Large button Pyralin Celluloid or Bakelite BJs

Not sure if the dark color part is celluloid or bakelite. Light color is pyralin.
It is a 3 part button, with 2 wafer parts and a navy blue or black dome. Looks black, but in the light it is dark blue.
Metal loop shank.
See scan
Condition - Very good.
Measures - 1-7/16" across. (3.7 cm) With dome top to bottom approx. 9/16"

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