I have always had natural dark blond hair (well, the color is difficult to define - something like honey/straw/cooper blond), and liked that a lot. When I have recently noticed that my hair is loosing the natural lightness and becoming a tad darker and more to the gray shade side, I decided to look for something to enhance the color. I have bought shampoo, balsam and spray. While shampoo and balsam are nice, I did not notice immediate change.
However, the spray did what it was advertised. I usually do not color my hair, nor use hair-dryers, so they are quite healthy. After using 3 times as advised, the hair shade became lighter. My hair stylist did not find any hair damage and agreed that the lighter color suits me better than the one growing back. However now I am wondering how to refresh color on the roots. While the color difference is not very pronounced and I would not advice to lighten dark hair or roots, it works great to accent your natural color.
The photo shows difference between the freshly grown hair at the root (several cm) and lighter downwards.