Sowerby or Imperial vintage purple slag art glass open lace lattice edge plates

Unmarked pair of purple and white swirled glass plates with pressed pattern, open lace edge. We've been told these are Sowerby pieces, and also been told they're Imperial or Westmoreland glass. And we have no idea which is the correct answer!

They're about 10 1/2" overall diameter, with a few roughnesses on the mold line edges. One of these plates has a professional stapled repair on the lattice (please see photos).

We're not sure if these are antique Victorian glass, or mid 20th century pieces, reproductions or not. They're large, very decorative pieces in any case!