The Pocket Guide lists three different species of Vestalis damselflies to be found in Peninsular Malaysia and Singapore. All three species look very similar and are best differentiated by studying their appendages.
The Vestalis species from the family Calopterygidae are large damselflies with metallic green body, long legs and broad wings, which actually give them a rather graceful gait when they fly.
Both the above photos show the male damselfly of one of the Vestalis damselflies.
The correct species id can be confirmed based on certain markings on the thorax (specifically for the Vestalis gracilis) and by studying the appendages of the damselfly, as shown below.
Anyway, the males and females of the Vestalis species have similar markings and their colours give them a good camouflage whether they are perched among leaves in the forest or fluttering away to hide. The female can be differentiated by their less brilliant colours and the different appendages. The following photo shows a female Vestalis damselfly.
Here's a photo of the abdomen of the female damselfly:
This species of damselfly fascinates me. Frankly, I have always thought dragonflies to be more captivating than the tiny damselflies, perhaps due to the plasticky faces of the Ischnura species that one often encounters everywhere. But these Vestalis species are large damselflies yet they are graceful, look almost as fragile as the tiny damselflies and they do have nice looking faces too!
I had also come across the male of this species a few months ago at a different location.
UPDATE 12 APRIL 2011: This species is confirmed as the Vestalis gracilis by dragonflyman, C.Y. Choong. Thanks a million!