Hi Toni,

Lischkeia argenteonitens and L. undosa are both valid species, and fairly
similar in shape, though the former species is much lighter in weight.
However, the outer layer of L. undosa is usually white, and not pearly
(nacreous).  L. argenteonitens sometimes seems to have a very thin whitish
layer overlying the pearl, but other times the white is missing and the
pearl is actually outermost.  Both these species are fairly uncommon.  If
you got a gift as a child, which someone picked up in a tourist shop
somewhere, I suspect another alternative.  There is a species names
Lischkeia alwinae which is white like L. undosa, though not as heavily
sculptured.  It is abundant around Taiwan, and is exported by the thousands
for shellcraft and tourist sales. These are sometimes "pearled" - the outer
layer removed by acid and/or buffing. One of those "commercial" pearled L.
alwinae could be what you have. If you can scan a picture of it, folks on
Conch-L can probably give you a positive ID.

Regards,
Paul M.