Yes Paul, regarding the bit you liked, the whole saga was laced with that kind of attitude which is why I gave up trying to come to an agreement.
The odd thing is the RD number had been checked and some interesting info given about the histoy, so it seemed like the seller knows a little about glass matters. You would think he should know a chip/damage from a nibble.
As this was the only chip on the tray (the base rim doesn't even have any fleabites), there is no room for a mistaken chip identity. Having said that some of the nibbles on the candlesticks were also more like small chips (there are a fair few), but as they are hardly noticable when the sticks are standing I didn't even bother to mention them.
You live and learn!