If the name ends in "ian", it must be Armenian
 

Most people around the world associate the ending "ian" in the last name with the  person being of Armenian Heritage.

The meaning of  "ian" in the end of last name of  most Armenians means "son of" or  "belonging to" . Lately in Diaspora, some  Armenians have changed these endings to blend in their host societies. Today in Turkey "oglu" often replaces "ian," while Russian Armenians may change the endings to "ov"; e.g., Gary Kasparov, Serge Parajanov. A name ending in "ian" is not always exclusively Armenian, since the ending can also be occasionally found in names in Irish, Persian, English, Philippine and some other cultures.

Armenian last names generally fall into five specific categories: Aristocracy, Parent, Geography, Occupation or Trait.

Aristocracy:
The ancient Armenian aristocracy ("Nakharar" c lass) was derived from Parthian-Persian stock and many of their names ended in "uni" or "ooni." Most of these families were destroyed over the centuries but some still survive today; e.g., Bagradouni, Rshtuni.

Parent
Many Armenian names are derived from the first names of an ancestor; e.g. Davidian, "son of David," Stepanian, "son of Stepan," or Krikorian, "son of Krikor/Grigor." Until the 19th century, virtually all first names had a religious origin, so most of those last names are also religious.

Geography
Some last names are based on geographic origin and end in "lian" (Turkish) or "tsian" (Armenian). Typical examples are Sivaslian "from Sivas," Urfalian "from Urfa" and Vanetzian "from Van." These names were typically given to an immigrant who migrated from a different region of Armenia. Obviously everyone living in Marash would not call himself or herself "Marashlian".

Occupation
Most last names were taken from the professions of an ancestor. These names frequently originated with the tax collectors who needed to identify all individuals for tax purposes. Typical examples are Najarian "son of a carpenter," Arabian "son of a wagon/ teamster," and Vosgarichian "son of a goldsmith." Many of these occupations are not Armenian, since the tax man (typically a Moslem Turk, Persian, Arab, etc.) would use his own native word for the occupation; e.g., the name Boyajian is based on the Arab/Turkish term "boyaji" "one who dyes." I guess some where along  my ancestry there must have been an Ironsmith and since "Demirdjian", my last name.

Trait
The most confusing and curious names are those based on some trait of an ancestor. Typical examples are Topalian "son of the cripple," Dilsizian "son of the tongueless one," or Sinanian "son of the spearpoint." Many of the origins of these names are unclear unless one understands the original context. As an example, Dilsizian indicates that an ancestor had his tongue cut out by the Turks for using the Armenian language, while the term "Sinan" was a slang term applied to somebody either with a very erect military-like carriage or who was "hung like a horse." Some of these traits are not physical, but rather reflect personality or social status; e.g., Melikian "son of the king" or Harutunian "son of the resurrection." The name Harutunian could be based on an ancestor named Harutune (so-named because he was born around Easter time), or adopted by a convert to Protestantism to show his status as a "born-again Christian."

Many last names today have been shortened or modified to aid pronunciations by non Armenians; e.g., the name Mugerditchian/ Mkrtichian" becomes "Mugar," "Husseniglian," become s "Hewsen," and Samourkashian" becomes "Samour." These abbreviated names often drop the ian" ending, and are not immediately identifiable as being Armenian to an outsider.

 The name categories of Occupation and Trait can differ significantly between Eastern Armenians and Western Armenians, since the eastern names often have Persian, Georgian or Russian roots, while the western names may have Turkish, Arab, or Greek roots.

Names with the prefix "Der" or "Ter" show that one of the ancestors was a "Der Hayr" a married parish priest), a position of great social status among Armenians; e.g., DerBedrosian, Ter Petrosian.

The study of Armenian Names is a fascinating exercise, since virtually every aspect of the culture is reflected in names. There have been extensive studies of Armenian names in the Armenian language, but little has appeared in English and many Armenians (born outside of Armenia) do not understand the significance of their own names.