I have five Wedgwood blue onion plates, 9″ across.

I have consulted my handy Kovels’ New Dictionary of Marks and still can’t figure out when they date from. I’m thinking either 1871 or 1897 based on the Z in the mark, but I really would like some assistance.

Then, of course, if I can get a date, I’d like some help valuing them.
Thanks!
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