Holy crap 2kg, that's a lot of Sapphires. Our biggest was probably about 6mmx3mmx3mm, small but great looking. I reckon there must be some better spots there, we're going to try some lower points next time that I selected from google earth. The lack of Spinel amazes me too. We got 17 blue stones from say 0.1 of a cubic metre of wash in the fossicking area.
!00 stones is pretty good going even if small. I reckon a few beauties must come along every now and then, getting enough to keep me interested though.
Our biggest from GG is about 2ct, much bigger than the rest but is a blue bomb. Will probably go to GG next time and then back to Oberon to compare.
Have you tried GG yet?