The mechanization of the minting of coins from precious metals in France made possible the creation, in 1640, of the louis d'or, named after King Louis XIII (1601–43; reigned, 1610–43), who first introduced the coins. This series of gold pieces was part of a reform that changed the minting method from hammered coinage to a more precisely milled and weighed coinage. These coins included three types: the louis, the double louis, and the quadruple louis. It has been customary since the 17th century (incorrectly) to call the quadruple louis the double louis, call the double louis the louis, and call the louis the demi-louis. Alongside these common pieces, three larger-unit coins were manufactured in limited amounts: 20 louis, 16 louis, and eight louis pieces (also incorrectly called ten, eight, and four louis coins). The 20 louis piece was worth 100 livres; it is still the largest and heaviest French gold coin ever minted. These pieces were specimens, made to be used as gifts and to demonstrate the abilities of the Paris mint, not put into circulation. They are the work of Jean Varin (1604–72) of Liège, who was at one time master, guard, engraver, and head of the French mint, which was established at the Louvre.