Here are some possibilities:
* Portuguese: Lua is a Portuguese word meaning "moon." It could be a topographic name, given to someone who lived near a place associated with the moon, or a patronymic name, meaning "son/daughter of Lua."
* Hawaiian: Lua is a Hawaiian word meaning "pit" or "hole," and could be a place-based surname.
* Chinese: Lua could be a romanized version of a Chinese surname. There are several Chinese surnames that sound similar when romanized, such as "Lu" or "Liu."
* Other: The surname Lua could also be a variant spelling of other surnames such as "Lúa," "Luar," or "Lúa."
To determine the specific origin of the surname Lua, further research is necessary, considering:
* Family history: Researching family trees and historical records can shed light on the origin and meaning of the surname.
* Geographic location: The location where the surname is most prevalent can provide clues about its origin.
* Language: The language spoken by the family can help determine the origin of the surname.
Without more specific information, it's impossible to definitively say where the last name Lua originated.