Where do diamonds form? We are sorry to have to tell you this in a very hard to reach place. They are usually between 150 and 200 kilometers below the surface. But the real treasure lies at great depths. The origin of the most valuable diamonds in the world. They form about 700 km under our feet.
The scientists presented their results at the Goldschmidt geochemistry conference. They believe that this is the origin of pieces like the Smithsonian Institution’s National Museum of Natural History. It is 45.52 carats. Or maybe the 3,100 carat Cullinan, the largest known. It is the heart of the British crown jewels.
Printing makes diamonds
Two diamonds were examined: a large blue 20 carat diamond from a South African mine. And another 124 carat from the Letseng mine in Lesotho.
Diamonds form in the earth’s mantle under high pressure. It is the intermediate layer between the superficial crust and the central core. “Super deep” diamonds are created below the rigid and stable continental plates. Here the cape moves slowly.
Hope is classified as a Type IIb diamond. Contains the element boron, which can cause a blue cast. They are very rare; less than one in a thousand diamonds is classified as this type. The team discovered traces of bridgmanite in the large 20-carat blue diamond from a South African mine. This is important. It is very common in the deep earth, under extreme pressure conditions of the lower mantle, under 660 km, even deeper than most super deep diamonds, “explains Evan Smith. He is a researcher at the GIA (Gemological Institute of America). Bridgmanite does not exist in the upper coat still on the surface.
The journey of the diamonds
The team examined Lesotho’s large diamonds. This large diamond showed the same characteristic bridgmanite mining products. It means that it also formed as a super deep diamond.
“It means the material in these diamonds is going through a remarkable journey,” says Smith. We believe that boron, which gives Hope diamond its distinctive blue color, comes from the bottom of the ocean. From there, plate tectonics pull you hundreds of kilometers into your coat. There is a giant recycling route that takes elements from the surface into the earth. Then it occasionally brings back beautiful diamonds, like passengers in volcanic eruptions. “That explains the origin of the most valuable diamonds in the world.
This fascinating work confirms that the Hope diamond is exceptional and special. One of the rarest objects on earth. You can now start digging.