Diamond Guide

In finding the right diamond is to decide on the basic 4 Cs :

Diamond Cut

Diamond Cut
  • Diameter
    The width of the diamond as measured through the girdle.
  • Table
    This is the large, at top facet of a diamond. Crown The upper portion of a cut gemstone, above the girdle.
  • Girdle
    The narrow rim of a diamond that separates the crown from the pavilion. It is the largest diameter to any part of the stone.
  • Pavilion
    The lower portion of the diamond, below the girdle. It is sometimes referred to as the base.
  • Culet
    The tiny facet on the pointed bottom of the pavilion, which is the portion of a cut gem below the girdle.
  • Depth
    The height of a gemstone, from the culet to the table.
1. Cut

Diamond cut is perhaps the most important of the four Cs, so it is important to understand how this quality affects the properties and values of a diamond. A good cut gives a diamond its brilliance, which is that brightness that seems to come from the very heart of a diamond. The angles and nish of any diamond are what determine its ability to handle light, which leads to brilliance.

The techniques for cutting diamonds have been developed over hundreds of years, with perhaps the greatest achievements made in 1919 by mathematician and gem enthusiast Marcel Tolkowsky.

Tolkowsky defined the ideal dimensions as:

  • Table percentage (table diameter divided by overall diameter) = 53%
  • Dept percentage (overall depth divided by the overall diameter) = 59.3%
  • Pavilion Angle (angle between the girdle and the pavilion) = 40.75%
  • Crown Angle (angle between the girdle and the crown) = 34.5%
  • Pavilion Depth (depth of pavilion divided by overall diameter) = 43.1%
  • Crown Depth (depth of crown divided by crown diameter) = 16.2%

The culet is the tiny point or facet at the bottom of the diamond. This should be a negligible diameter, otherwise light leaks out of the bottom. Tolkowsky's ideal dimensions did not include a culet. However, a thin culet is required in reality in order to prevent the diamond from easily chipping in the setting. A normal culet should be about 1% - 2% of the overall diameter.

 

Diamond Color

Diamond Color

Diamonds graded D through F are naturally the most valuable and desirable because of their rarity. Such diamonds are a treat for the eyes of anyone. But you can still obtain very attractive diamonds that are graded slightly less than colorless. And diamonds graded G through virtually no color that is visible to the untrained eye.

2. Color

The nest quality as per color grading is totally colorless, which is graded as "D" color diamond across the globe, meaning it is absolutely free from any color. The next grade has a very slight trace of color, which can be observed by any expert diamond valuer/grading laboratory. However when studded in jewellery these very light colored diamonds do not show any color or it is not possible to make out color shades. These are graded as E color or F color diamonds.

Most diamonds used as gemstones are basically transparent with little tint, or white diamonds. The most common impurity, nitrogen, replaces a small proportion of carbon atoms in a diamond's structure and causes a yellowish to brownish tint. This effect is present in almost all white diamonds; in only the rarest diamonds is the coloration from this effect undetectable. The GIA has universally recognized, superseding several older systems. The GIA system uses a benchmark set of natural diamonds of known color grade, along with standardized and carefully controlled lighting conditions. Diamonds with higher color grades are rarer, in higher demand, and therefore more expensive, than lower color grades. Oddly enough, diamonds graded Z are also rare, and the bright yellow color is also highly valued. Diamonds graded D-F are considered "colorless", G-J are considered "near-colorless", K-M are "slightly colored". N-Y usually appear light yellow or brown.

Diamonds graded D through F are naturally the most valuable and desirable because of their rarity. Such diamonds are a treat for the eyes of anyone. But you can still obtain very attractive diamonds that are graded slightly less than colorless. And diamonds graded G through virtually no color that is visible to the untrained eye.

Diamond Clarity

FF
Flawless: No internal or external flaws. Extremely rare.


IF
Internally Flawless: no internal flaws, but some surface flaws. Very rare.


VVS1-VVS2VVS1-VVS2
Very Very Slightly Included (two grades). Minute inclusions very difficult to detect under 10x magnification by a trained gemologist.

VS1-VS2VS1-VS2
Very Slightly Included (two grades). Minute inclusions seen only with difficulty under 10x magnification.

SI1-SI2SI1-SI2
Slightly Included (two grades). Minute inclusions more easily detected under 10x magnification.

I1-I2-I3I1-I2-I3
Included (three grades). Inclusion visible under 10x magnification AS WELL AS the human eye. We do not recommend buying diamonds in any of these grades.

3. Clarity

Clarity is a measure of internal defects of a diamond called inclusions. Inclusions may be crystals of a foreign material or another diamond crystal, or structural imperfections such as tiny cracks that can appear whitish or cloudy. The number, size, color, relative location, orientation, and visibility of and other organizations have developed systems to grade clarity, which are based on those inclusions which are visible to a trained professional when a diamond is viewed under 10x magnification.

Diamond become increasing rare when considering higher clarity gradings. Only about 20% of all diamonds mined have a clarity rating high enough for the diamond to be considered appropriate portion contains one or more visible inclusions. Those that do not have a visible inclusion are known as "eye-clean" and are preferred by most buyers, although visible inclusions can sometimes be hidden under the setting in a piece of jewelry.

Most inclusions present in gem-quality diamonds do not affect the diamonds' performance or structural integrity. When set in jewelry, it may also be possible to hide certain inclusion behind mounting hardware such as prongs in a way that renders the defect invisible. However, large clouds can affect a diamond's ability to transmit and scatter light. Large cracks close to or break-ing the surface may increase the likelihood of a fracture.

Diamonds are graded by the major societies on a scale ranging from awless to imperfect.

Diamond Carat

4. Carat

The carat weight measured the mass of a diamond. One carat is defined as 200 milligrams (about 0.007 once avoirdupois). The point unit - equal to one one - hundredth of a carat (0.01 carat, or 2mg) -- is commonly used for diamond of less than one carat. All else being-equal, the price per carat increases with carat weight, since larger diamonds are both rarer and more desirable for use as gemstones.

The price per carat does not increase linearly with increasing size. Instead, there are sharp jumps around milestone carat weights, as demand is much higher for diamonds weighing just more than because of differences in demand.

A weekly diamond price list, the Rapaport Diamond Report is published by Martin Rapaport, CEO of Rapaport Group of New York, for different diamond cuts, clarity and weights. It is currently considered the de-facto retail price baseline. Jewelers often trade diamonds at negotiated discountd off the Rapaport price (e.g., "R -3%").

In the wholesale trade of gem diamonds, carat is often used in denominating lots of diamonds for sale. For example, a buyer may place an order for 100 carats (20 g) of 0.5 carats (100 mg), D-F VS2 - SI1, excellent cut diaminds, indicating a wish to purchase 200 diamonds (100 carats (20 g) total mass) of approximate characteristics. Because of this, diamond price (particularly among wholesale and othes industry professionals) are ofter quoted per carat, rather than per stone.

Total carat weight (t.c.w) is a phrase use to describe the total mass of diamonds or other gemstone in a piece of jewelry, when more than one gemstone is used. Diamond solitaire earrings, for example, are usually quoted in t.c.w. when placed for sale, indicating the mass of the diamonds in both earrings and not each individual diamond. T.c.w. is also widely used for diamond necklaces, bracelets and other similar jewelry pieces.

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