Long-tailed finch length. It has a prominent roundish black bib on its throat and upper chest and a long pointed black tail. It has pinkish brown upperparts with paler plumage below its bib over the lower breast and abdomen. It has a grey head, a white ear-patch, and black lores. It has black patches on its upper flanks and its rump and undertail coverts are white. The beak colour of the adult long-tailed finch varies from red through orange to yellow. The subspecies with red beaks is sometimes called Heck's grass finch "Poephila acuticauda hecki", and the nominate subspecies with orange or
Tyrian purple in antiquity because the colour did not easily fade, but instead became brighter with weathering and sunlight. Its significance is such that the name Phoenicia means 'land of purple.' It came in various shades, the most prized being that of "blackish clotted blood". Tyrian purple was expensive: the 4th-century-BC historian Theopompus reported, "Purple for dyes fetched its weight in silver at Colophon" in Asia Minor. The expense meant that purple-dyed textiles became status symbols, whose use was restricted by sumptuary laws. The most senior Roman magistrates wore a "toga praetexta", a white toga edged with a stripe of Tyrian purple.