Peel grapefruits and oranges thickly, fillet, reserving juice. Place fillets and juice in a suitable bowl. Retain separating skins (the membrane between the segments), but not the outer peel.
Rinse blood oranges with hot water, rub dry, peel outer peel very thinly with a peeler and cut into zests, then chop coarsely. I always use the truffle slicer for this, it works exceptionally well and really razor thin.
Peel the rest of the peel thickly, fillet the fruit (reserving the juice), add the fillets and juice to the other shape, add the separating skins to the rest of the shape.
Gently heat sugar and honey in a jam pot. Then add the fruit mixture, zest and ginger. Shape separating skins into a large spice ball and hang in the crowd.
Simmer the jam for about 45 minutes, after 30 minutes lift out the ball and press the pectin through the lower grid into the fruit mass, continue simmering. Mix in the Grand Marnier. The jam is more like syrup, not exceptionally firm jelly. If you want it to be, omit the separating skins and use preserving sugar and pectin. Fill into sterilized jars.
Of course, the separating skins will also make the jam slightly bitter. Which is quite desirable. If you do not want bitter jam, you should also use jam sugar.