4cs

FUNDAMENTAL'S OF 4C's

Cut

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

The GIA Diamond 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. 

The major components, from top to bottom, are the crown, girdle and pavilion. A round brilliant cut diamond has 57 or 58 facets, the 58th being a tiny flat facet at the bottom of the pavilion that’s 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. 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.

Clarity

Diamonds are 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 International Diamond Grading System™, 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. Most jewellers have never even seen one.

The GIA 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 or relief, 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.

Carat

Diamond colour is all about what you can’t see. Diamonds are valued by how closely they approach colourlessness – 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.

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.

Colour

Diamonds and other gemstones are weighed in metric carats: one carat is equal to 0.2 grams, about the same weight as a paperclip. (Don’t confuse carat with karat, as in “18K gold,” which refers to gold purity.)

Just as a dollar 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 Four C’s: clarity, color and cut. The majority of diamonds used in fine jewellery weigh one carat or less.