Tungsten is usually used as the core in fake gold bullion and coins because it is the same weight as gold. The Chinese are now using other metals as the core for fake gold and silver American Eagles. The weight is so close that they fakes cannot be detected by weighing them.
If you buy gold or silver coins, watch the video on this page.
How To Detect Fake Silver Eagle Coins
I just do not understand why the Federal Reserve needs to convert the gold. If they were storing bars for another country, that gold should have been isolated and stored separately. Something doesn't smell right when they have to convert it into a current standard form of bullion. If my gold was being stored, I would want to get my gold back, not an equivalent amount.
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -- Benjamin Franklin