Put half of the water and half the fresh kumquats in blender container; blend till coarsely chopped.
Pour into 6-quart kettle.
Remove peel from oranges; scrape off excess white membrane.
Quarter oranges, removing seeds.
Add orange peel and orange to blender container; blend till peel is finely chopped.
Add to kumquat mixture.
Boil, uncovered, for 30 minutes.
Measure mixture (should be about 3 cups) into 3-quart saucepan.
Stir in sugar.
Return to heat.
Bring to full rolling boil; boil hard till mixture sheets off spoon, about 4 to 5 minutes, stirring constantly.
Stir in lemon juice.
Seal in hot, scalded jars.