Cognomen เพชรศักดิ์ (เพชรศักดิ์ 
, Phetsak , Petchsak ) , around the globe, is a rare last name. The surname เพชรศักดิ์ is habitual in South-eastern Asia, particularly Thailand, where it is a rare surname. Very seldom, เพชรศักดิ์ is the forename as well as the last name.