Oh, what a waste!! Such a beautiful piece of work....ruined! I hate getting broken glass.
This is my own guideline:
When you have packed your glass, if you can't with confidence drop it on the pavement yourself, you haven't packed it well enough....it is as simple as that.
Furthermore, once paid for, the item belongs to the buyer, and it is the sellers 'duty of care' to pack it properly to withstand the postal service.....if the breakage happens in transit, it is the sellers fault, not the Post Office's!!
I always ask for good packaging and a strong cardboard box on the Paypal payment slip, that way I have proof that I requested appropriate packaging, and if the item arrives smashed, I claim from the seller!! Ooo-er Rosie!
I always say I am prepared to cover the extra cost of packing and prefer next day delivery for very delicate items. I will even travel miles to collect rather than trust the sellers packing!!