One of the necklaces I put back into rotation is crystals on a velvet-covered wire, and it closes with a magnetic clasp. Strong enough for a few pieces of crystal. I hate to think you're not wearing favorites because they're difficult to fasten.

On Amazon I read reviews of some of the add-on magnetic clasps that aren't very strong (tiny magnets) but this one sounds good - 14K Gold Magnetic Necklace Clasps and Closures Double Lobster Clasp. One reviewer said long earrings were attracted to it, so she wears shorter earrings with it. Any of these attach once to each end of your necklace then the magnets do the work.

This one is smaller but it has more reviews. Neither of those is very expensive, they're plated or colored.

These two sold by different small businesses, but they look and sound identical. They are more expensive and with more gold. Small business 1:14K Yellow Gold Magnetic Clasp Converter 15.5mm Spring Ring by CRAFT WIRE. Small business 2: 79% of the reviews of this one are good.