For sure, glowing. So I wanted to make a reproduction of another tile ,and I picked a more modern one from my Tile Book - one by Ann Wynn Reeves from 1974. It is a great looking purple butterfly on blue. However, there are some hints from the image of it that there are multiple layers of different colours of glaze.
This is what it looked like with the ‘base’ layers of colour and varnish:
Quite nice, but too green. The plan was to put some blues on top.
Adding extra layers did not necessarily make it that much better. At some point, I got annoyed and started removing layers again. This brought the underlying colours through, but … well:
The final version is interesting, and it does look a little like it is glowing from the inside, but not at all like the original. Not terrible, but not quite what I wanted.