I am lucky that I have a blood orange tree in my little citrus orchard. The color is fabulous and the flavor is much less sweet but more intense than navel oranges. Blood oranges have very few seeds so you don't have to worry about removing them (bitter) and the few will float to the top during the cooking process. You can use this recipe using other types of oranges, like navel. —dymnyno
Cut each orange in half and then slice as thinly as possible with a very sharp knife.
Put the sliced orange slices in a large heavy bottomed pot.
Add the water and bring to a boil. Then lower the heat and simmer for 20 minutes.
Turn off the heat, add the sugar and mix. Then leave overnight to develop flavor and color.
The next day; bring the mixture to boil and simmer until the mixture reaches the jelling point of 220 degrees. Use a candy thermometer. This will take longer than you think, so the thermometer is an accurate way of knowing when the jell point is reached.
Stir in the orange liquor (Cointreau or Grand Marnier).
In the meantime, have canning jars and lids sterilized and ready.
Carefully spoon the hot marmalade into each jar, wipe the rims of each jar and screw on the band or seal the jar.