Superb and Rare Fancy Vivid Blue Diamond 罕有4.50克拉 艷彩藍色鑽石

Fancy Vivid Blue Diamonds

Only 0.3% of all diamonds display a colour that is predominantly blue. Of this only a very small subsection qualifies as Fancy Vivid Blue. In a study comprising over 462 blue diamonds, the Gemmoligical Institute of America (GIA) graded merely 1% as Fancy Vivid Blue. The GIA was able to establish that blue diamonds are formed far deeper in the Earth’s mantle than any other diamonds. Furthermore, the world-renowned laboratory also discovered an inherent link between blue diamonds and the oceanic waters.

Boron and Oceanic Crustal Subduction

The colour of blue diamonds is caused by the trace element boron. Boron is a chemical element that is concentrated in rocks and sediments near the Earth’s surface. When these crustal rocks weather and decompose, boron is filtered into rivers where it is delivered as dissolved chemical elements into the ocean. In mantle rocks, however, the concentration of boron is very low.

Recent scientific studies suggest that boron, incorporated in clays and other minerals in the oceanic crust, is carried down into the mantle along with hydrous minerals by a conveyor-like-process which is called oceanic crustal subduction by geologists. In the mantle, these crustal minerals break down and release a boron-rich fluid that triggers diamond formation.

Formation

It is possible for geologists to age-date the formation of rough diamond crystals based on tiny amounts of radioactive mineral inclusions which get trapped in the growing crystals. It is now known that diamond formation began as much as 3.5 billion years ago, and the resulting crystals then remained deep in the earth for millions of years, before being emplaced near the earth’s surface in more recent geological times.

Most blue diamonds contain boron and little to no nitrogen, they display an irregular crystal lattice and can sometimes occur in large sizes. These features suggest formation under different geologic conditions compared to the majority of colourless diamonds. Blue diamonds can also contain mineral inclusions which allow geologists to deduce information on the depth and host rock during the diamond’s formation. The minerals encountered within these inclusions are only found together in environments exposed to high pressure, extremely deep inside the Earth’s mantle.

These mineral inclusions allow scientists to conclude that blue diamonds formed at a depth of 400 to 600 kilometers within the Earth’s mantle. In contrast, the majority of near-colourless diamonds were created between 150 and 200 kilometers below the Earth’s surface and resided there for millions of years before volcanic eruptions emplaced them near the Earth’s surface. Therefore, blue diamonds are formed much deeper within the Earth’s mantle than the vast majority of other diamonds.