The gold price in London is fixed at 10:30 AM (first fixing) and 3:00 PM (second fixing) in London by representatives of the London Gold Market.
A good article can be found at:
http://www.galmarley.com/FAQs_pages/trading_physical_gold_faqs.htm
and
http://www.nma.org/statistics/gold/gold_investing.asp
Its not a secret my friend.
As for the physical AU, if you walk with a Good London Delivery Bar into a Bullion Dealers office he will not give you that price, there is a margin for handling and all the necessary paperwork. The discount depends on the market.
Different than for example forex there are other risks involved and storage is expensive as well as insurance, so handling physical gold can be a pain, if you know what you are doing it is very profitable and since loans backed by physical precious metal lodged with the bank is reserve capital free when some simple structures are obeyed, leveraging on thats basis allows games which make even more money.
