Gauge is the word used for the thickness of wire.
When purchasing beading/craft wires it helps if you know the gauge (size/thickness) of the wire required. The lower the no. of gauge size the thicker the wire eg. 20gauge wire is thicker than 22gauge wire.
Gauge to inches to millimetres Conversion:
Gauge inches millimetres
18 gauge = .040" = 1.024mm
20 gauge = .032" = .812mm
22 gauge = .025" = .644mm
24 gauge = .020" = .511mm
26 gauge = .016" = .405mm
28 gauge = .013" = .321mm
30 gauge = .010" = .255mm
32 gauge = .0080 = .200mm
If you want to make your own findings it is best to use 18gauge to 24gauge as they are thick wires they will keep their form/shape. Jewellery can also be made by knitting/crocheting beads onto wire. You will need a flexible wire for knitting/crocheting, try 26 to 32 gauge to find a thickness you like working with.
20 gauge wire was used to make this bracelet, while it's flexible enough to bend into shape it is thick & strong to also keep it's shape.
Craft/beading wires are a great addition for any crafters cupboard.