I finally found the answer...again, I found this info on the Bhe Jei site.
Many Maltese people use the term "halos" when describing a Maltese head. While the standard makes no mention of halos they are a characteristic that may enhance the overall appearance of the head. Halos are defined as the darkening of the skin around the eyes. Many times the presence of halos may be connected with good pigmentation, but there have been many outstanding specimens of the breed that do not have extensive halos.