Sieve Chart

BASIC 4 C'S OF DIAMOND : CARAT , COLOUR , CLARITY , CUT

Carat
A carat is a unit of measurement used to weigh a diamond. One carat is equal to one fifth of a gram (0.2 gram) or 200 mg. One carat is equal to 100 points or 100 cents Carat weight is the most objective of the 4 C's of diamonds as it involves no estimates, comparisons or judgments. Carat weight is directly related to a diamond's value because (all else being equal) larger diamonds are rarer than smaller ones.

Color
The color of a diamond is one of the vital factors influencing the price of diamond. In diamonds, the best color is no color at all. Colorless diamonds are extremely rare, hence making them the most sought after. Contrary to common belief, all diamonds are not truly colorless. They actually come in many different colors - commonly faint yellow or brown.

Colorless diamonds allow the maximum refraction of light thus maximizing brilliance. In comparison Off White diamonds absorb light hence inhibiting brilliance.

There is now an internationally recognized color grading scale which starts at D (colorless), and goes down to Z (light yellow). Each letter grade represents a range of color and is a measure of how noticeable the color is. Colorless diamonds and diamonds that are yellow or yellowish brown are grouped into the categories shown below:

D : Absolutely colorless The highest color grade, which is extremely rare.

E : Colorless Only minute traces of color can be detected by an expert gemmologist.

F : Colorless. Slight color detected by an expert gemmologist, but still considered a "colorless" grade. A high-quality diamond.

G-H : Near-colorless Color noticeable when compared to diamonds of better grades, but these grades offer excellent value.

I-J : Near-colorless Color slightly detectable.

K-M : Noticeable color Light yellow

N-Z : Noticeable color Yellow

D E F G H I J K L M
These grades do not apply to fancy coloured diamonds-they have their own color grading standards.

D, E or F commands the highest prices because of their rarity. Less than 1% of all diamonds are colorless hence they command a premium. For the untrained and unaided eye, it is very difficult to distinguish between D, E or F colors as they are all colorless with miniscule difference in color.

They are then followed by the near-colorless (G- H), followed by ( I- J) with G and H being universally most popular. The spectrum then gets a visible yellow hue from (K-R). Color more intense than (R) is considered fancy.

Shade
Color (shade) of a diamond refers to the amount of yellow or brown tints in a white diamond. Diamonds are given a color grading based on the intensity and prominence of the color seen. Brown diamonds are usually referred as an equivalent color grade.

Diamonds are generally white or they progressively move down in color, in shades of yellow. Occasionally the colors of diamonds are in shades of brown. Diamonds are given a color grading based on the intensity and prominence of the color seen.

Fancy Color
Intensely colored diamonds are known as "fancies" or fancy colored diamonds. Natural Fancy Color Diamonds are rare and can be very expensive. It's said that out of 10,000 normal diamonds one of them would be a fancy color diamond. The most popular fancy color diamond is Yellow. Other colors such as Pink, Blue, purple and Red and can be extremely expensive.

Fancy Coloured Diamond Grading
The color of a fancy colored diamond is measured differently to a normal diamonds. The grading scale is based on the intensity of the color. The GIA fancy color grading scale is: Faint, Very Light, Light, Fancy Light, Fancy, Fancy Intense, Fancy Vivid, Fancy Deep and Fancy Dark.

Clarity
Diamonds are graded for clarity on the basis of internal and external imperfections present.

Flawless Diamonds
Shows no inclusions or blemishes of any sort when viewed under 10x magnification.

IF Diamonds (Internally Flawless)
Shows no inclusion of any sort when viewed under 10x magnification although minor blemishes may be present.

VVS1, VVS2 Diamonds (Very Very Slightly Included)
Inclusions almost impossible to detect with the naked eye and barely detectable under 10x magnification.

VS1, VS2 Diamonds (Very Slight)
Inclusions are minute and normally not visible to the unaided eye but can be detected with little effort under a magnifying loupe.

SI1, SI2 Diamonds (Slightly Included)
Inclusions are visible under 10x magnifications, and may possibly be visible with the naked eye.

I1, I2, I3 Diamonds (Included)
Inclusions are clearly visible to the naked eye.

Clarity Facts

• As the grading decreases the price decreases exponentially. This is because diamonds with better quality (correspondingly with lesser inclusions) are that much rarer.


• Along with the type and number of inclusions, their position also makes an impact on the value and brilliance of a diamond.


• Fortunately diamonds of all clarity grades and prices, including those with eye visible inclusions can look beautiful. It primarily depends on how well they are cut and other factors.

Inclusions
It is a clarity characteristic found within a diamond.

All kinds of internal imperfections formed before or after crystallization of a diamond and all imperfections rising from the surface and developing into the interior of the stone are included under inclusions. They could be pin-points, crystalline objects, feathers, clouds, needle, twinning wisps, internal grainings or even air bubbles trapped inside the diamond.

Inclusions can vary in size, color and relief. Location of the inclusion also has a significant impact on the value and look of a diamond.

Eye Clean
Is a term we use for clarity in diamonds, where the piece when viewed FACE UP looks clean to the unaided /naked/open eye.

Cut
Cut refers to the quality of the proportions, polish and symmetry of a diamond. Of the 4C's, the cut is the aspect most directly influenced by man, whereas the other three C's are influenced by nature.
Hence here the expertise and skills of manufacturing comes into the picture.

The brilliance of a diamond depends a lot on its cut. Whatever the shape, a well-cut diamond always reflects better light. Diamonds with perfect color or clarity also display reduced brilliance if it's cut poorly.

Sub-grades in Cut as a parameter:

• Excellent Cut
• Very Good Cut
• Good Cut
• Fair Cut
• Poor Cut

Proportions (Importance of cut)
Diamonds are cut in many shapes but, it is the precision with which facets are polished on to a diamond, which allows it to capture light and release its brilliance and fire.

• When a diamond is cut to ideal proportions, light is reflected from one facet to another and then dispersed through the top of the stone. This results in a display of brilliance and fire.


• When it is too shallow, light escapes through the pavilion before it can be reflected.


• When it is too deep, some light escapes through the opposite side of the pavilion.

A polished diamond's proportions affect its light performance, which in turn affects its beauty and overall appeal. Diamonds with good proportions optimize the interaction with light, and have good brilliance, fire, and scintillation.

Polish and Symmetry
Polish and symmetry are two other important aspects of the cut. Polish describes the smoothness of the diamond's facets (surface conditions), and symmetry refers to alignment of the facets (the exactness of shape and placement of the facets).

Symmetry
To ensure a diamond has good symmetry, each facet must be consistently sized and positioned opposite its corresponding facet. Symmetry refers to the alignment of one part of the diamond to another. The exactness of a finished diamond shape and the placement of its facet constitute symmetry. With poor symmetry, light can be misdirected as it enters and exits the diamond.

Sub-grades in Symmetry as a parameter:

• Excellent Symmetry
• Very Good Symmetry
• Good Symmetry
• Fair Symmetry
• Poor Symmetry

POLISH
Polishing is the final step in diamond cutting. Ideally a diamond should be free of any visible polish lines, burn marks, scratches or abrasions under 10 x magnifications. The smoother the polish, the more beautiful and brilliant the diamond will appear. Surface facets of a poorly polished diamond appear blurred or are dull in their sparkle.

Flourescence
Another characteristic that does not affect the color grade of a diamond but is worth keeping in mind is fluorescence. This characteristic refers to the diamond's ability to fluoresce under ultraviolet (UV) light. The most common source of UV is a black light. When exposed to UV light, many diamonds will give off a distinctive glowing blue coloration. Although fluorescence may be displayed in various colors, blue is the most common in diamonds. The fluorescence of a diamond is defined by its intensity as either None, Faint, Medium, Strong, or Very Strong.

Milky
It is any hazy or cloudy inclusion in a diamond. These inclusions appear misty white or grey Clouds may be either confined to a small area or may be spread throughout the stone. They usually affect the lustre and brilliance in a diamond.