From a medieval Italian nickname meaning ‘gem, jewel’. It has been chosen in modern times mainly because of its transparent etymology. Among Roman Catholics it is sometimes chosen in honour of St Gemma Galgani (1878–1903), who was the subject of many extraordinary signs of grace, such as ecstasies and the appearance of the stigmata. It was extremely popular in the 1980s but has since faded slightly.
Scottish, English, Dutch, German, Danish, Swedish, and Jewish (Ashkenazic): nickname for a tall person, from Older Scots, Middle English, Middle Dutch, Middle German, and Danish lang ‘long’, Swedish lång.