Maybe on the black market items are able to be traded or sold, but gold as a currency we be virtually useless. There would be no more (legal) gold traders, to sell gold bullion for cash to buy items.
Gold is valuable today, outside of jewelry, as a commodity that can openly be traded. People are hedging gold against greenbacks, because they can, and thats whats driving the price of gold and silver up. Take away the ability to use it as a hedge and its value drops.
If gold ownership(and possibly other forms of tangible wealth) is outlawed, then I predict a huge black market. While I can’t predict the relative value of gold in such a world, I’m sure it will still be more coveted than worthless bundles of hyperinflated funny money. Just don’t leave your wheelbarrow unattended outside the state-run store while you buy that rancid loaf of bread with your pile of paper money.