19g SWG niobium wire. (18g AWG is this exact same size)
Niobium is a naturally occurring element (41 on the periodic table) and is hypo-allergenic. It is a grey color in it's natural state, but can be anodized in a wide array of colors. When anodized, no color is actually added. An electrical current passed through it that produces an oxide layer that reflects light and lets you see color.
Actual wire diameter .040", 1mm
**Special notes on niobium wire**
If you are coiling or wire wrapping with anodized niobium wire, because the color is caused by an oxide layer, any bending of the wire *may* change the color or shine slightly.
Rainbow wire will have multiple color transitions, however, because of the process, they will not be as close together as on our rings.