Here KL is making a reference to royalty probably because his mind naturally flowed there after introducing the precious stone: a diamond.
A diamond is also used to propose, to ask for marriage.
He might be going on off the last line with the “blood diamond” reference.
As far as I know a diamond is a royal stone, (might be a bit off on translation here)
but in that case it would mix in just fine, diamond = royal, blood diamond = royal blood
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