Using a sharp knife or sharp peeler, remove zest from blood oranges, without any bitter white pith.

Chop zest into tiny pieces or slivers.

Cut blood oranges into supremes, setting aside and reserving all pith and membranes (see detailed tips above).

Place all membranes and pith into a cheesecloth that has been folded in half, and create a pouch by bringing the four corners of the cheesecloth together and tying the top with string.

Combine blood orange pieces, zest, water and sugar in large heavy-bottomed pot.

Stir over medium high heat until sugar is dissolved. lower heat and place bag of membranes and pith into pot and simmer gently for at least two hours and up to three - or until marmalade has thickened. Do not boil.

To test marmalade for doneness, place a dollop of marmalade on a cold plate and run a spoon through it. If the marmalade gels up a little or forms a "skin" after about thirty seconds, then it's done.

Remove from heat and cool completely before placing in airtight container.

Can be refrigerated without canning for up to 2 weeks safely, or canned for up to 6 months.