Tsar Boris III. and Giovanna, Princess of Italy (Bulgaria 1930)

Stamp Tsar Boris III. and Giovanna, Princess of Italy it reflects the thematic directions:

A head of state (or chief of state) is the public persona that officially represents the national unity and legitimacy of a sovereign state. In some countries, the head of state is a ceremonial figurehead with limited or no executive power, while in others, the head of state is also the head of government. In countries with parliamentary governments, the head of state is typically a ceremonial figurehead that does not actually guide day-to-day government activities and may not be empowered to exercise any kind of secular political authority (e.g., Queen Elizabeth II as Head of the Commonwealth). In countries where the head of state is also the head of government, the president serves as both a public figurehead and the actual highest ranking political leader who oversees the executive branch (e.g., the President of the United States).

King is the title given to a male monarch in a variety of contexts. The female equivalent is queen regnant (while the title of queen on its own usually refers to the consort of a king). In the context of prehistory, antiquity and contemporary indigenous peoples, the title may refer to tribal kingship. Germanic kingship is cognate with Indo-European traditions of tribal rulership (c.f. Indic rājan, Gothic reiks, and Old Irish rí, etc.) In the context of classical antiquity, king may translate Latin rex or either Greek archon or basileus. In classical European feudalism, the title of king as the ruler of a kingdom is understood as the highest rank in the feudal order, potentially subject, at least nominally, only to an emperor (harking back to the client kings of the Roman Empire). In a modern context, the title may refer to the ruler of one of a number of modern monarchies (either absolute or constitutional). The title of king is used alongside other titles for monarchs, in the West prince, emperor, archduke, duke or grand duke, in the Middle East sultan or emir; etc. Kings, like other royalty, tend to wear purple because purple was an expensive color to wear in the past.

Princess is a title used by a female member of a monarch's family or by a female ruler. The male equivalent is a prince (from Latin princeps, meaning principal citizen). Most often, the term has been used for the consort of a prince, or for the daughter of a monarch. A crown princess can be the heiress apparent to the throne or the spouse of the heir apparent.