Calopteryx virgo can reach a body length of 49–54 millimetres (1.9–2.1 in), with a length of hindwings of 31–37 millimetres (1.2–1.5 in).
These large, dark damselflies have small hemispherical eyes located laterally on the head, two pair of wings similar in shape and a slender abdomen.
The basal area of the wings is transparent, otherwise wings are uniformly colored.
The wings are also traversed by a dense network of veins.
This species presents an evident sexual dimorphism in colour pattern.

The male usually has much more extensive pigmentation on the wings than other Calopteryx species in its range: in the south east of its range (the Balkans and Turkey) the wings are entirely metallic blue while in other areas, there are clear areas at the base and tip of the wing.
Immature males show brown wings, as the metallic blue wing color develops only with age.
 They have metallic blue-green bodies and blue-green eyes.

The female has dark brown iridescent wings, a white patch near the tip of the wings (called a pseudopterostigma) and a metallic green body with a bronze tip of the abdomen.

This species is rather similar to The Banded Demoiselle (Calopteryx splendens), other British damselfly with coloured wings.
Calopteryx virgo can reach a body length of 49–54 millimetres (1.9–2.1 in), with a length of hindwings of 31–37 millimetres (1.2–1.5 in). These large, dark damselflies have small hemispherical eyes located laterally on the head, two pair of wings similar in shape and a slender abdomen. The basal area of the wings is transparent, otherwise wings are uniformly colored. The wings are also traversed by a dense network of veins. This species presents an evident sexual dimorphism in colour pattern.
The male usually has much more extensive pigmentation on the wings than other Calopteryx species in its range: in the south east of its range (the Balkans and Turkey) the wings are entirely metallic blue while in other areas, there are clear areas at the base and tip of the wing. Immature males show brown wings, as the metallic blue wing color develops only with age.  They have metallic blue-green bodies and blue-green eyes.
The female has dark brown iridescent wings, a white patch near the tip of the wings (called a pseudopterostigma) and a metallic green body with a bronze tip of the abdomen.
This species is rather similar to The Banded Demoiselle (Calopteryx splendens), other British damselfly with coloured wings.
Beautiful demoiselle