The consulted works concur in tracing this surname to a feminine given name of auspicious and affectionate character, with which girls were wished a luminous and valuable life, comparable to a pearl. E. De Felice notes that it was formed from the term pèrla — or its southern variant pèrna — and places it in the same series as names such as Diamante, Gemma, or Gioia. E. Rossoni adds that Perla would be a derivative of the feminine Latin name Perna, and documents its transformation into a surname as early as 1108, in a deed drawn up in Naples, where a certain Martinus primicerii qui nominatur Perna is mentioned. Rossoni also notes that in some cases the surname could derive from place names.

As to geographic distribution, De Felice and Rossoni agree that both Perla and Perna — the latter far more widespread — predominate in central and southern Italy. F. Miranda specifies that the main concentration is found in Lazio, especially around Rome and Viterbo, with further presence in Piedmont, Apulia, the Marche, Emilia-Romagna, Lombardy, and Calabria. In Sicily, Miranda records localized occurrences in the provinces of Catania, Messina, Agrigento, Enna, Caltanissetta, Palermo, and Syracuse.