RARE GEMS

A pure diamond consists of just one single element: carbon. However, the carbon atoms are structured in a unique way, which results in a diamond crystal.

Today’s diamond type classification system divides white diamonds into two main categories — Type I and Type II.

Type I stones contain nitrogen atoms within their crystalline lattice: an impurity which, typically, reduces the diamond’s absence of color or ‘whiteness’, and results in inferior color grade.

Conversely, Type II stones contain no significant amounts of nitrogen and, of these, the very purest are graded Type IIa . Devoid of detectable impurities, they absorb no light, but instead, when cut and polished, refract and reflect it — hence their exceptional white color and brilliance. Understandably quite rare, they account for less than 2% of white diamonds, whereas Type Ia stones make up 98% of all diamonds.

The most chemically pure diamonds known to man, Type IIa diamonds were first identified as originating from India but have since been recovered in some of the major diamond-producing regions of the world.

Famous examples include the 140.64 carat, cushion-shaped Regent diamond — currently part of the collection of The Louvre in Paris; the 105.6 carat Koh-i-Noor diamond — a Golconda stone that is part of the British Crown Jewels, and the 530.20 carat Cullinan I — also known as the Great Star of Africa — discovered at the Premier Mine, in South Africa.

Impurities or defects within the diamond’s atomic structure strongly influence a stone’s color — but they can also combine to create visually astonishing jewels. For instance, Type IIb diamonds contain boron impurities which can result in a stunning natural blue coloration. Incredibly, only a trace amount is required — in a natural Type IIb blue diamond, the boron concentration is approximately 0.5 parts per million.

The most famous example of this is the Hope Diamond, a fancy dark grayish-blue stone of 45.52 carats. Initially owned by King Louis XIV of France, it now resides at The Smithsonian Institute in Washington DC. In recent years the finest and most remarkable blue diamond to come onto the open market is the 14.62 carat, vivid blue Oppenheimer Blue.

Natural radiation emitted by radioactive materials near the crystal during its formation can cause a green color in diamonds. Green diamonds with a uniform coloration are tremendously rare. The best known is the magnificent, 41 carat Dresden Green which resides in The Green Vault, Dresden, Germany. With a documented history dating back to 1726, it’s believed to be the largest, finest naturally green diamond ever known.

Just as rare blue and green diamonds naturally occur, so a dislocation in the diamond structure can cause pink to red colored diamonds. Of these, the most revered are stones graded Fancy Red; a pure, ruby red, with no secondary modifying colors at all, they are exceptionally rare. The most notable red diamond in the world is the Moussaieff Red: a 5.11 carat, Fancy Red, internally flawless, triangular brilliant cut diamond. An extraordinary stone, it remains the largest fancy red natural color diamond ever graded by the GIA.

Despite this, colorless or near-colorless diamonds remain by far the most popular choice for engagement rings — making up more than 85% of sales in recent years. Fortunately, Janus Creations’ bespoke design service affords clients a unique way to pledge their eternity, while still allowing this dazzling stone to take centre stage.