G'day Sam,
Grabben Gullen is the town name....and Grabben Gullen Creek is where the sapphires are. It's on the creek where Sapphire Road crosses the creek.
There is no creek called Sapphire Ck and all the surrounding creeks have nothing worthwhile. It takes a while to get to know where the sapphires are as the last two big floods reshuffled them like a deck of cards. Best of luck,
Cheers Wal.