I have used a strong sterling silver daisy magnetic clasp for some pieces, but unfortunately it isn't available any more, neither from Rio Grande where I bought them from nor anywhere else I can see on the Internet. I'd be leery of a weak magnetic clasp if the pearls are at all heavy, personally. What size/length pearl necklaces are we talking about?
Can you manage a large hook and eye? Or a toggle?
Our member @pattye also restrings. (She gave a thumbs up to your other post.) You can click on her username to send her a message if you think you might like her to do the job. She is also on the West Coast.