I suspect the inlays are probably "capiz" shell - which is a commercial name
for the "windowpane oyster", Placuna placenta.  This shell is widely used
for all kinds of craft and inlay work.  The shell is off-white with a slight
silvery luster, and is translucent.  They also dye them, so if your inlays
are colored, they may be dyed capiz.
Paul Monfils
Rhode Island