The colours on the physical prototype are different to those on my screen.

This is absolutely normal because a screen does not reflect colour in the same way as a printer. Modern printers use four process colours (cyan, magenta, yellow and key) while a screen adds shades of red, green and blue. This difference means that what you see on the screen will never be exactly the same as the colours on the physical product. Just as screens all have different colour calibrations, printing machines do not interpret colour profiles in exactly the same way. However, we obviously use our expertise to make sure there is the least possible difference between the screen and the physical product.

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