If your camera doesn't do close-up, close-up pictures, try to borrow one which does.
Show details of the piece so your potential buyers can see the quality.
As for delivery, it should be wrapped first in tissue paper, then plenty of bubble-wrap - making sure it is completely padded on all six sides. Pack in a sturdy box with stuff to fill the spare spaces - though not too tightly.
Wrap that box in a couple of layers of bubble wrap, then put it into a second box, with space filler.
Yes, it will make a big parcel, yes, postage will be expensive - you'd be best using Special Delivery so that it will be properly insured.
Your potential buyers should all be aware of all these setbacks - and should be happy to accommodate them if they want this piece.