What type of beading wire should I use when beading with 14mm pearls. Also what type of clasp should be used?
Traditionally, pearls are knotted on silk cord to preserve their nacre (the knots provide a buffer between pearls as they're strung) and because silk offers a beautiful drape to the finished necklace. Accu-Flex® beading wire 0.012-inch or 0.014-inch diameter are good choices as they will fit through the holes on most pearls. French wire and any sort of clasp work to finish the piece beautifully and provide a secure connection that looks professional and will last for years.
Pearls typically have small holes which also make using thread a practical decision. Accu-Flex is also a good choice since it offers strength, a nice drape and it will fit through most holes on pearls depending on the diameter beading wire you choose. For pearls, the 0.012-inch or 0.014-inch diameter are good choices. You can use French wire on the ends, just as you would with silk. Accu-Guard™ wire protectors are another option and serve the same purpose. Use crimp beads/tubes to attach the wire to the clasp of your choice and cover the crimps with crimp covers for that last professional touch.
When working with pearls, it's good to have a pearl reamer on hand as the drill holes can sometimes be too small or irregular. If you come across a pearl or two that you just can't string onto your wire, pull out your pearl reamer and gently enlarge the hole following the manufacturer's directions.