Diamond Education - Know more about Diamonds

The 4 ‘C’s of Diamonds: Cut, Colour, Clarity & Carat Weight

Cut

The Cut determines

• The diamond’s brilliance and beauty

• The diamond’s ability to reflect light

• The diamond’s proportions, symmetry and finish

A well-cut diamond appears brilliant and fiery, while a badly cut diamond looks dull and lifeless, despite having a good colour and clarity grade.

The Cut is a set of measurements based on how light travels within the diamond and exits from the top. The Cut is the only “man-made” C of the 4C’s.

Do not confuse Cut with Shape. Cut refers to how well the diamond has been designed and proportioned by the cutter. Shape refers to the general silhouette or outline of the diamond.

An ideally proportioned diamond is cut according to scientific formulae calculated to maximise brilliance. In such diamonds, light that enters the stone from the top will bounce about within the diamond to create multiple reflections, which exit the stone from the top, causing the diamond’s glitter.  

Diamonds that are cut too deep or too shallow lose or leak light through the side or bottom. The result is less brilliance, and ultimately less value for the diamond.

The most important proportion is the ratio between the depth and the diameter of the diamond. The ideal ratio is 58.5%, but slight deviations are acceptable. The ratio between the height of the crown and that of the pavilion is also important. Please remember that this ideal ratio applies only to the Round Brilliant shaped diamonds. Gemologists differ on the ideal depth percentages to be followed in the other fancy shapes, and therefore, no ratios have been set as ideal for any of the other shapes.

Other factors that count are length of the pavilion facets, size and shape of the various crown facets, size of the table and the culet.

Polish and Symmetry

Symmetry

• Dramatically amplifies brilliance of a well-proportioned diamond

• Is crucial in diamonds of very high clarity grades

Polishing

• Gives the diamond its final appearance

• Is crucial to its brilliance

• Ensures smooth passage of light through the diamond

Rating of the Cut

The Gemmological Institute of America (GIA), the authority in diamond certification, grades diamond cuts as Excellent, Very Good, Good, Fair, or Poor.

The GIA determines cut grades on the basis of:

• Brightness, Fire, and Scintillation

• Weight Ratio and Durability

• Polish and Symmetry

What is the best cut grade

• If you are looking for the most exceptional diamonds that can attain the highest gemological standards, do not look beyond CaratLane Signature Collection. These diamonds are cut to the exact proportions to get the maximum brilliance. They have the best polish and symmetry grades available for round diamonds, and our signature fancy shapes have either ‘excellent’ or ‘very good’ polish and symmetry grades.

• If you are looking for a round brilliant diamond that gives the best value for your money, choose a diamond with a cut grade of ‘good’ or ‘very good’, and polish and symmetry grades of ‘very good’ or ‘good’.

• If the diamond you have selected has an ideal- or very-good cut with very good or good polish and symmetry, you can buy lower grades of color and clarity — look for a diamond with G or H color and SI1 or SI2 clarity.

Colour

The ideal diamond is completely colourless, and the most expensive. However, most diamonds which appear colourless actually have slight tones of yellow or brown.

The Gemmological Institute of America (GIA), the authority in diamond certification, grades colour alphabetically from D (totally colourless) to Z (heavily tinted).

Please note the differences in grades are subtle, and mostly not visible to the naked eye. A diamond with a visible tint such as K and above can still be beautiful if it has good clarity and cut. Only diamonds graded N onwards have a tint visible to the naked eye. From S onwards, the tint grows more intense.

Natural colour diamonds come in all shades and colours of the rainbow. The most popular colours are combinations of pink, blue, brown, yellow, orange, green and red. Yellow is the most common naturally occurring fancy colour, while red, blue and green diamonds are very rare.

Clarity

Clarity defines:

• Defines the extent of flaws in the stone

• Determines the diamond's ability to allow free passage of light without obstruction or absorption

• Determines the value of the diamond

Flaws in diamonds are of two types:

Inclusions are

• A diamond’s natural imperfections

• Permanent tiny spots found within the diamond, mostly invisible to the naked eye

• A diamond’s fingerprints, which contribute to its identification

• Can be white, black, colourless, red or green

Inclusions are not flaws in the strict sense of the term. They are nature's signature on a diamond, akin to birthmarks. Like fingerprints, no two diamonds are identical. Your diamond is identified by inclusions if it is ever lost or stolen.

A diamond's clarity rating is determined by the number, size, type and location of inclusions under 10 x magnifications. The Gemmological Institute of America (GIA), the authority in diamond certification, has developed a professional scale to determine different clarity grades.

• A diamond need not be completely clean to be highly attractive

• Most diamonds bought have varying amounts of internal/external flaws

• Please note that less than 1% of diamonds mined are flawless, and hence the most expensive

Some inclusions affect a diamond's clarity, making it less brilliant, as they interfere with the light reflected. Others can make a gemstone vulnerable to shattering. You don’t have to worry about diamond inclusions as long as they do not affect the stone's strength or seriously impact its appearance.

Diamonds with VVS and VS grades are very good choices. Diamonds with lower clarity grades (S1, S2, and I1), but that are still eye-clean—that is, with no visible inclusions, are more affordable. They are indistinguishable from a higher-clarity diamond when viewed with the naked eye.

The GIA grading of clarity of diamonds translates as follows:

• FL:  Completely flawless

• IF:  Internally flawless; external flaws present can be removed by further polishing

• VVS1 - VVS2:  Only an expert can detect flaws with a 10X microscope. By definition, if an expert can see a flaw from the top of the diamond, it is a VVS2.  If the expert can only detect flaws while viewing the bottom of the stone, then it is a VVS1

• VS1 - VS2:  You can see flaws with a 10X microscope, but it is not obvious (takes more than about 10 seconds to identify the flaw)

• SI1 - SI2:  You can see flaws readily with a 10X microscope

• I1 - I3:  You can see flaws with the naked eye.  Eminently avoidable.

Blemishes

Blemishes are imperfections on a diamond’s exterior surface. Many exterior flaws— nicks, pits, trigons, and polishing lines—are a result of the cutting and polishing process. Depending on their location and size, most blemishes can be polished away, or the diamond can be re-cut to eliminate them.

Surface blemishes can affect a diamond’s clarity and value, but many blemishes have little or no impact on a diamond's appearance.

Carat Weight

Size is the most visible factor that determines the value of a diamond. The price of a diamond rises exponentially according to its size.

By definition, 1 carat is 200 milligrams.  Since most diamonds sold in the market weigh less than 1 carat, the carat is usually subdivided into "points."  There are 100 points in 1 carat, so that a diamond weighing 3/4 carat would be a "75 point diamond."

1 carat = 200 milligrams = 100 points

Please note that Carat weight is not a factor which denotes diamond quality. It merely denotes the size of a diamond, by its weight.

Diamonds of 0.5 - 0.75 carat are very popular for their combination of size and value.

Large diamonds are rarer to find in mines than small ones, which makes large diamonds much more valuable.