P.S.  Strombus luhuanus is a light brown to yellowish color, with a black band
along the aperture (mouth) of the shell, and a pink-red interior.  You said
the pen material appeared to resemble the kings crown (which is not actually a
conch, even though it is called that - also the kings crown is from Florida,
not China).  By that, I guess you mean a darker brown color, perhaps with some
lighter markings or stripes?  If so, then the most likely conch would be
Strombus gibberulus, also common in China, and widely used in crafts.
Paul Monfils