Slice 1 orange in half. Remove any seeds from the halves, but keep the rinds on. Add both halves to a blender.
Juice the remaining oranges and discard the peels.
Add the orange juice and habanero to the blender (atop the two orange halves) and turn on high for a few minutes. Blend until you reach your desired consistency.
Place a pot over medium heat and add the mixture to it.
Squeeze in the juice from the lemon and add sugar to the pan. Stir gently to combine.
Boil slowly for 30-40 minutes or until the marmalade starts to darken in color.
Allow the marmalade to cool for 5 minutes before pouring into a sterile jar.