If you use a cup and saucer, should you use a coaster under the saucer?

[Mushroomwithaview]

Or is the saucer the coaster?

The saucer is the coaster although some have a particularly rough bottom, so might scratch the table.

I suppose it depends on how well they're made.

I do.

I use a coaster in the living room because the coffee table is glass and I don't want to crash china on glass, but I don't bother on the dining table.

Just wondered what the 'rule' was.

It's the sort of thing that I would have asked my lovely granny. It's funny how the oddest things make you miss someone.

As I understand it, a doily under a saucer to protect the table from scuffs (wooden tables in them there olden days).