a blocker bet (or stop bet) is when you put a 1/2 pot-2/3 pot bet (or sometimes smaller if you can get away with it like you did) as an alternative to c/c'ing or c/f'ing the river. the idea is that a nonthinking opponent is going to be less likely to bluff or push with a very good but vulnerable hand, so that you can live to see the show down.

I'm sticking by b/f'ing the river. just take a second to think of a calling station's range in this pot...it includes a lot more holdings than diamonds and 4x, doesn't it?