here is something magical about the process of diamond formation. Composed mainly of carbon, they were forged in Earth’s mantle more than 150 kilometres below the surface, under dizzying pressures and extreme temperatures exceeding 1,200 degrees Celsius. They formed long before life appeared. Each natural diamond is a fragment of deep geology, a time capsule estimated to be between one and 3.5 billion years old.
With a rating of ten on the Mohs hardness scale, diamonds are renowned as one of the hardest natural materials and can only be cut and shaped by other diamonds or laser technology.
The language of the 4 Cs
When choosing a natural diamond, gemmologists speak a precise language: that of the 4 Cs, namely Carat, Cut, Colour, Clarity. Carat refers to gem-specific weight measurement; cut reveals light, as a perfect cut transforms a stone into a star; colour assesses the purity of white, from immaculate D to warmer shades; while clarity observes inclusions, traces of time left in each stone.
The word carat originates from the ancient Greek kerátion, in reference to carob seeds. Renowned for their consistent weight (0.2 gram), the latter were used by stone merchants and jewellers in ancient times to weigh gems. This natural unit has survived across the centuries to become the official reference in jewellery, standardised in 1907. One carat is equivalent to 0.2 gram.
The cut has a direct influence on how a diamond reflects colour. A diamond’s beauty stems from collaboration between Nature which created the stone and humankind that revealed its fire. When well cut, a diamond has the ability to break down white light into rainbow splinters.
The colour of a white diamond refers to its lack of colour: the purer and more translucent the stone, the more valuable it is considered. Nonetheless, recent years have seen a growing new fascination with coloured diamonds in pink, blue, intense yellow, green or orange. These stones, known as fancy colour diamonds, owe their hue to extremely rare geological phenomena: traces of nitrogen for yellow, boron for blue and structural deformations in their crystal lattice for pink and red. Their rarity makes them coveted treasures for collectors and major jewellery houses. A recent example is the Pink Star diamond, cut from a 132.5-carat rough diamond mined by De Beers in Africa in 1999. With its exceptional characteristics – “Fancy Vivid Pink” colour, 59.60-carat weight and IF clarity rating – this gem was sold at auction in Hong Kong by Sotheby’s to Chinese jeweller Chow Tai Fook for USD 51.2 million on April 4, 2017.
Clarity refers to the presence or absence of inclusions, growth line and sometimes even tiny fragments of the primitive Earth: natural “flaws” that can be found inside a diamond. Gemmologists call these “the diamond’s fingerprint”. Diamonds with no inclusions (flawless) command a higher price.
These criteria were established and standardised in the 1940s by Robert M. Shipley, founder of the Gemological Institute of America (GIA). They are a kind of universal language spoken by gemmologists, jewellers and collectors around the world. Above and beyond this system, two diamonds with identical characteristics can evoke different emotions. This explains the recent craze for old cut diamonds – Old Mine Cut or Old European Cut – with large facets and a softer fire. They may have less brilliance, yet radiate more life.
A fifth C should be added to the equation: Certificate. No customer today would buy a diamond without a certificate guaranteeing its origin.
A fragment of time
A natural diamond teaches us that beauty can be born in darkness, that pressure can create brilliance, that imperfection can become poetry. Yet their deepest beauty lies in the head-spinning idea that holding a natural diamond in your hands means gazing upon something that existed before us and will outlive us. A fragment of time.
In the following pages, we will explore diamonds from many angles: the work of a diamond dealer and the related responsibility; the historical diamonds that have inspired books and fragrances; the renewed enthusiasm for old-cut diamonds; as well as the nostalgia for a piece of jewellery stolen from the Louvre during last year’s heist and that painters have brought back to life with their brushes.
Natural diamonds are born in the depths of the Earth, not in a laboratory in India or China. They generate an emotion that humankind has learned to reveal and that spans generations, like a light that has been preserved intact.
