Hi,
Virginiamb. I see you are on a hunt for a noce ball bag.

Bonanza as you know is a market place and whether a particular item is authentic or not really depends on the seller or the item in my opinion. I think I found the one your are referring to, but it would help if you could use the format in the first post of this thread so that the members can easily look into the item.
Item Name: AUTHENTIC Bottega Veneta BALL DARK NOCE VENETA
Listing number: N/A
Seller name or ID: sohohollister
Working Link:
http://www.bonanza.com/booths/sohohollister/items/AUTHENTIC_Bottega_Veneta_BALL_DARK_NOCE_VENETA
Comments: I believe this is the one
Virginiamb is asking about
As you commented the seller has only two pictures and one is not clear. I would start with asking the seller to provide the pictures that are listed in, again, the first post of this thread.
Clear close-ups of
1. all logos including those on hardware and pressed into leather
2. both sides of the authenticity tag
3. views of zippers and zipper pulls
4. views of the lining
5. outside views of all sides and bottom
6. views of hardware
7. mirror, both sides if applicable
I don't have any experience with this seller, and cannot comment on this particular bag's authenticy as of now. Personally I won't feel very comfortable dealing with a seller with this little information on the item, but if I were really interested I would start a conversation with the seller.
HTH!