The Four C’s

A diamond’s weight is measured in carats, the easiest of the four C’s to determine. Each carat is divided into 100 parts called points. A half carat diamond is equal to 50 points or 0.50 carats. Carat weight does not refer to the size of a stone. A one carat ruby will not have the same geometric measurements as a one carat diamond. Rubies weigh more than diamonds. Two diamonds of equal size can differ in value due to its colour, clarity, and cut. The price per carat can increase exponentially as diamonds increase in size. Two diamonds, weighing 0.50 carats and the other weighing 1.00 carat, with equal cut, colour, and clarity will have significant cost differences.

Cut, the arrangement of a diamond’s facets, is one of the most important of all characteristics, and among the hardest to judge. A diamond’s shape is not to be confused with its cut. The proportions of a stone, symmetry, polish, and precision of faceting determine how much of the diamond’s potential fire and beauty may be released, its perceived size and even, its apparent colour. Percentages for depth, height and angles are also important. Light should enter and exit a diamond through the top facets. A cut that is too shallow or too deep reflects it through the bottom facets, and lets the light “leak” out of the bottom or side of the stone.

All other factors being equal, a poorly cut diamond can value far less than a well cut or ideal cut stone. Diamond cutters are paid to retain the maximum weight from rough stones. Extremely poor cut diamonds such as long, fat, or deep stones tend to result in a higher yield (less waste) from the rough while a better made diamond “wastes” more of the rough. This is why better cut diamonds and near ideal cut stones command a premium.

Ideal Cut: Ideal cut diamonds follow strict mathematical proportions and release the maximum amount of light. All light that enters an ideal cut diamond is refracted through the top of the diamond to produce the maximum brilliance and fire. Only round diamonds can be graded as ideal cuts because symmetry is required for maximum light reflection.

Shallow Cut: When cut too shallow, a diamond loses light out of the bottom or sides, and appears lifeless to the eye. Many diamonds are cut to increase carat weight in order to produce a larger diameter when cutting from the original rough. Although you may end up with a diamond that appears larger, your sacrifice will be brilliance and fire.

Deep Cut: When cut too deep, a diamond loses light out of the bottom, leaving the centre of the diamond dark in appearance.

Each letter marks a different colour grade. Increased shadings of yellow reduce the value of a diamond, but they do not necessarily reduce its beauty. Well cut diamonds can disguise colouration through their fire and brilliance. The best way to judge a diamond’s colour is to look at it on a white background. The ideal colour for a diamond is no colour.

D – F: Colourless: the most valuable and desirable colour grade because the maximum amount of light passes through this colour range.
G – J: Near Colourless: these stones appear colourless to the untrained eye and can appear colourless after being mounted (especially in yellow gold).
K – M: Faint Yellow: slightly tinted with yellow colour to the untrained eye, but still considered desirable for affordable pieces of jewellery.
N – R: Very Light Yellow: visible yellow tint to the untrained eye.
S – Z: Light Yellow: highly noticeable yellow tint to the untrained eye.

A diamond’s clarity is determined by the number, location, and intensity of inclusions such as crystals, clouds, or feathers it contains. Inclusions, naturally occurring imperfections, can be viewed under a 10 times magnification. The fewer the inclusions, the more valuable the stone. A well cut diamond can minimise the appearance of inclusions.

F:  Flawless: contain no internal or external inclusions under 10 times magnification
IF: Internally Flawless: contain insignificant surface imperfections, but no internal inclusions
VVS1-VVS2: Very, Very Slightly Included: inclusions are extremely difficult to find under 10 times magnification.
VS1-VS2: Very Slightly Included: inclusions are difficult to see under 10 times magnification and appear 100% clean to the naked eye.
SI1-SI2: Slightly Included: noticeable inclusions that are easily found under a 10 times magnification.
I1-I2: Included: contain obvious inclusions under 10 times magnification and can be seen with an unaided eye.
I3: Included: contain noticeable internal and external inclusions which are easily seen by an untrained eye.