Dilute FeCl3 colour is darker at 5e-4M than at 5e-3M. Why?

I did two different dilutions of $$\ce{FeCl3}$$ (within a $$\pu{1h}$$ timespan) from $$\pu{0.05 M}$$, and the one with $$\pu{5E-4 M}$$ concentration looked a darker orange than the one with $$\pu{5E-3 M}$$.

The picture shows on the left: $$\pu{5E-3 M}$$ (I erased the label on the flask); on the right: $$\pu{5E-4 M}$$

I did a test with litmus paper, which showed that the more concentrated one ($$\pu{E-3}$$) was more acidic, which makes sense. I also did a rates test ($$\ce{FeCl3 + H2O2}$$), and the more concentrated one made the reaction happen faster, which again makes sense. Why, then, does the more concentrated $$\ce{FeCl3}$$ look lighter coloured?

Since I had made the more dilute one ($$\pu{E-4}$$) before, I thought there might have been more time for the ferric hydroxide to precipitate and form a darker colour. But I had only left it for $$\pu{1h}$$. I also thought that since the more concentrated one looked greenish, $$\ce{FeCl2}$$ might have been made, yet this does not seem plausible as $$\ce{FeCl3}$$ is more stable.

• FeCl3 hydrolyses if pH is too low, so if you non acidified solution dilute it too much, it precipitates. I.e. it's darker because of precipitate of Fe2O3 (aq). – Mithoron Nov 9 '18 at 19:43