That looks like mahogany cortex to me,could still be a 3 ply,I bought a Mahogany cortex kit in 1979 that was 3 ply,had a nat int bd,with granitone toms.
You never know with Ludwig,but IMO 1850 is way to high without the 18X12,and in comparison to the snare and FT,that looks like a 13 to me.