Did that, also made sure I had clean shells. (If I remember right, those were the second item info). The dwarf did not take any.
Spent quite a while trying to figure that out... after I ran out of options (quickly expanded my fishing, built a pont, slaugtered one of each shell-bearing things on the map, mined one of each gem-cuttable, made sure there were raw / glob versions + cleaned + small gem + large gem versions of everything) I forked the save for some cheat-testing and created a big assortment of different shells & gems with all of the dwarfs preferences (in the end I got "creative" and even dfhacked some items like "large gem made of angel shell", "blood gems" and "shell made of crystal glass" into the game to cover all the possibilities). Nothing worked, so after reverting the only solution was magma.