Peel the oranges and cut into slices.

Put half of the peels in warm water and let sit for 24 hours.

Change the water 3–4 times during this period.

Squeeze the grapefruits and limes.

Put the oranges together with the preserving sugar, lime juice, and grapefruit juice in a pot and let boil for 5 minutes.

Blend and then sieve the marmalade.

Remove the peels from the water, cut away the white parts, and cut into very small cubes.

Mix the peel into the marmalade.

Fill hot rinsed canning jars, close tightly, and put in a cool place.