One of the comments on my original post with a pattern for some celtic coasters mentioned napkin rings and it occured to me that it would be interesting to see if it was possible to make one in a similar way to the coasters.
The coasters suggested that the ring might be too large, so I moved down a size to a 3.5mm hook and was pleased to find that the resulting napkin ring was just perfect. A closer look at the front. And on one of my mended white napkins. I could write out the pattern if anyone is interested though it might be good to add some advice on fitting the four pieces together as it is even trickier than the coasters!