Gold standard theory does not mandate that all coin be rendered in gold. It does allow for paper money - in the form of gold certificates. The theory is that for every X number of dollars, there is X numbers of ounces of gold.
I would prefer a "pressious metals index" that would be set by congress. This allows the inclusion of all held and unfettered metals. The amount of silver, platinum, etc would be converted to standard gold oz by value based upon current market. Added with the actual (again unfettered) gold oz, this would then tell us how much money can be in circulation.
There is another theory that also uses assets (currency, debt, bonds, etc.) of other nations that are held. I do not like this idea as it creates an association between our money value and other nation's health.
The Treasury would be limited to estimating amount of currency in the total market and the number of oz of gold held (through the pressious metals index). The treasury would then be required to modify the volume of currency printed / distroyed in order to maintain the balance perscribed by Congress.
Congress could change the ratio.
The major problem with the gold standard is:
Availability
Gold, being a finite resource, could allow one to "corner" the market, and control the resource, manipulating the market price, and availability of gold. The Hunt brothers attempted this some time back with silver. They failed, but had they succeeded, the price of silver would have been virtually under the control of a single individual, who would probably NOT have your and my best interest at heart.
South Africa currently produces between a quarter and a third of the gold in the world today. In a gold standard world, they would dictate the price, and we would have little alternative but to pay whatever they asked us to. Every country would lose control of their monetary policy, simply because the source could not be controlled by said country, and the source would be vulverable to manipulation. A prime example of this "cornering" is what DeBeers does currently with diamonds. The price of diamonds are what they are because DeBeers says so, and for no other reason.
I fail to see how reverting to a gold standard would provide any stability to money. Quite the opposite.