I have experimented a bit with various dyes in salons and at home but always conclude that I like my natural mid brown with kind of chestnut and golden bits best of all. The greys are coming in fast now and I wonder is there a way to save a sample of my natural colour so that in future salons can get it just right when trying to replicate it? Photos are never the same. If I cut a lock will it stay the right colour over time to know?