This is another wonderful example of knot work from the Book of Kells. The original, found in the decorated text (in the bow of the letter L)at the beginning of the Gospel of St. Matthew is, as usual, quite small (I am still amazed at how they did that) and is in fact a double line. I used a single line here to keep the size down. Note how this design is one line made from 12 circles.
The pendant in the photo was printed in matte black steel.