The number is .995.
That is 99.5 percent pure gold. Anything below it fails. Anything at or above it passes.
You could stop reading here and be right about ninety percent of the time.
But there is a coin sitting in tens of thousands of American retirement accounts that is only 91.67 percent gold, and it is perfectly legal.
That contradiction is not a loophole someone found. It is written into the statute on purpose, and understanding why will save you from two different expensive mistakes.
So let us do the number properly.