When were the first diamonds in history recorded?
In the big inning.
Not sure, but about a month ago astronomers found the first diamond planet, https://www.physicsforums.com/showthread.php?t=524601&highlight=diamond".
Wiki says the following and gives a reference:
Hershey, W. (1940). The Book of Diamonds. New York: Hearthside Press. pp. 22–28. ISBN 1-4179-7715-9.
Which means they are prehistoric in origin and were likely recorded as soon as writing was invented.
In my opinion, the wiki article exagerates what is written in Hershey's book.
Emphasis mine. The meaning of the bold text is different from wiki's "most likely".
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