilliance comes from light entering the crown and reflecting from one facet to another and returning back out the crown.  A diamond that is cut too shallow or too deep will not reflect light properly and the diamond will not be as brilliant as a diamond with an excellent cut.

How a Diamond Handles Light

Diamond Shape

Many people confuse cut with the shape of a diamond. Shape is the basic form of the diamond, meaning whether it's round, square, tear shaped, etc. Cut, as explained above, is the precision cutting of the gemstone to create facets that reflect light. Round diamonds are the industry standards but shape is only limited by the skill and imagination of the diamond cutter. Diamonds that are not round are known as fancy cut diamonds. Popular cuts include princess, marquise, emerald (square), oval, pear and heart-shaped diamonds. Other unusual shapes including triangles can also be found.

 

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