Saudi Arabia: HRH or HH?

Given that there are literally thousands of members of the Saudi Royal Family, chances are good that an expat working in the Kingdom or a Saudi national will at some point meet a Royal.  A question that I have been asked by newly arrived expats is how should someone from the Royal Family be addressed and when does one use His/Her Royal Highness as compared to His/Her Highness.

The sons/daughters and grandsons/grand-daughters of King Abdul Aziz (the founder of the modern Saudi state) are referred to as His/Her Royal Highness (HRH).  Whereas, Royals belonging to what is referred to as the Cadet Line, are referred to as His/Her Highness (HH).

The Cadet line includes the Saud al-Kabir, the Al Jiluwi, the Al Thunayan, the Al Mishari and the Al Farhan, all of which are branches of the Al Saud.  Members of the Cadet branches of the Al Saud do hold high ranking and sensitive positions within the Saudi government, but they are not in line to the throne.  Therefore, Cadet branch members of the Al Saud take the title, His/Her Highness or Prince/Princess but should not be referred to as His/Her Royal Highness.

One should always address a Royal by his or her respective title until or if directed to address any differently.  Never presume or jump to the American familiarity of dropping titles in place of a first name only without being asked to do so.