I did this up as a gift for a friend. It went together really fast.
The necklace uses a mother of pearl pendant, size 11 seeds, and top drilled potato pearls. I used a mother of pearl button for the clasp.
I use the mother of pearl buttons for clasp pretty often. One - they're pretty. Two: I found several packages of them on sale! Three: I use pearls and mother of pearl often - so they match.