Digital Colour Reproduction
The colours shown on your monitor are the result of the screen's ability to interpret a series of three numbers. Known as RGB (Red, Blue and Green), the numbers are combined to best reconstruct the original source of the colour such as produced by a digital camera or scanner.
The problem is further complicated when printing digital images because the RGB numbers have to be converted to CMYK equivalent numbers which the printer uses to control the amounts of cyan, magenta, yellow and black ink or toner used to reproduce the image.
You can see from the diagram that we (visible) can see more colours than our computer screens (RGB) and our printers (CMYK) can reproduce.
All digital equipment types have different restricted ranges in which they can accurately reproduce colour, known as the equipment's colour gamut. Resulting colour inaccuracy is particularly noticeable with subtle shades where a computer monitor for example has to approximate an out-of-gamut colour i.e. a colour that it cannot reproduce naturally.
Although monitor and camera manufacturers have standards with which to reproduce colours accurately, no two monitors or cameras are exactly the same.
So, please accept that the colour of a product purchased online may not be exactly the same as your monitor showed. And some monitors are more accurate than others!