South Africa is known for its rich diamond mining history, particularly in the famous Kimberley region. However, one of the most prized and rare types of diamonds found in South Africa are blue diamonds. These stunning blue gems have captivated collectors and enthusiasts around the world with their unique colour and beauty.
Blue diamonds get their colour from the presence of boron atoms in their crystal structure. The amount of boron in the diamond determines the intensity of the blue colour, with deeper shades fetching higher prices. Blue diamonds are exceptionally rare, with only a small fraction of all diamonds mined worldwide being blue.
The discovery of South Africa’s blue diamonds has added to the country’s reputation as a top diamond producer. The Cullinan mine, located near Pretoria, is one of the primary sources of blue diamonds in South Africa. This world-renowned mine has produced some of the largest and most valuable blue diamonds ever found, including the famous 29.6-carat blue diamond known as the “Heart of Eternity.”
In recent years, research and exploration efforts have focused on uncovering more blue diamonds in South Africa. New technologies and mining techniques have helped diamond miners locate and extract these precious gems from deep within the earth.
The demand for blue diamonds continues to grow, with collectors and investors willing to pay top dollar for these rare and exquisite stones. South Africa’s blue diamonds are valued not only for their beauty but also for their scarcity and uniqueness in the global diamond market.
Blue diamonds are graded using the same criteria as other coloured diamonds, which includes the 4Cs: colour, cut, clarity, and carat weight.
1. Colour: The colour of a blue diamond is the most important factor in determining its grade. The intensity and saturation of the blue hue, as well as any secondary colours present, will determine the diamond’s colour grade. Blue diamonds are graded on a scale from faint to fancy deep blue.
2. Cut: The cut of a blue diamond refers to its proportions, symmetry, and polish. A well-cut diamond will reflect light beautifully and enhance its colour. The cut grade of a blue diamond is based on factors such as brilliance, fire, and scintillation.
3. Clarity: The clarity of a diamond refers to the presence of inclusions or imperfections within the stone. Blue diamonds with fewer inclusions are considered more valuable and will receive a higher clarity grade. The clarity grade of a blue diamond is based on the size, number, and visibility of any imperfections.
4. Carat weight: The carat weight of a blue diamond refers to its size. Larger blue diamonds are rarer and more valuable than smaller ones. Blue diamonds are typically graded based on their carat weight, with larger diamonds receiving higher grades.
In addition to the 4Cs, blue diamonds may also be graded based on their fancy colour, such as the presence of a secondary hue (e.g. greenish blue, grayish blue) and the distribution of colour within the stone. Blue diamonds that exhibit a pure and evenly distributed blue colour are considered more valuable than those with uneven or secondary colours.
Blue diamonds get their unique colour from the presence of trace elements within the diamond’s crystal lattice structure. In the case of blue diamonds, the colour is caused by the presence of boron atoms within the carbon crystal structure. Boron atoms substitute for carbon atoms in the diamond’s structure, and when they absorb certain wavelengths of light, they cause the diamond to appear blue.
The amount of boron present in the diamond, as well as the way the boron atoms are arranged within the crystal lattice, can affect the intensity and shade of blue colour in the diamond. Blue diamonds can range from a pale sky blue to a deep, intense blue, with intermediate shades such as teal and steely blue also found in nature.
The presence of nitrogen and hydrogen impurities in the diamond can also influence the colour of a blue diamond, causing additional undertones or modifying the hue of the blue colour. For example, a blue diamond with a grayish or greenish secondary hue may be influenced by the presence of these impurities.