it looks similar to what is often called a 'float bowl' - although I think most of those had a centre piece of some sort - frog or figurine probably, but not a candle I don't think.
Try the Board's search for float bowl and you'll get an idea of what they look like and if this one is possibly the same.
Getting brain into gear now...... I get the feeling we've had pieces with this sort of acid cut back before - I forget now the name given to the process. If I have the right idea, then I think sometimes the non-relief areas are coloured? But then I could be way off course.

think I'm wrong with that suggestion - confusing this piece with something else unrelated I'm sure.