Can use wire diameter 0.6 - 0.8mm ( 23 gauge - 20 gauge ) Small diameter wires will make knots easier, but the ring stiffness will not be high. You can overcome this by increasing the number of rings.

How to make Celtic knot ring - Wire Wrapping Ideas With simple steps and simple tools you can do it yourself. Can be replaced with silver wire or gold wire and gemstones for jewelry more valuable Or ...