I make this marmalade using whatever quantity of cumquats are available at the time.
Cut cumquats in half across the “equator”, squeeze juice and pips into a strainer over a bowl to catch the juice. Slice the 2 halves finely into another bowl. Repeat with all the fruit. Combine finely sliced fruit and juice. Add enough water to just cover the fruit. (Very little water is usually required) Tie pips into a cloth bag and submerge bag into fruit. Cover and leave at room temperature overnight.
Place the contents of the bowl into a saucepan over medium heat, bring to the boil, then simmer for about 30 minutes until the fruit is soft.
Measure the sugar to be the same volume as the chopped fruit and juice. Add the sugar gradually to the simmering fruit and pips, stirring constantly until dissolved. Boil slowly, stirring frequently, until the jam sets on a cold plate – about 30 minutes.
Bottle while hot in sterilised jars and lids.