Bring a large saucepan of water to a boil over medium heat. Add the cumquats and return to a boil. Cook for 1 minute. Drain. Refresh in iced water. Drain and repeat cooking 2 more times to remove any bitterness.
Combine the sugar and 500ml (2 cups) water in a saucepan over medium heat. Bring to a boil, stirring, until the sugar dissolves. Add cumquats. Simmer f