Paint colour charts have been around for years. Most of the colour charts produced nowadays are mass-produced using Litho print processes and match the colours of the paint using CMKY to Pantone colour matching.
The problem with producing mass-produced colour charts is if a designer colour that has been specifically formulated which is not on the Pantone colour chart, it might not be exactly the same as any of the available colours, so they have to choose the nearest match. Therefore when the customer buys the paint it will not match what is in the tin. It might be one or two shades or hues out. Whilst this may not be an issue in a small area a slight difference can have a huge impact on a large room area.
Some companies such as Harmony Paints produce hand made colour charts which are made by actually painting the colours onto labels or other companies spray paint the paint onto paper. These are real samples of the paint so when the customer gets a colour card they are seeing an actual sample of the paint rather than a printed image of what the paint might look like.
Ordering in this way ensures a more accurate representation because the customer is then going to get exactly the same paint colour when they order it.
If you want to know whether the colour chart is a real sample of paint then always check with the company you are buying from what type of colour charts they produce first. If necessary order a sample pot or a colour swatch as well before ordering any paint. This saves you a lot of money in the long run.
Hand painted swatches of various sizes usually from A5 to A4 which the customer can then place on the wall to see what the colour looks like. It also means the customer does not actually paint the room and can move the swatch around to see what the colour looks like under various different lighting sources, for example in dark corners or directly by a window.