Largest uncut diamond was a mammoth gem

The largest uncut diamond e’er establish was the Cullinan, discovered inward 1905 almost xviii feet below seat down inward the walls of the Premier diamond mine, almost 24 miles due east of Pretoria, South Africa.
The magnificent rock was weighed, in addition to replicas were made before it was cutting into ix major gems in addition to 96 pocket-sized gems. The largest was 530.4 carats — slightly less than one-quarter pound — in addition to was named the Great Star of Africa. It in addition to its smaller cousin — the 317.3-carat Lesser Star of Africa — are mounted inward the British Crown Jewels.
Before cutting, the rock weighed a whopping 3,106.75 carats — to a greater extent than than 1.3 pounds — only it was non a consummate crystal.
Most diamonds occur equally crystals amongst a feature shape called an octahedron — mean value of 2 four-sided pyramids stuck together at their bottoms. The Cullinan was champaign purpose of such a crystal — it had a curved surface in addition to triangular shaped depressions feature of many diamond crystals — only it was solely almost one-third of an octahedron.
Influenza A virus subtype H5N1 recent article in The Mineralogical Record reconstructed the master copy diamond crystal.
Using a replica of the master copy replica, the missing portions of the crystal were filled inward amongst clay. The results were striking — an octahedron standard almost 4 inches on each side. The master copy crystal powerfulness convey weighed around 8,300 carats, or to a greater extent than than 3.5 pounds.
So where’s the residue of it?
The crystal in all probability was fragmented yesteryear the explosive emplacement of the diamond piping lava, which traveled from 100 miles below seat down at supersonic speed some 1.2 billion years ago. It brought amongst it diamonds that powerfulness convey formed equally long agone equally 3 billion years.
(That’s ane argue the persuasion that diamonds are compressed coal is a myth — coal comes from ancient trees, in addition to at that spot were no trees that far dorsum inward time.)
The Premier Mine has produced quite a publish of other large diamonds, in addition to then some fragments powerfulness convey been recovered during before or after mining in addition to non recognized equally parts of the Cullinan.
Other parts powerfulness convey been transported further upward the pipe, exposed at the surface in addition to carried away yesteryear erosion millennia before mining e’er started. Alternatively, some powerfulness nonetheless prevarication buried miles below the surface in addition to volition never survive recovered.
Or mayhap tomorrow’s Dispatch will acquit the intelligence that some other major fragment of this magnificent rock in conclusion has been found.
Dale Gnidovec is curator of the Orton Geological Museum at Ohio State University.