I have shined up shells with baby oil and/or Hawaiian Tropic suntan oil. I read it on the internet, that it is safe to shine them up with oils. I have also used food grade glycerin. I don't like using olive or veggie oil, though(that's just me), but they would probably work just fine too.
I like pretty and patterned shells. I usually get a lot, along with corals, when I ocean hunt.
Very cool looking pattern on your shell. Hope the info helps.