So you've decided to use beads on your necklace even though their holes are different sizes? Here are some hints:

Bead Hole Is Too Small

• Using a pin or piece of wire, you can make a wire loop on one end and turn the bead with a too-small hole into a dangle or chain link.

• Another way to deal with beads that have a too-small hole is to purchase a bead reamer. Sometimes these are called pearl reamers because pearls have notoriously small holes. This is a small tool with a very fine corkscrew on the end that you can use to enlarge the bead hole. 

Bead Hole is Too Large

• Sometimes you can make a large-holed bead work by filling in the hole with smaller, inconspicuous-looking beads. I've had this work a few times but of course you have to not use the small beads right next the the large-holed beads on either side, or it would slide around.
• You can also use a leather cord for the part of the necklace with the large-holed beads to keep them looking straight and then make loops and crimps on the ends of the leather cord to attach them to a thinner cord, chain, wire loop, or ring

Hope this helps and happy beading

--Pam