What we're seeing here is the irrationality of the market, and a demostration that (short term at least) sentiment can and does trump extrinsic value.
Sure, our gold price is relatively stable.
But the default currency for valuing gold is the greenback. I'll grant you that this is purely arbitrary. Nonetheless, it's the 'ruler' against which the relative sentiment towards gold is measured.
So when we see gold dropping against the USD, for whatever reason, we read, correctly, that the overall global sentiment towards the commodity (and by extension, shares in the sector) is bearish. Hence the flow-on to our markets. Now the logic or the illogic of this is fairly moot, because it's not logic that drives such things.
To take this to a ridiculous level - we don't think gold is rising simply because the value is going up in Zimbabwe dollars. Similarly, we shouldn't think it's holding it's value because it's remaining static in AUD terms. Neither of these is the correct instrument of measure. (And yes, the difference is of course that the Zim doesn't effect our local production costs whereas the AUD does, but the analogy stands - we're in a global marketplace).
It's about sentiment. Not logic.
I have a gut feeling that $790 won't hold tonight.