Preheat oven to 325°F.
In a small saucepan over medium heat, combine guava marmalade, honey, brown sugar, Dijon, and water. Bring to a simmer and cook 1 minute, whisking constantly. Remove from heat and set aside.
Place the ham, flat side down in the roasting pan. Brush ½ cup of the glaze on the ham and cover tightly with the foil paper. Bake for 1 to 1½ hours depending on the size of the ham (about 12 minutes per pound).
Increase oven temperature to 425˚F. Uncover the ham and brush with the glaze. Transfer back to the oven for 10 minutes, or until the glaze is caramelized.
Cover the ham with foil again, and rest for 15 minutes. Serve and enjoy!
