[xorbie]

You have 2/3 the pot here. Any reasonable player with any reasonable holding he thinks is good is going to push here, because anything less lets you double up when ahead and see a showdown for cheap when behind.

Also, in a blind battle, and with this board, I'm loving a K high flush. SB could have anything here, from small diamonds (and putting you on a Q), to thinking you are bluffing diamonds and having a Q himself. There is no real reason for either of you to put the other on a monster hand, especially because this guy is not putting you on QQ or any hand that makes a boat (except KK possibly).