If using the vase then TBH in order to dress the house for selling, I would put pebbles in it. Don't assume everyone is a Mumsnet snob when it comes to that. It's perfectly acceptable especially when appearing mainstream for house selling purposes.
Or you could put in a large-ish ornament from soemwhere like TK Maxx
We're putting our house on the market soon and I'm trying to make the empty fireplace look like something other than, well, an empty fireplace.
Went to TK Maxx and bought a spherical glass vase, about 40cm diameter. I just don't know what to put in it. Flowers are out because I have some (artificial but hopefully not too naff) calla lillies on the fireplace - although they can be moved elsewhere of course.
Any ideas? I've been Googling and checking Pinterest but nothing's jumped out at me so far.