That's a nice pp58. At least that's what I think it is. Unfaceted it's a PP1
The Perthshire book by Mahoney and McClanahan describes the PP58 as having a top facet in older versions and five and one faceting in 1997. Yours is six and one. Maybe they added another facet in subsequent years?
I have a PP1 in the same color scheme that I picked because it was really perfect like yours.