I found this useful link -- very readable, very logical:
A most excellent piece, easy to digest. This is the first logical explanation I have seen how Iran could convince other countries to pay in gold. By offering to take much less gold than the current market price (paper gold price) would imply! Instead of offering 17 barrels of crude for each ounce (which India would be stupid to accept), Iran could prove gold's REAL VALUE by offering 300 barrels / oz... There would be takers for that!
Outstanding article. Must read.