Bead Wire

You've decided to use bead stringing wire because it suits the look you want for your project and you like the idea of the durability of wire. Now, you've got to figure out which wire to use. 

The beading wire you choose to string your beads on depends on the type of jewelry you are making (and often simply on personal preference), but there are a few basic guidelines concerning wire hardness, wire shape, and wire size to help you make an informed selection:
Dead Soft:

Wire is extremely soft and flexible. It can be easily bent and is excellent for making rounded shapes. It works great for wire wrapping and sculpting projects. The disadvantage is that it doesn't hold its shape when weight or pressure is applied.

Half Hard:

Wire is slightly stiffer. It's excellent for making tight bends, for making loops, and for wrapping around itself. Maintain its shape under stress.
Hard Wire is very stiff, easily holds its shape, and is excellent for clasps. It may be very difficult to use for intricate designs.

Wire Shapes:

Jewelry wire is made in several shapes. The "shape" refers to the shape of the cut end. Wire can be round, square, or half-round. Round wire is the most commonly used, but square and half-round wire are available. Half round wire can be wrapped around other pieces of wire to connect them. The corners of square wire are used to add visual interest; square wire can also be twisted to create pleasing effects.Wire Sizes:

In general, always pick the largest size wire that will fit through the hole in the beads you want to string. The size or thickness of wire is measured in gauge or millimeters. Wire used in jewelry making ranges from 10-gauge to 36-gauge. The smaller the gauge number, the thicker the wire will be.

Here are the most common wire sizes:
14-16 gauge (1.65 mm-1.3 mm) Used for clasps, napkin rings, or as a base for stiff bracelets,
18 gauge (1.0 mm) Used for clasps, beads with large holes, lampwork, metal, or as a base.

20 gauge (.80 mm) Used for findings such as earwires, jump rings, and headpins and for stringing glass beads.

22 gauge (.65 mm) A very useful size because the wire is fairly thick, but most beads still fit on it.
24-26 gauge (.5 mm-.4 mm) Suitable for wrapping very small beads and for stringing beads with small holes.
28-30 gauge (.32 mm-.26 mm) Used for free form wrapping of small beads (like seed beads) and for knitting and crocheting with wire.

Choosing the bead stringing wire that best fits your project isn't hard if you're familiar with the basics of wire hardness, wire shape, and wire size. Have fun and don't be afraid to experiment to achieve the wired design you're dreaming of.