Cut santol in half. Scoop out the seeds, rub in colander. There will be very little pulp, but it adds flavor to mix it with the skins which have been sliced very thin like orange peel. (If the fruit is fresh, there is no need to peel it.) Barely cover with water and boil about 40 min before adding sugar. For every cup of pulp, add at least one cup of sugar. For each 10 cups of pulp, also add 1/2 C kalamansi juice. Boil until thickened. Pour in clean jars and cool.