Wash the limes and lemon. Peel them. Cut out the soft fruit, but remove all the white pith, and cut into small pieces.
Peel and grate the ginger.
Place the pieces of fruit, zest and ginger in a saucepan, add water and bring to the boil.
Fold in the jam sugar and stir while simmering for 5-10. Do a jam test to check the consistency is right.
Pour the jam into sterilised jars. Seal and store in a cool place.
Is your jam/marmalade ready?
How do you check whether jam and marmalade have the right consistency? Place a dish in the fridge when you begin boiling jam or marmalade. Pour a little jam or marmalade into the dish and place it in the fridge again until it has cooled. Then drag a spoon through the jam or marmalade. If the track made by the spoon doesn't close in on itself, the jam/marmalade is ready.