This species holds a special fascination for me, being extinct in the UK, but still appearing in the Butterfly books of my youth. 

The leaden blue male upper-side is superb when fresh, and I will never tire of trying to achieve a special butterfly photograph of this one. 

In it's Southern range, for example, in Greece and Turkey, the underside sports orange lunules, and occasionally vestigial traces of orange may be seen elsewhere in Europe.