The Cambridge blue has a wingspan of 40-50mm, and as such is sometimes called the giant hairstreak as this falls high on the size range for the family Lycaenidae. The upper side of the wings ranges between a shimmering cobalt blue to turquoise whilst the underside appears grey with scattered black dots. This species exhibits sexual dimorphism (where males and females differ in appearance); males are larger than females and are darker blue in colour whilst females can be as light as a pale green. Unlike males, females have rounded wing apexes (tips), however both sexes have tailed hind wings with a black spot nearby on both upper and undersides.