Colour conundrum

Have you ever thought about how strange a concept 'shiny black' is? Read on, in a post inspired by a Twitter interchange with Steve Mould of Festival of the Spoken Nerd. (If you haven't seen their show, book now - it's great!)

What colour is the car in the picture?
It's black.
Are you sure?
Of course I'm sure. What's your point?
It's black?
YES! Okay?
Bear with me. How do you know it's black?
Because that's the colour it is.
And how do you know what colour anything is?
This is basic Newtonian stuff, isn't it? White light hits an object. White light is made up of all the colours of the visible spectrum. Some colours are absorbed, the rest re-emitted. And the colours that are re-emitted are the colours we see. Trivial.
So a postbox, for instance?...
Exactly. White light hits a postbox, which absorbs everything except the red photons, which re-emit. And amazingly we see a red postbox. I still don't get your point.
You will. What about a black object?
That's a bit of a special case. We say something is black when it absorbs the whole caboodle. It doesn't re-emit any colours of light. So arguably black isn't a colour at all, it's an absence of colour.
Spot on. So what colour is the car in the picture?
Black.
And yet it is emitting light. It's shiny. And what does shiny mean?
Unless you are a Firefly fan, it means, well, something that shines. The OED says 'Full of light or brightness; luminous...'
So how can that car be black, if it is full of (emitted) light? By your definition, the colour of something is the colour of the light it gives off. What colour light does the shiny car shine with?
Erm, white light?
Exactly. So by your definition of colour, this black car is white. Next we prove that 2+2=16 and rip off the Bank of England.

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