AS 49 seems to begin to say (and I paraphrase to some extent), the lustre of a pristine and untouched coin from 150 years ago can be preserved even as the redness of the fresh copper begins to fade or subdue. That redness in not actually the lustre, and in fact some "red" coins have only the native fresh surface of copper giving it red colour. The pressure of the strike, and good even die contact on a good alloy coin will impart lustre characteristics - in fact there are similar discussions about cartwheel lustre on American Morgan dollars, much of which is similar to copper lustre on our bronzes. This is why some red-brown or even brown coins of same date can have better lustre than red specimens. If this does not ring a bell, don't know what to say except that look at the coins themselves to see what exactly I am trying to convey.