I currently have dark brown almost black hair but it is coloured and underneath that is years of bleach
so although the artificial colour does take it can fade rather quickly and as I do worry about constant colouring of my hair, with that in mind I have began seeking less abrasive methods and this has lead to me using Natur Vital Colour.

The Natur Vital packs remind me a little of Shaders and Toners which I have no idea if you can still pick up
but basically it is shampoo with pigment particles but unlike those of the past this also has a 
conditioning treatment that once more deposits colour into the hair via Henna which washes out 
after around four washes should you dislike the result.

Truthfully I don't notice any difference in terms of colour when I use this little pack
but in fairness it does state it is for chestnut hair and mine is a good few shades deeper than that.
However that being said it does leave my hair so much more glossy and it is something I reach for
when I have an event or somewhere special to be as it seems to work much like a glossing treatment.

Natur Vital Colour Packs* 5packs/£9.99 via Natur Vital - link