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DIAMOND GUIDE

Diamonds are graded and categorized on different characteristics by diamond industry. To know about diamonds, 4c's are like basics of diamonds.

The 4C'S consist of:

  • Cut
  • Clarity
  • Color
  • Carat

These are the basic details Gemologists and jewelers see in diamonds:

 

CUT

Diamond cut is the most important criteria in all 4cs. Brilliance of the diamond depends on how good the cut is. Furthermore cut is defined and categorized in different grades to help the customers to determine the cut of a particular diamond. They are:

  • Excellent
  • Very good
  • Good
  • Fair/poor

Excellent: Excellent cut diamonds reflects the maximum amount of brilliance and fire. It reflects nearly all light that enters the diamond, creating exceptional sparkle and life.

Very good:  Very good cut diamonds properly reflects most of the light that enters the diamond, producing superior fire and brilliance. Under normal lighting conditions, appears very similar to excellent cut, but for a lower price.

Good: Reflects a majority of the light that enters the diamond, for an above average appearance. An excellent value compared to higher cut grades.

Fair/poor: Allows much of the light entering the diamond to escape from the sides or bottom, reducing perceived fire and brilliance. More acceptable in diamonds of less than .75 carats, where differences in sparkle are more difficult to perceive. The diamond may appear noticeably dull and lifeless, even to an untrained eye.

 

CLARITY

Because diamonds are formed deep within the earth under extreme heat and pressure, virtually all diamonds contain "birthmarks". Small imperfections of the diamond (called inclusions), or on its surface (called blemishes). If you think about the incredible amount of pressure it takes to create a diamond and the fact that natural diamonds are not made in a sterile laboratory, it is not surprising that most diamonds have flaws.

The position of an inclusion affects how easily it can be seen. Diamond cutters make every effort to cut a stone so that inclusions are not visible through the table of the finished diamond. The preferred position for inclusions is under the bezel facets or near the girdle because they are harder to see there.

Clarity is determined by following grades

Flawless - Flawless diamonds have no inclusions or flaws when viewed under 10x magnification by a trained grader. A diamond can have naturally confined to the width of the girdle, extra facets on the pavilion that are not visible face-up, laser inscriptions confined to the girdle and internal graining that is not white, colored or reflective.

Flawless (IF) - IF diamond has no inclusions, only blemishes when viewed under 10x magnification.

Very, Very Slightly Included (VVS1 and VVS2) – VVS1 diamonds contain minute inclusions that are difficult for a skilled grader to see under 10x magnification. Inclusions of VVS1 diamond is extremely difficult to understand, respond to, or cannot be seen through the pavilion. VVS2 inclusions in diamonds is very difficult to detect. VVS2 diamonds usually have a pinpoint or two, but properties such as tiny chips or bearded girdle might be present in VVS2 according to their visibility.

Very Slightly Included (VS1 and VS2) - VS clarity diamonds contain minor inclusions ranging from difficult (VS1) to somewhat easy (VS2) and can be seen under 10x magnification. Typical inclusions of VS diamonds are small crystals, feathers and specific groups of pinpoints.

Slightly Included (SI1 and SI2) - SI clarity diamonds contain visible inclusions that are easy (SI1) or very easy (SI2) to see under 10x magnification. Typical inclusions such as crystals, feathers and clusters are identified in the center of the diamond.

Included (I1, I2, and I3) - Diamond Clarity Range "I" contain inclusions that are visible under 10x magnification. These inclusions can often times be seen face-up without magnification, sometimes affect the stone's durability and can be so numerous or large that they affect transparency and brilliance.

The clarity is typically assigned by a first impression or at first glance. The grader notes whether the inclusions are easy, difficult or very difficult to see when they first look at the stone. The clarity grade of most diamond s is determined in less than 2 minutes. The exception to this is in Internally Flawless and Flawless diamonds, which take considerable examination to assign such a high and valuable grade.

 

COLOR

When most industry experts discuss the color of diamonds, they are generally pointing to lack of transparency or color of the diamond. Diamonds are made of 100% pure carbon without impurities thus are completely colorless diamonds. However, almost all diamonds contain some extent of color impurity caused by traces of nitrogen, boron, hydrogen or other elements. Most diamonds suffer only traces of nitrogen, which produces a pale yellow or brownish color.

Method of diamond color grading

To grade color of the diamonds, they should be free, because if the diamond is in the metal, the metal will affect the color we perceive. For example, a slightly yellow diamond could might glitter more yellow if set in yellow gold, look less yellow set in white gold or platinum. .

Diamonds are placed table-down, pavilion up, and magnified under 10X loupe.

Lettering system from D to Z is used to determine the amount of color in each diamond with D awarded only to rarely completely colorless diamonds.

Grades of Diamond colorColorless diamonds and diamonds that are yellow or yellowish brown are grouped into the following categories. These varieties do not apply to fancy colored diamonds - they have their own grades.

D-E-F

Colorless.

G-H-I-J

Almost colorless.

K-L-M

Pale in color, usually yellow.

N-O-P-Q-R

Typically slightly tinted yellow. The color can be seen with the naked eye.

 

CARAT

It's easier to understand this C of all "4Cs". Weight of a diamond is directly related to the size, and although incorrect, these terms are sometimes used interchangeably. A unit of weight for diamonds and other gemstones is carat. It is a term that is derived from the use of an ancient 'Carob' seed in measuring small weights. Table of common weight-related terms are given below.

 

Carat weight             

Equivalent weight

One carat

 

200 milligrams           

0.200 grams (There are 5 carats in 1 gram and 142 carats to 1 oz.)

 

A carat is divided into 100 parts each called a point. So 1 carat = 100 points.

 

Three quarter carat

75 points

Half Carat

50 points

Quarter Carat   

25 points

 

POLISH

The quality of diamond's surface condition is referred by polish grade of a diamond. It indicates the level of smoothness created while cutting and polishing process of the diamond. As a result the polishing and cutting process play an vital role in determining the polish grade including the cut grade.

Polish grade is measured on a scale of Excellent, Very Good, Good, Fair, Poor. It signifies the smoothness of different diamond facets. More the blurred and dull appearance, lower the grades. So it's always recommended to buy a diamond of good to excellent grade.

Here how Polish grade is measured according to GIA grading system: 

Excellent: Diamonds with Clear lustre with no to minor mark which even a 10x magnified lens can't detect comes under 'Excellent' grading scale.

Very Good: Diamonds with few tiny marks which are difficult to see under 10x magnification comes under 'Very Good' grading scale.

Good: Diamonds with visibly marks under 10x magnification comes under 'Good' grading scale.

Fair: Noticeable marks can be seen under 10x magnification which can affects the lustre of diamond when viewed with the unaided eye.

Ideal: Brushes can be seen even with naked eye. Lustre of diamond appears dull & blurred for the diamonds of 'Ideal' polish grade.
 
 

SYMMETRY

Symmetry refers to the alignments of facets & equality between them. This includes misaligned facets, off-center tables & culets and tables not parallel to girdle lines.

Symmetry of a diamond effects the ability of diamond to reflect light that travels into diamond thereby affects its brilliance.

Here how Symmetry grade is measured according to GIA grading system:

Excellent: A perfect symmetrical diamond with all facets aligned correctly comes under 'Excellent' grading scale.

Very Good: Diamonds with defects still unable to notice under 10x magnification comes under 'Very Good' grading scale.

Good: A minor defect if visible under 10x magnification makes the diamond to fall under 'Good' grading scale.

Fair: A reasonable defects are noticeable under 10x magnification and can be visible with naked eye.

Ideal: Diamonds with defects which can easily be detected by naked comes under 'Ideal' grading scale.
 

FLUORESCENCE

Fluorescence in diamond is due to the traces of mineral boron present in earth as this crystallization process is occurring, the diamond will fluorescence. It can be observed under a long wave ultra violet light. When a diamond has fluorescence it is either faint, medium, strong or very strong. Stronger the fluorescence of diamond, lesser the value.
 

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