Plate Assay Act, 1783

No gold, &c. except fine without alloy, or less by 1 grain only.

XXIX. And be it further enacted, That no finer, refiner, or parter of gold, shall sell, or expose to sale, shall exchange, or expose to be exchanged, any gold, other than and except fine gold, and without any mixture of alloy, or gold less than fine by one grain in the ounce only, upon pain of forfeiting such gold, or the value thereof.