FWIW, there are several interesting resources on the web, that I will not link to, (except for
this) but I will mention that mother of pearl (nacre) is subject to different rules depending upon who is doing the import and export and whether they are commercial or private. So if your shipping company can convince the Government that you are the exporter and they are just a facilitator then there should not be an issue with nacre. However if the Government ever decides that the shipping company is the exporter then they would have to do something about the nacre. Given all the finger pointing in the Gibson case if I were in the shipping business, I'd assume that sooner or later the finger would be pointed at me and be prepared by that eventuality either by not accepting certain materials or by filing probably unnecessary paperwork.