Updated: Apr 29, 2018
For those of you interested in this miracle change of colour, the answer is as follows:
The fruit came before the colour. The word “orange” derives from the Arabic naranj - in Spanish it is naranja - and arrived in English as “narange” in the 14th century. Eventually, the initial “n” was lost. Orange was first used as the name for a colour in 1542. Oranges are unknown in the wild. They are in fact a hybrid of tangerines and the pomelo / grapefruit (which is pale green or yellow), and were first cultivated in south-east Asia. At this time they weren’t orange, but green. So how have they ended up giving their name to a colour? It’s because oranges are a subtropical, not tropical fruit. The colour of an orange depends on where it grows. In more temperate climes, its green skin turns orange when the weather cools; but in countries where it’s always hot, the chlorophyll is preserved and the fruit stays green. That is why, during the first growth spurt during the summer, our oranges are actually green. They eventually turn a gorgeous orange as the temperatures drop during Autumn. And, by the way, you can’t tell the ripeness of an orange by its colour, no matter where it’s from. If an orange is unpicked, it can stay on the tree until the next season, during which time fluctuations in temperature can make it turn from green to orange and back to green again without the quality or flavour being affected. What consumers probably don't realize is that there are a lot of shenanigans where sale of food is concerned, and fruit is no exception. Since most people associate green fruit with unripe fruit, it often happens that green oranges in the United States and Europe have to be coloured to be sellable. Sometimes they are exposed to ethylene gas, which breaks down chlorophyll. Or they are shocked with cold, or covered in wax. Some are scrubbed down with detergent and some are just dipped in dye. Anything for a sale, sadly.