Understanding Diamonds

What are diamonds and where do they come from?

Of all the gemstones a diamond is the simplest in composition - it is pure crystalline carbon. Formed billions of years ago deep within the earth's mantle under conditions of extreme temperature and pressure, diamonds are the hardest natural substance known to man.
Their occurrence on or near the earth's surface stems from the eruption of the volcanic magma in which they crystallised. This upward thrust of molten rock then broke the earth's surface to cool in the form of 'kimberlite' and 'lamproite' pipes of diamond-bearing rock. It is in these pipes that most diamonds are found today.
In terms of world production of diamonds, there has been an historical shift in the relative importance of different countries. Prior to their discovery in South Africa in 1866, the main sources were India and Brazil.
Today the story is more complex. The leading producers in value terms are Botswana, Russia and South Africa, whilst Australia leads the way in volume, producing a far greater proportion of diamonds suitable only for industrial uses, being too low grade for inclusion in jewellery.

Romantic history of diamonds

The ancient word for diamond was 'adamant', coming from the Greek 'Adamas', meaning unconquerable. Until the 15th century diamonds were worn mainly by kings as a symbol of strength, courage and invincibility.
But the Greeks also believed that the fire within a diamond reflected the constant flame of love.
The stone's association with romance and legend has grown over the centuries. In 1477 when Archduke Maximillian of Austria gave a diamond ring to Mary of Burgundy, the tradition of diamond engagement rings was born.

Unique properties of diamond:

Diamonds possess unique physical and optical properties and it is from these that their beauty and desirability stems. It should be emphasised that in their naturally occurring uncut state, a handful of diamonds might resemble a handful of dull gravel. The role of the cutter in releasing a diamond's beauty is crucial and more detail on this can be found under our section on Cut.

Physical properties:

It is widely known that diamond is the hardest naturally occurring substance known to man. Its hardness stems from the extremely compact way in which the carbon atoms bond to create its crystal structure. This allows a diamond to achieve a higher level of polish which gives it greater lustre than any other gemstone. It also allows it to withstand abrasion and retain its polish.
The physical resilience of the stone also makes it invaluable for numerous industrial purposes such as drilling. Its hardness combined with excellent thermal conductivity enable it to cut ruthlessly whilst dissipating heat effectively without overheating.
Optical properties:
When we describe the appearance of diamonds, we often refer to the high levels of 'brilliance' and 'fire' which they display. These are terms used to describe the stunning effect of reflected light accompanied by a play of spectral colours that we see when a well-cut diamond catches the light.
The reason for these fabulous light gymnastics stems from the diamond's high refractive index - when light travels from air into a denser medium, it slows down, to a large degree in the case of diamonds, from 300,000 km/second to 124,000 km/second. The spectral colours, which constitute white light, all have different wavelengths, which are slowed down by differing degrees when they enter the diamond. This results in their separation, and when the light exits the stone in an array of colours, this effect is known as 'dispersion'.

The 4Cs

The 4Cs - cut, colour, clarity and carat weight - are the characteristics that determine a diamond's rarity and value. They are the four basic industry-accepted grading criteria which present the key to explaining why two diamonds of equal size may not be of equal value. A basic understanding of each characteristic is therefore important for making an informed purchase decision.

Which one is most important?

The beauty and value of a diamond are dependent on the combination of these factors. There is no straightforward answer to this question, as it comes down to a matter of personal taste. For many people size is the most important consideration and so they will buy the largest diamond they can afford. Others may feel more strongly about quality, and so are prepared to sacrifice some size so as to afford a stone of exceptional colour and clarity.

Cut

Of all the 4Cs this is the one most directly influenced by man. The other three are dictated by nature. The Cut of a diamond is graded according to its geometric proportions, as these are what determine how light will behave when it enters and exits a stone.