In a medium saucepan combine cranberries, sugar, rosemary, cinnamon stick, and orange zest.
Juice the blood orange into a measuring cup. Add additional water to yield 2/3 cup of liquid total. If your orange was juicy and juiced 2/3 cup, you can skip this step. Add to the saucepan.
Bring the cranberries to a simmer over medium heat. Stir occasionally while cooking.
The cranberries will burst while cooking, please use caution when stirring. Continue to stir while cooking the jam will reduce and get thick. The jam is done when it is thick, deep red, and all of the cranberries have burst. Discard the rosemary stem and cinnamon stick if using.
Strain the cranberry mixture by pressing through a mesh strainer. Use the back of a runner spatula to press as much of the jam through.
You can leave the jam like this, it will look similar to thick applesauce, or you can smooth it out by blending.
Place the cooled cranberry jam into a blender and blend on high for 30 seconds. If the jam is getting too thick to blend you can add a tiny splash of water to loosen.
Place in jars and store in the refrigerator for up to a month.
Notes
Blending the cranberry jam will brighten the color, flavor, and leave you with a velvety smooth jam.