A Blood Diamond is an incredibly rare Gem and has a 1/25,000,000 chance to be found per second (roughly 1 in 290 days, on average) with Mining Research 1. It can be sold for 2.5mil Coins to the NPC shop.
Mining Scroll[]
Main article: Mining Scrolls
Mining Scrolls can be unlocked with Mining Research 5, which allow you to get 1,200,000 Mining XP from each Blood Diamond (after finding the Blood Diamond Mining Scroll).
Gems 
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 Sapphire •  Emerald •  Ruby • Diamond •  Blood Diamond
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