Over medium low heat simmer the butter, brown sugar, cinnamon and nutmeg, stirring frequently about 10 minutes. Remove from the heat and blend in the rum, Dijon mustard, grapefruit juice and crushed pineapple then set the glaze aside.
Remove the wrapper from the ham and using a sharp knife, create a crosshatch pattern on the skin of the ham through the fat without cutting into the meat, first in one direction, then the other. Insert the cloves into each diamond (or square depending on how you sliced).
Preheat the oven to 425 degrees. Put a rack in the bottom of a roasting pan then place the ham in the rack and pour about ½” of water into the roasting pan and roast 30 minutes, uncovered.
Reduce the heat to 325 degrees, baste the ham with some of the glaze and return to the oven. Bake for 1 hour and 10 minutes at 325 degrees, basting every 20 minutes then increase the oven temp to 400 degrees, baste with the remaining glaze and bake for 20 minutes.
Let the ham rest for 30 minutes before slicing.