Expertise

There is no other gemstone quite like a diamond

The fact that it forms at all is a miracle of nature. Diamonds are found in the most remote places on earth and take the extraction of over one tonne of rock to recover less than half a carat of rough diamond. This, coupled with the fact that only thirty percent of recovered rough diamonds are gem quality, makes diamond one of the rarest and most desirable gemstones in the world.

Diamonds spend billions of years forming under extreme temperature and pressure before being brought to the earth’s crust which makes them a testament of strength and endurance.

Every diamond is unique, yet all diamonds share certain features and characteristics that allow us to compare and evaluate them. These are known as the 4Cs: Colour, Clarity, Cut, Carat

Colour

Diamond colour is all about what you can’t see. Diamonds are valued by how little colour is present – the less colour, the higher their value. (The exception to this is fancy colour diamonds, such as pinks and blues, which lie outside this colour range.) Most diamonds found in jewellery stores run from colourless to near-colourless, with slight hints of yellow or brown.

GIA’s colour-grading scale for diamonds is the industry standard. The scale begins with the letter D, representing colourless, and continues with increasing presence of colour to the letter Z, or light yellow or brown. Each letter grade has a clearly defined range of colour appearance. 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 as to be invisible to the untrained eye. But these slight differences make a very big difference in diamond quality and price.

Clarity

Because diamonds formed deep within the earth, under extreme heat and pressure, they often contain unique birthmarks, either internal (inclusions) or external (blemishes).

Diamond clarity refers to the absence of these inclusions and blemishes. Diamonds without these birthmarks are rare, and rarity affects a diamond’s value. Using the GIA’s clarity grading scale, diamonds are assigned a clarity grade that ranges from flawless (FL) to diamonds with obvious inclusions (I3).

Every diamond is unique. None is absolutely perfect under 10× magnification, though some come close. Known as Flawless diamonds, these are exceptionally rare.

The GIA’s clarity scale contains 11 grades, with most diamonds falling into the VS (very slightly included) or SI (slightly included) categories. In determining a clarity grade, the GIA system considers the size, nature, position, colour, and quantity of clarity characteristics visible under 10× magnification.

Flawless (FL) - No inclusions or blemishes are visible to a skilled grader using 10× magnification

Internally Flawless (IF) - No inclusions and only blemishes are visible to a skilled grader using 10× magnification

Very, Very Slightly Included (VVS1 and VVS2) - Inclusions are difficult for a skilled grader to see under 10× magnification

Very Slightly Included (VS1 and VS2) - Inclusions are minor and range from difficult to somewhat easy for a skilled grader to see under 10x magnification

Slightly Included (SI1 and SI2) - Inclusions are noticeable to a skilled grader under 10x magnification

Included (I1, I2, and I3) - Inclusions are obvious under 10× magnification and may affect transparency and brilliance

Cut

Cut quality is the factor that fuels a diamond’s fire, sparkle and brilliance. The allure and beauty of a particular diamond depends more on cut quality than anything else.

The GIA’s cut-grading system for standard round brilliants in the D-to-Z colour range is based on the assessment of seven components. The first three — brightness (the total light reflected from a diamond), fire (the dispersion of light into the colours of the spectrum), and scintillation (the pattern of light and dark areas and the flashes of light, or sparkle, when a diamond is moved) — are appearance-based aspects. The remaining four — weight ratio, durability, polish, and symmetry — are related to a diamond's design and craftsmanship.

In GIA’s system, each component is assessed individually, taking into account the relative importance of that component in the overall cut quality of the diamond. Each cut grade, based on a relative scale from Excellent to Poor, represents a range of proportion sets and face-up appearances. There are many different proportion sets that produce attractive diamonds.

For example, look at a side view of the standard round brilliant. The major components, from top to bottom, are the crown, girdle and pavilion. A round brilliant cut diamond has 57 facets. The proportions of a diamond refer to the relationships between table size, crown angle and pavilion depth. It is important to note that a wide range of proportion combinations are possible, and these ultimately affect the stone’s interaction with light and how attractive the diamond is to the person viewing it.

While it is important to consider many components when assessing the overall cut appearance and quality of round brilliant diamonds, an individual's preferences also play a role. Because each cut grade represents a wide range of proportion sets, individuals have the freedom to choose which particular appearance they prefer within the grade range.

Carat

Diamonds and other gemstones are weighed in metric carats: one carat is equal to 0.2 grams.

Just as one pound is divided into 100 pennies, a carat is divided into 100 points. For example, a 50-point diamond weighs 0.50 carats. But two diamonds of equal weight can have very different values depending on the other members of the 4Cs.

Because even a fraction of a carat can make a considerable difference in cost, precision is crucial. In the diamond industry, weight is often measured to the hundred thousandths of a carat, and rounded to a hundredth of a carat. Diamond weights greater than one carat are expressed in carats and decimals for instance, 1.08 ct.




The 4Cs provide a way to objectively compare and evaluate diamonds. However, numbers and grades alone cannot describe a diamonds mysterious and captivating beauty – for that you will have to visit us at S.P. Green and see one for yourself.


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