Not sure it is mate, mine definitely doesn't have any of the coloured flecks etc, it's pure black.NHB is the colour for the centre part.
When I fitted mine you could see the blue coming through in the sunlight.
Well I just went and checked mine too.
Turns out I've got blue flecks in mine so its NHB too. Shows what I know!
Strange how I've never noticed before, took an LED torch and some really close looking to see them.