In the joint reign of King William III and Queen Mary II (1688–1694), the production of bimetallic tin/copper halfpennies continued in 1689, 1690, 1691 and 1692. However the tin coinage was becoming increasingly unpopular because the public did not feel that there was any intrinsic value in the coins and also the corrosion problem had become apparent; even worse, lead counterfeits had started to appear. Just before the queen's death from smallpox in 1694 a copper halfpenny, weighing 9.1–11.7 grams with 28–31 millimetres diameter was reintroduced. The contract for the new coins stipulated that the copper used should be English and the blanks struck at the Mint. It is noticeable that Charles II's Swedish copper halfpennies have toned to a dark red colour, while the William and Mary halfpennies tone to black, presumably because of different impurities in the copper.