Ya! The photo might be a bit much... But I did eat a few (out of thousands ?) of those mussels with pretty darn blue nacre - if not all, at least a wide 'lip' of nearly lapis-like blue. Always thought that a pearl originating from the corresponding mantle tissue is a miracle waiting to happen.
Well, this is a rather blemished miracle, but... it is sold in a curio shell shop after all. And not for much either.
If the pearl itself is not that perfect, at least it demonstrates a very pleasant possibility...
Disclaimer: I'm talking about a single, cheap blue pearl here, NOT red ones. Not even mine. No connection, Whatsoever. I'm not going to turn up with a perfect strand of solid sapphire-blue pearls from the Sea of Tranquility or something [just 
joking - red pearl/blue pearl, the fit sounds too good to let go!]