Peel quince and clean. Cut into pieces and place immediately into the lemon water to prevent discolouration.
Place quince into steam juicer and make juice according to the manufacturer's instructions. Mix quince juice with orange juice and sugar. Place into a heavy pot, bring to a rapid boil and cook for 3 minutes.
Fill jelly up to the rim into hot sterilized screw-cap jars and briefly put upside down so that a vacuum forms.