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1.
One Of Chicago's Earlier Prominent Street Gangs &
A Faction Of The EL RUKN'S
My uncle was an EL RUKN so when I got older I became a BLACKSTONE.
by JOSHUA CONLEY July 13, 2006
 
2.
a common stone with grace and elegance.
it is gorgeous as it shines in the sun and sparkles on the beach.

also a common last name.
"look at that shiny rock!"
"you mean a blackstone?"
by meganmick December 19, 2009
 
3.
a piece of poop that is actually undigested food
I ate so much celery that when I passed it, I crapped out a bunch of little blackstones!
by ManderPander September 12, 2006