A word of warning: Colour matching of a spectacle lens tint is not an exact science. Some lens polymers will absorb tint colours better than other lens polymers. To attempt to ensure consistent tinting results, lens dyes need to be from the same manufacturer and from the same batch, which is a near impossible task. In addition, lenses may tint differently depending on the particular laboratory’s processing and curing techniques. It’s obviously not as simple as it seems. The best that one can hope for is an approximate tint match and that is why it is always recommended to tint a pair of lenses and not only one lens.