Maybe it's Ironstone?

I picked up this dainty little thing at a yard sale a few weeks back.

It has the look of  ironstone, but not any markings on the bottom.

I picked it up, with the intent that it would be a sweet piece in a little vignette in my next flea market booth (September, my friends, I'll keep you posted), or on the blog.  But then today, it became a great pen holder on the desk.
This happens a little more often than I should probably admit!
-Jen