Swiss 20-franc gold coin featuring the head of a woman. A Swiss 10-franc gold coin is known as a 1/2 Vreneli. The 20-franc pieces have a fine gold content of 5.806 grammes and a gross weight of 6.45 grams. As in the case of other gold coins, the trading price is determined by supply and demand. The Vreneli is no longer accepted as legal tender in Switzerland.