Bump - I looked into this whole affair again, because I need some paint doing again after someone scraped the door whilst parked
I said in the OP that my paint code is 245A, but it isn't, it's 245 without an A. Both are called Blu Chiaia di Luna. That said, I've never actually told anyone the code - just shown them the badge in the boot.
Here is a 245
car, AFAIK like mine:
DSCN1214.jpg Photo by cookci | Photobucket
Here is a 245/A
All of which appear to be black with a blue tint, just like my recent paint disasters.
So, I guess: beware the suffix! Of course you would replace a paint colour with a completely different one and keep almost the same code!