Tynusiia, can you also get a screenshot of that? I was checking screenshots of other people - found 3, and each looks like BLUE pearl (not sure though, perhaps water make them blue).
It would be interesting if that would be a truth- considering that both pearls have same notification.
It would also be odd that none has noticed it takes much more than 100. - I noticed that Trululu Gumdrops was updating Shell Seeker achievement for Tibiaroyal I believe, he would update it accordingly. I think he should speak up here ;-)