Just an information: the official paint scheme of the Inquisitor Hamilkar is black armor with black clothes and silver details, like it seem in the picture? Or the dark look is just an shadow effect from the night background? Thanks.

I don't think there is an official paint scheme for any miniature. I can see it as positive and negative. The positive means more creativity. The negative is that it is more difficult for people with little experience to paint miniatures to make them look good. Studio painters tend to choose better colors and have feeling which colors would match well and look good together. Finally, there is the fluff and I love fluffy armies. Personally, painting my minis I tried to stick to the old and some new art as much as I could. I have seen some inquisitors together with Hamilkar painted according to the old art (red and dark blue). They looked really cool.

Sure, but for Hamilkar I prefer to paint it with an official paint scheme (if there is one), using the picture available in the book. Just like the Cardinal or other characters with name. I could paint him with a red/gold/black or purple/gold/black paint scheme (classic inquisitor paint scheme), but if the original idea of hamilkar is really all black and silver I will use it.

The Brother who paid to get Hamilkar(Himself) in miniature form used the oldschool Inquisitor black and red colourscheme. Just so you know

Well, seem that after all the paint scheme of Hamilkar was like the other classic Inquisitor and the "dark look" it was only some shades of shadow of the night light in the original picture, however I still painted it wil a silver/black paint scheme, you can find it here:
viewtopic.php?f=30&t=1152&start=10

All down to interpretation. The image could be of him wearing his 'Kirkwood campaign uniform', or simply shadow.