When these products encounter ninhydrin, a particular bond is formed - a bond that absorbs light of a particular colour.

BBC: Hidden graves found using chemical 'sniffer' technology

Quantum dots are tiny structures made of semiconductors whose size determines, again through rules set by quantum mechanics, exactly what colour and amount of light they produce - and how often they produce it.

BBC: Quantum key distribution with single photons

As they age, the heads and legs become white and the fleece assumes a colour ranging from blue-grey to light grey.

BBC: Protected status for Lakeland Herdwick sheep

Oldman is sporting a pink shirt, his Commissioner Gordon moustache (he is currently filming the latest Batman movie, The Dark Knight Rises) and a pair of heavy-framed, light brown glasses, which match the colour of his hair.

BBC: Gary Oldman's Smiley: 'A little sexier, a little crueller'

Mr Ball next treats us to a brisk description of the human eye (remember rods and cones from school biology?), an explanation of why Newton was right and Goethe wrong about the composite character of white light, and an account of the 19th-century regimentation of the continuous colour spectrum by means of colour wheels and other classifying devices.

ECONOMIST: Science and history of colour