Heraldicaly, the strap or belt should not be in blue, that is reserved for the Order of the Garter, which is a blue garter/strap/belt. That particular graphic is bad anyway as the belt changes colour to a dark blue as it goes through the buckle, which of course it wouldn't do in reality.

It has always been my understanding that a clan crest badge should be portrayed in monochrome by a clan member. Only the owner of the crest (the clan chief) has the right to portray it in colour. All other use is by his grace.

That having been said - it is your body. You have the right to adorn it as you see fit. Personally, I think that if you were to use black ink on skin only, it would be just as wrong as using other coloured inks. Human flesh is after all not 'white'. So going for colour would be the best bet. If you are going to do it, it might as well be pleasing to everyone's eye.

Regards

Chas