Very speculative; but if you wanted to manipulate the gold market, would it be preferable to buy/sell ETF's ? As at the end of the day, you are trading pieces of paper rather than the real thing. I'd happily sell IOU's if I know that in a worse case scenario I would default.
Are ETF's backed by leased gold? Didn't somebody mention in January that a gold ETF apparently added more gold to their fund than was available for sale?