Blog Earth's Largest Diamonds - and one from Space

[bcmacdonald]

John Pollard published a new blog post.

Planet Earth's "largest diamond ever" history hitlist has been rocked this month, and not just once - but twice - with new (sic) ancient diamonds discovered deep in the mines of Botswana. These new/ancient additions mean that four of the five largest natural rough diamonds ever transported to the surface by Mother Earth have been found...

Continue reading the Original Blog Post.

 

[DejaWiz]

This is a great article!

And this tidbit is enough to boggle the mind:

"They started as diamonds the size of asteroids first, around a kilometer or more in diameter"

 

[oncrutchesrightnow]

Would definitely like to hear more about the Crown Jewels.

 

[kenny]

I've a question for @John Pollard about The Lesedi La Rona.
What was that 2 carats Laurence Graff "cleaned" off.

Snip from the blog:
"Unearthed at the Karowe mine, in northern Botswana, in late 2015, it had a raw weight of 1,111 carats. “Our Light” was purchased at 1,109 carats after cleaning by Laurence Graff for a total of $53 million."

What material was that 2 ct?
Was it part of the diamond that was removed because heavy inclusions made it worthless?
Dirt?

I can't imagine why they would initially report a carat weight of 1,111 if it wasn't finished being "cleaned"?

 

[John Pollard]

I can't imagine why they would initially report a carat weight of 1,111 if it wasn't finished being "cleaned"?

Hi @kenny

It could have been undetected non-diamond detritus upon initial weighing, or some previously damaged portion/s of the crystal may have broken away as it was further cleaned and boiled in preparation for sale.

There's some evidence to suggest it was the latter. A total of five diamonds, all recovered in the same lobe in the same month, were determined by gemologists at GIA (who studied all of them) to have been part of a single larger rough crystal - one that possibly weighed >2,500 carats - but volcanic activity or the mining process broke that larger diamond apart.

To that end, massive diamonds in primary deposits risk damage during the recovery process. Basically, ore passes through LDR (Large Diamond Recovery) mills, where it's pounded, smashed and broken down into manageable pieces. Only very hard minerals make it to the final conveyor belt. That ore is passed in front of banks of X-yay emitters and photomultipliers. Diamond reacts X-rays. When that happens it triggers a response in the photomultipliers, and a a blast of air redirects the diamond-bearing ore into a special collection bin.

This Alrosa video has a good illustration of XRT technology at 1:10. (PSA translation: Crasher = crusher)

 

[John Pollard]

This is a great article!

Thank you, kindly. It was fun to write.

Would definitely like to hear more about the Crown Jewels.

I'm working on a follow up on the Cullinan, specifically, later this month. Stay tuned.

 

[Karl_K]

They are all to small for Mara!!

 

[kenny]

Thanks John.