Diamonds are hundreds of millions of years old. Their formation begins deep in the earth’s core where carbon-bearing materials
are crystallized under tremendous heat and pressure and brought to the surface after deep volcanic eruptions. A diamond is chemically identical to carbon but not physically.
Diamonds have an isometric cubic structure, like a honeycomb. It is this physical difference that miraculously allows a diamond to possess three extraordinary qualities: Firstly, due to its unique physical structure, diamonds hold breathtaking optical characteristics. When cut into proper proportions, it is able to gather and reflect light in a beautiful shower of fire and brilliance.
Secondly, diamonds are the purest of all the world’s gemstones. They are composed of more than 99.95% pure carbon, making it
the only mineral to be composed of a single element.
Thirdly, it is the hardest transparent substance known to man. It is these qualities that have made the diamond the world’s most enduring, endearing, mystical, spiritual and most romanticized precious stones.
Carat is the standard unit of measurement for diamonds. The probable origin of this measure dates back to antiquity where the seed of the carob tree was used as a unit of measure in gem trading. The word carat comes from “kuara”, which stands for the seed of the African carob tree. The reason for using this seed as a unit of measurement was its remarkable consistency of weight. The metric weight of a carat equals 0.2 grams. A carat may be divided into 100 “points” – so a 0.75ct diamond is called a 75-point diamond. It seems obvious that the heavier a diamond is, the more valuable it will be. However, as cut, clarity and colour also help to determine value, it is possible that a smaller stone can be more valuable than a larger diamond with inferior characteristics. For this reason, stones of equal weight can vary a great deal in price.
But why should a diamond of twice the weight cost more than twice the price with similar clarity and colour? The simple reason is that large diamond sizes are becoming increasingly rare. In other words, the scarcer a diamond is, the higher its worth. So a larger diamond does not just cost more. It also costs more per carat.
Clarity refers to the presence, quantity, size, position, nature, and colour of internal features such as breaks or foreign bodies, called inclusions. Clarity also refers to external imperfections such as scratches, called blemishes. Both blemishes and inclusions lower the clarity grade of a diamond and have an adverse affect on its value; the more inclusions there are the less effective a diamond is in reflecting light. Like colour, clarity is graded by a very specific international standard:
Free from inclusions and blemishes. Shows no inclusions or blemishes of any sort under 10x magnification.
Free from inclusions. May have slight blemishes under 10x magnification. VVS1, VVS2 Very Very Slightly Included Contains minute inclusions difficult to see under 10x magnification.
Very Slightly Included
Contains minute inclusions (small crystals, clouds or feathers) not visible to naked eye and hard to detect with 10x magnification.
Contains small inclusions (clouds, included crystals, knots, cavities and feathers) not visible to the naked eye but noticeable under 10x magnification.
I1, I2, I3
Contains inclusions and blemishes (possibly large included crystals or large feathers) visible to the naked eye. May affect transparency and brilliance.
Colour is a very important characteristic of a diamond. Usually, the more colourless the diamond, the greater its rarity and value. To the untrained eye, most diamonds appear colourless, but in reality they have very subtle shades of colour, often traces of yellow, brown or gray. When diamonds are formed under extreme temperatures and pressure, the carbon crystallizes with other elements. It is traces of these elements that affect the colour of a diamond. Intense colours of yellow, pink, blue, green and red can also occur in diamonds, which are very rare and expensive in value.Diamonds are graded on a colour scale using letters ranging from D (colourless or white) through to Z (light yellow).
Cut refers to the proportions and angles that,a skilled craftsman creates when cutting a rough diamond into a polished diamond. The brilliance, fire, and scintillation that make diamonds breathtaking largely depends on the precision with which a diamond is cut to perfect proportions. In order to maximize this effect, a diamond cutter must place each of the stone’s facets and angles in exact geometric relation to one another. Only by doing so will a well-cut diamond reflect light internally from one mirror-like facet to another and disperse it through the top of the stone. 6 Cuts that are too deep or too shallow lose or leak light through the side or bottom, affecting the diamond’s brilliance.
1. Brilliant Cut
The most classic and most popular of all cuts is the Round Brilliant Cut, which consists of fifty-eight facets.
The most important elements we consider when analyzing a diamond’s proportions are:
When we discuss the table size of a diamond we always consider it relative to the size of the stone, which is expressed as a percentage of the girdle diameter.
When purchasing a Round Brilliant Cut diamond the table size should lie between 55% and 65%. Anything less than or more
than this will reduce the brilliance of the stone.
The crown angle is the angle where the bezel facets and girdle plane meet. Most diamonds have crown angles between 30° and 35°. If they are shallower than 30° there is a noticeable loss of fire.
Brilliance in a diamond is mainly determined by the pavilion depth percentage, which is the distance from the girdle plane to the
culet expressed as a percentage of the girdle diameter. Diamonds with shallow pavilions look dull and flat, and create the impression of a fish-eye in the diamond, which is in fact the reflection of the girdle in the table of the diamond. Diamonds with deeper pavilions, face up, look dark and are called “nailheads”, because they resemble the head of a shiny nail. When purchasing a Round Brilliant Cut diamond the pavilion depth should lie between 40% and 44%. Anything less or more than this will reduce the brilliance of the stone.
The better the symmetry of a diamond the more the display of brilliance, fire and scintillation. Other “Brilliant” Cuts are called “Fancy” Cuts and they include:
2. Step Cut
These cuts give a colder brilliance and play with the transparency of the stone. They include:
3. Mixed Cut
These cuts have characteristics of both Brilliant and Step Cuts. They include:
4. Cabochon Cut
Stones found in this cut have smooth or buffed surface.