Digitally hand colouring photos to look like real is hard. Lots of people do it and many get it wrong. Even i am still improving my techniques.
I heard on the photo restoration circuit that it wasn’t possible to get results that looked lifelike and that colouring was at best, a gimmick. I have taken that as a challenge with this customers photo, to produce the best result i could given the original that i had. The customer was adamant about the quality they were expecting and worked with me to revise the skin tone 3 times before their vision was met. It turns out they knew just what skin tone they were aiming for and it was a good one.
I have spoken about hand colouring many times and how the quality of the original will depend on the quality of the outcome. If there are a good range of tones or lots of nice greys in the black and white or the converted colour to black and white image then adding colour back will work a whole let better than if the image is all washed out.
Having said that this image was washed out so the tones had to be matched before the colour could be replaced. Its much better than the one tone wash you get when simply adding a layer and setting it to “colour”. It is much more complex than that. The revisions i made were mainly to the tonal range. This was achieved by finding the right shade of grey to allow the colour that was applied to take on the correct hue, or “stick” correctly as i like to say. Before you ask the hair is meant to be that colour.