Colourless Diamonds
​
Learn all about the Raliegh Goss fine jewellery brand insight into diamonds and why it is so important to do your research before purchasing diamonds. Diamonds were formed by nature at least 990 million years ago and many are billions of years old. Colourless diamonds are graded from the colour D to the colour Z, D being the finest grade. There are four qualities to a diamond, its cut, colour, carat & clarity. These qualities are how a diamond is defined and how it is evaluated in terms of its price. Some companies and collectors will also grade a diamond by its “character” or “charm”. Although this added factor bears no monetary value, it can often be the defining character that can make the decision in its purchase. It is known that collectors and dealers often purchase diamonds on instinct as well as knowledge.
A diamond is a solid form of carbon with a diamond cubic crystal structure. It has the highest hardness and thermal conductivity of any bulk material.
Most natural diamonds have ages between 1 billion and 3.5 billion years and were formed at depths of 150 to 250 kilometres in the Earth's mantle, although a few have come from as deep as 800 kilometres. More recently (hundreds of millions years ago), they were carried to the surface in volcanic eruptions.
The Carat
The carat (ct) is a unit of mass equal to 200mg and is used for measuring gemstones and pearls. The carat or in simpler terms, the weight of a diamond will fluctuate in price depending on its carat weight. The larger the diamond, mostly the more expensive, other factors come into play with the colour, cut and clarity effecting the price.
Colour
Diamonds come naturally in every colour of the rainbow. However, most people are concerned with diamonds in the colourless range, often in retail referred to as “white”. The gemmological institute of America (GIA) rates the body colour in colourless diamonds from D (colourless) to Z (light yellow). D is the finest colourless colour. What retailers and most end clients refer to as a “white diamond” is in fact colourless. White diamonds are extremely rare, they are defined as natural fancy coloured and have a milky opalescent colouring. Although these “white diamonds” are scarce, they currently do not mirror this in their value. This is potentially a gap in the market for investment. For example, a diamond collector, investor or connoisseur will often hold a natural fancy coloured white diamond in his/her collection.
Clarity
A diamonds clarity is determined by the amount and location of flaws and blemishes. A diamond can range from flawless (F) the highest quality, down to included (I), being the lowest. The less included the stone, the more valuable it becomes. >< F-IF-VVS-VS-SI-I. Flawless, internally flawless, very very slightly, very slightly, slightly included and included.
Cut
The cut refers to the manner in which the stone is physically cut, not its shape, rather its proportions. A finer cut has excellent symmetry. Perfect proportions allow light to be reflected and refracted from the top to the bottom of the stone. A deep or shallow cut does not allow such perfect brilliance to be reflected. The better the cut, the more valuable the stone. The value of the stone really depends on what the end client is looking for. For example, a buyer who is not restricted to a “perfect” stone may be more willing to spend his budget on what appears to be a larger stone, a stone that is shallower and has a wider spread, in turn makes it appear to be a larger stone from above. The carat weight can be the same on paper between two stones, however when looked at from above, the more perfect, proportionate stone will naturally have its weight distributed and look smaller to the shallower, wider, less expensive stone. It’s all about where and how the client wishes to spend his money.
Shape
Fluorescence to this day isn’t portrayed enough as an important aspect, the difference of stone that has strong fluorescence and none will affect its price quite dramatically. Though fluorescence may not be visible to the naked eye unless seen under ultraviolet light, it can and does effect the purchase of a stone to dealers, collectors and connoisseurs. Fluorescence is cause by the presence of nitrogen when the diamond is formed over many years and will present itself as glowing blue when put under uv light.
Fluorescence to this day isn’t portrayed enough as an important aspect, the difference of stone that has strong fluorescence and none will affect its price quite dramatically. Though fluorescence may not be visible to the naked eye unless seen under ultraviolet light, it can and does effect the purchase of a stone to dealers, collectors and connoisseurs. Fluorescence is cause by the presence of nitrogen when the diamond is formed over many years and will present itself as glowing blue when put under uv light.
Fluorescence
Reflective Qualities
When a diamond is perfectly cut, light rays from all sides are bent towards the centre of the stone and reflected back through the top in a rainbow blaze of light. If a diamond is not perfectly cut, the light tends to “leak” out through the base or the sides of the diamond. If a diamond is cut too deep, much of the light is reflected to opposite facets at the wrong angle and is lost through the sides. The diamond may appear black in the centre. In a diamond cut too shallow, the light can leak through the bottom.
The reflective qualities differ across the different shapes of diamonds. For example, an emerald and asscher cut with its elegant deco like symmetrical cut doesn’t give the reflective or brilliance qualities a brilliant cut (round) stone does. A radiant cut stone has the same bottom as a brilliant cut stone and therefore has the life and fire that it has. A pear stone can often have what is referred to within the industry as a “ribbon” bang in the middle of it, which can be very unappealing to a dealer or connoisseur for example.
Brilliant cut (round) stones have “hearts & arrows” when viewed under the hearts and arrows viewer, they are accountable for less than 1% of round diamonds in the market. The hearts and arrows appear when perfect symmetry is attained in its cut. This added “character” so to speak is more of a trend rather than an asset that gives is value, even though it only appears when stones are perfectly cut.
Type I and Type II a and b diamonds
Type Ia
The term “Type Ia” defines a diamond class that consists of an element structure in most colourless diamonds. The presence of nitrogen atoms in Type Ia appear in “clusters” within the diamond. The colour of a diamond can alter when the compounded elements effect the diamond, this depending on how these “clusters” are broken down.
Type Ia diamonds have two separate types: Type IaA and Type IaB.
Type IaA diamonds contain pairs of Nitrogen atoms known as A-aggregates. Type IaB diamonds contains even distributed clusters of four Nitrogen atoms called B-aggregates. Due to the fact that neither of these Type diamonds do not absorb any visible light, their colour is not affected. Type Ia seem to mostly be a combination of IaA and Type IaB.
Type Ib
Unlike Type Ia diamonds, Type Ib diamonds nitrogen elements are built in singular form and a far scarcer. They account for around 0.01% of coloured diamonds. Type Ib diamonds tend to absorb both blue and green lights and will often show a more intense hue of colour. The majority of fancy coloured diamonds, particularly those with intense hues are Type Ib.
Type II Diamonds
These diamonds have no nitrogen impurities, they are therefore rarer than Type I diamonds, in many cases they tend to be harder and larger in size.
Type IIa
Desired by investors and collectors, the majority of these Type IIa diamonds were first mined in Golconda, in India. These diamonds rarely contain imperfection, and are known to be famous for their colour. Colourless diamonds of this class that are certified as colour D frequently have a brighter (whiter) quality colour. Natural fancy coloured diamonds that is Type IIa will have very strong hues. They account for a very small percentage of natural diamonds and therefore hold dear value.
Type IIb
​
Similar to Type IIa diamonds, there are no nitrogen atoms within the structure of these diamonds. The addition of Boron is what makes these stones so distinctive. Boron is the element known to be the cause of blue tones within the diamond. Some the most famous diamonds such as the Koh-I-Noor (weighing in at 186 carats) is Type IIa.
