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How did the 4Cs of Diamond Quality Come to Be?

Because diamonds are so valuable, it’s essential for industry professionals to have a universal grading system when comparing diamond quality. In the mid-twentieth century, GIA developed the International Diamond Grading System™ and the 4Cs as a way to objectively compare and evaluate diamonds.

The Four Cs of diamond quality will give you a multitude of information about a diamond’s characteristics and value, but they can’t begin to describe one elusive quality – beauty. To do that, you’ll need to experience the diamond with your own eyes.

Carat weight is the most intuitive of the 4Cs – you expect a larger diamond to be worth more when assigning diamond values.

Diamonds and other gemstones are weighed using metric carats with one carat weighing about the same as a small paper clip, or 0.2 grams. Just as a dollar is divided into 100 pennies, a carat is divided into 100 points which means that a diamond of 50 points weighs 0.50 carats. But two diamonds of equal weight can have very different values depending on the other three characteristics of a diamond’s 4Cs: clarity, color, and cut. The majority of diamonds used in fine jewellery weigh one carat or less.

The Color of the diamond is all about what you can't see. Diamonds are valued by how closely they approach colourlessness – the less colour, the higher the value. Most diamonds found in jewellery stores run from colourless to near-colourless with slight hints of yellow or brown. The only exceptions are the fancy-colour diamonds that lie outside of this range.

GIA's diamond colour-grading scale is the industry’s most widely accepted grading system. The scale begins with the letter D, representing colourless, and continues, with increasing presence of colour, to the letter Z. Diamonds are colour-graded by comparing them to stones of known colour under controlled lighting and precise viewing conditions.

Many of these colour distinctions are so subtle that they are invisible to the untrained eye. But these slight colour differences make a very big difference in diamond quality and price.

Diamond Clarity refers to the absence of internal inclusions or external blemishes.
Because they are created deep within the earth, most diamonds contain unique birthmarks called inclusions (internal) and blemishes (external). Diamonds with very few birthmarks are rare and, of course, rarity affects a diamond’s value. Using the International Diamond Grading System™, created by GIA, diamonds are given a clarity grade that ranges from flawless (FL) to diamonds with more prominent inclusions (I3).

Every diamond is unique. But none are absolutely perfect even though some come close, even under 10x magnification. Known as flawless diamonds, they are exceptionally rare. Most jewellers have never even see one.

The GIA Clarity Scale contains 11 grades, with most readily available diamonds falling into the VS or SI categories. In determining a clarity grade, GIA considers the size, nature, position, colour or relief, and quantity of clarity characteristics visible under 10x magnification.

 

 

Cut fuels the diamond’s fire, sparkle, and brilliance.

It seems miraculous that the traditional 58 tiny facets in a diamond, each precisely cut and sharply defined, may be only two millimeters in diameter. But without this precision, a diamond wouldn’t be near as beautiful as it is. Without a doubt, the allure of a particular diamond depends more on cut than anything else.

Though extremely difficult to analyze, the cut of a diamond has three attributes: brightness (the total light reflected from a diamond), fire (the dispersion of light into the colours of the spectrum), and scintillation (the light flashes – or sparkle – when a diamond moves).

An understanding of diamond cut begins with the shape of a diamond, with the standard round brilliant dominating the majority of diamond jewelry. All other diamond shapes are known as fancy shapes or fancy cuts and include the marquise, pear, oval, and emerald cuts. Hearts, cushions, triangles, and a variety of other new shapes are also gaining popularity in many forms of diamond jewelry.

As a value factor, though, cut refers to a diamond’s proportions, symmetry, and polish. For example, look at a side view of the standard round brilliant. The major components, from top to bottom, are the crown, the girdle, and the pavilion. A round brilliant cut diamond can have either 57 or 58 facets, the 58th being a tiny flat facet at the bottom of the pavilion, known as the culet. The large, flat facet on the top is the table. The proportions of a diamond refer to the relationships between table size, crown angle, and pavilion depth. A wide range of proportion combinations are possible, and these ultimately affect the stone’s synchronicity with light.

In early 2005, GIA unveiled a diamond cut grading system for standard round brilliants in the D-to-Z color range. This system, the product of more than 15 years of intensive research and testing, assigns an overall diamond cut grade ranging from Excellent to Poor.