First quarter your kumquats. Then, using a sharp paring knife, separate the peel from inner membrane and seeds, reserving this since it will be the source of pectin for the jam.
Then slice each quarter of a peel into thin slices. Place the seeds and membrane in a cheese cloth and tie tightly. Then fill a large pot with 2 cups of water and 1 1/2 cups of sugar and place the peels and cheese cloth package in the pot.
Bring to a boil and simmer for about 25 minutes until the consistency is thick. Mine took longer, almost an hour, since I had a lot more kumquats. Pour the marmalade into small jars and keep refrigerated.