Hi!
Blueish! The Nicasil liner in all OS engines is a little blueish in colour.......that's perfectly normal.
If the nickel has peeled away the brass underneath is yellow and not blue....
Over here in Europe (Sweden) I don't think anyone has heard of any OS engine peeling nickel from a cylinderliner or heard this happen to any other ABC or AAC neither!! I have definitly not.. and I have been into this hobby/sport for more than 27 years.

Regards!

Jan K
Sweden