Convert from once [France] to ounce [troy]

Unit Definition (once [France])
The onça, once, oncia, onza is traditional names for the ounce unit in Romance languages. The French once equals 1/16 livre or about 30.59 grams (1.079 ounce).

Unit Definition (ounce [troy])
The ounce [troy] is a second traditional unit of mass or weight. The troy ounce, traditionally used in pharmacy and jewelry, is 1/12 troy pound, 480 grains, or about 31.1035 grams. Thus the troy ounce equals 192/175 = 1.09714 avoirdupois ounces. This unit is the traditional measure for gold and other precious metals; in particular, the prices of gold and silver quoted in financial markets are the prices per troy ounce. The troy ounce is divided into 20 pennyweight or into 8 troy drams.