I have also noticed the phenomenon recorded by both Steve Croxford and Garry Chambers, regarding the relatively dull and 'blotchy' appearance of newly-emerged male Emperors. I'm sure Alexander Henderson is correct in his analysis of when the purple iridescence is best observed (see replies to SC), relating to the play of light on the scales; it is often easier to 'get purple' under the suffused light conditions resulting from thin cloud cover. However, I think there is an additional factor at play when it comes to these particular individuals, which I'm sure are both in the early hours of adulthood. I have also observed a very similar if not identical situation with the iridescent purple 'flash' in female Purple Hairstreak; when they are still in the earlier stages of 'drying off' it isn't possible to view a particularly rich, strong colour. I suspect that molecules of fluid still adhering to the wings are interfering with the potential effects of refraction and reflection, as light strikes the microstructured surface of the scales. As the wings dry off we see the gradual development of the purple brilliance we know and love. Here's one of my own.