"Misery" What's the hardest chocolate in the world? "Valentine's day"

Let's make super hard Giri-chocolates (Obligatory chocolates)!
Rules: The chocolate with a higher score on the Mohs hardness scale wins.
Who will be the winner: an arts student (@tax_i_ ) or a sciences student
( @Sugai_Shunki ) from Tokyo University?
This is QuizKnock's first cooking show!