The The Four C's

 

Color, Clarity, Carat Weight, and Cut

A diamond is possibly the most precious object many people will ever see. A diamond that can be held in the palm of your hand can easily be worth more than the most expensive house in a large city. Over many years, professional diamond buyers have created very precise standards for grading and comparing the characteristics of individual diamonds in order to set their values. Some of the many considerations used in this process include the rarity of certain characteristics, beauty, quality and market demands. In today's market these standards are more precise than those applied to almost any other consumer product. It is these very slight differences in a diamond's characteristics that can cause enormous differences in a stone's value, and desirability. The main standards for the grading and valuing of diamonds has become widely referred to as the "Four C's," defined for you below. There are also many subtleties, which go beyond these factors. You might say the "devil is in the details" and these details, are little understood and seldom discussed in the retail sales arena.

 

 





Color

If a diamond crystal was 100% pure carbon, with a perfectly uniform isometric structure it would be absolutely colorless. However most diamonds will pick up a few atoms of other substances in their growth process. There are more than 25 known impurities that contribute to a diamond's color, yet in white diamonds these impurities represent no more than 5% of the stone's weight. The most common impurity in a diamond crystal is nitrogen, which imparts a yellow tint to the crystal. Different substances and different crystal growth structures will cause color variations as diamond crystals form.

Many people believe that most diamonds are colorless or near colorless due to the fact that most diamonds sold in retail trade are very nearly colorless to slightly yellow, brown, or gray – the normal range for white diamonds. However diamonds can and do occur in every color under the rainbow (very few are truly colorless). Diamonds with strong or distinct tints which do not fall within the normal range of white diamonds, D through Z, are called fancy colors. I will discuss only white diamonds on this page, those diamonds which, when properly graded, fall between D and Z on the scale developed by the Gemological Institute of America ( G.I.A. )

The G.I.A. Color Scale 

GIA’'s color scale begins at D (colorless) and runs to Z (light yellow). Each letter represents a range of color, not an exact color.

Example: If a diamond is correctly graded as an "H" in color, it may be a low "H", very near an "I" color or a high "H" very near a "G" in color.

To arrive at a color grade the grader must have a master set of stones to use as a comparative baseline and the correct lighting source. The grader then places the subject stone approximately one centimeter from the master stone under the proper light source and visually compares the two stones. This process is repeated until the grader determines a match. The color grade affects the value differently in various shaped and sized diamonds. It would be safe to say that all factors, other than color, being equal in two diamonds, a movement towards colorless would tend to increase the value of that stone.





Clarity

The growth process of a diamond does not occur all at once, or in an even space of time. It occurs in phases over time, and within these phases of growth the diamond crystal is subject to great variances in temperature, pressure and cooling rates. As this growth or crystallization occurs, different types of fractures may form in the crystal, or other minerals may be present and become trapped within the diamond crystal. Twenty-five different minerals are know to include diamonds, the most common of which is red garnet. The size, number and position of these included minerals along with the fractures, clouds, tension cracks, and polishing marks which might remain from the cutting process compose the Clarity Grade of a diamond.

The diamond loupe is the basic tool used in clarity grading and it is defined as a triplet ten times magnifying lens of high quality, corrected for chromatic and spheric aberration. The lens must be large enough to see an entire stone of 4 to 5 carats.

The classification system for clarity grades of polished diamonds that is in use in America today was created by the Gemological Institute of America . It is accepted worldwide with slight technical differences in just a few countries.

    *SI3 in Not Reconized by GIA


  • F - Flawless
    Diamond is free from internal and external flaws when tested by an expert under a microscope with ten times magnification. Exceptions are: small naturals or extra facets, minor rough places on the girdle that are not visible from the crown which flatten the girdle.

  • IF - Internally Flawless
    Diamond is free from internal flaws tested by an expert under a microscope with ten times magnification. External features should be so slight that they can be easily removed by polishing with very little weight loss.

  • VVS1 - Very, Very Small 1
    There must not be any inclusions in the field of the table. Very, very small inclusions are allowed in the rest of the stone. External faults must be very minimal.

  • VVS2 - Very Very Small 2
    Very,very small inclusions anywhere in the stone, only very small external defects allowed.

  • VS1 - Very Small 1
    Only the smallest inclusions are allowed in the field of the table, only small faults elsewhere in the stone. Small external faults.

  • VS2 - Very Small 2
    Very Small internal faults, also allowed under the table. Small external defects.

  • SI1 - Small Inclusions 1
    Small internal faults, also under the table as long as not too obvious, not visible to the unaided eye. Some external features may be present.

  • SI2 - Small Inclusions 2
    Small, easily discernible faults in the table, not visible to the unaided eye. Some definite external features.

  • I1 - Imperfect 1
    Easily seen with loupe, but visible to the unaided eye with difficulty through the crown, does not influence the brilliance. Definite external flaws.

  • I2 - Imperfect 2
    Large and numerous inclusions, just visible to the unaided eye through the crown. Diminished brilliance. Definite external faults.

  • I3 - Imperfect 3
    Large and numerous inclusions, easily visible to the unaided eye through the crown. Diminished brilliance. Definite external faults

 





Carat Weight

Diamonds in the modern market place are weighed in "Metric Carats". A Metric Carat is equal to 0.2 gram or just a little more than 0.007 (seven thousandths) ounce avoirdupois, the same type of ounce used to measure produce at the grocery store. A Metric Carat, hereafter referred to as a carat, is still not precise enough for weighing something so precious as a diamond. Diamond weights are therefore measured to the thousandth of a carat and then rounded to the nearest hundredth of a carat. Each one one-hundredth of a carat is commonly referred to as a point. 

Example: A diamond which has a carat weight of 0.78 carats will often be called a 78 point stone or a 78 pointer. 

In the case of a diamond which has a weight over one carat, the measure will be express in whole and decimal fractions. 

Example: A diamond which has a carat weight of 1.24 carats will often be called a 1- point 24 or 124 pointer. 

Due to the high value of even lower grades of diamond it is important that the true weight of the diamond be known. There are several devices that are accepted for the weighing of diamonds. The diamond balance, basically unchanged in the last 3500 years, uses counterweights placed in one pan and the diamond placed in the other. A simple device, but when used correctly can produce very accurate results. It is more likely that you will find today's jeweler using an electronic diamond scale, simple and accurate, the readings are normally displayed in a digital format. Do not consider buying a diamond unless it can be weighed in front of you.




Cut

 

The art of diamond cutting turns a rough diamond, a yellow, gray or brown unattractive pebble, into a highly reflective, light scattering prism of brilliance.

The way in which a diamond has been cut and polished is the primary factor determining how brilliant and beautiful a diamond will be. Yet, of the Four C's, I believe the cut to be the least understood by consumers and the characteristic that most often causes a buyer to fall short of their desired goal.

Many people I speak with tend to confuse the term Cut with the Shape of the stone, i.e.( Round, Marquise, Princess, etc.). In the diamond market when someone refers to the Cut or Make of a diamond, they are trying to describe how closely to an ideal proportion and finish that a diamond has been fashioned. These ideal proportions vary from one shape diamond to another and there are often differences of opinion on what proportions are ideal for even a single diamond shape. It is very difficult for an untrained buyer to judge the quality of Cut. Extremely small deviations in diameter, depth, polish, and symmetry among other factors, can create large disparities in a diamond's value. In the following pages I have listed what I believe to be the most sought after proportions for the more popular shaped diamonds at this point in time. I stress that these are my opinions and other jewelers may have opinions which differ from mine. I do believe that the information I supply will help you bypass the grossly misshapen, commercial quality diamonds.

Effective January 1st, 2006

The Gemological Instute of America "GIA" will now include a Cut grade on Diamond Grading Reports for Round Brilliant Diamonds.

More information on GIA's new cut grading system.