Step 1Wash the oranges. Remove the outer peel with a vegetable peeler and cut it into thin slivers. You should have about 1 1/2 cups sliced peel.
Step 2Cut away the white pith from the outside of the oranges. Cut the oranges into quarters, remove any inner pith and seeds, then cut into half-inch pieces. You should have about 2 cups cut-up oranges.
Step 3Combine the slivered orange peel, orange pulp and water in a 4-quart saucepan and bring to a boil. Reduce the heat and simmer 5 minutes. Cover and refrigerate 12 to 18 hours.
Step 4Measure fruit and liquid and add three-fourths cup sugar for each cup of fruit mixture. Stir well to combine.
Step 5Bring the mixture to a simmer and cook over medium heat to the jelly point (220 degrees), about 35 to 45 minutes. (Or test by placing a small amount on a chilled plate to see how it will set upon cooling.) If the marmalade seems to be simmering too hard, reduce the heat to medium low. Stir occasionally to prevent sticking.
Step 6Remove the marmalade from the heat and skim off any foam. Ladle into clean jelly jars, filling to one-half inch from the top. Wipe the rims and seal. Cool, then refrigerate.