EDIT: Some context: "First, all financial instruments are accounting creatures. They are the asset of the bearer and the liability of the issuer. Gold coins were the liability of, e.g., the King, Federal Reserve notes are liability of the Federal Reserve, and coins are the liability of the Treasury."
An ounce of gold is worth a lot even prior to being minted into a coin. As such you could melt it, cut it in half, etc and it would retain it's value. That means it might technically be the liability of the government or the king, but practically speaking they're not. I could buy krugerrands, francs, golden eagles or whatever, melt them down and make jewelry out of them and it doesn't screw up the books of any of their issuers.