Bluishing is got by thermal treatment , imho unsourceable hands can be restored by brushing + polishing + bluishing . I saw several recipes on a swiss forum 1-2 years ago .
http://forum.horlogerie-suisse.com/view ... es#p193352dark blue = 350° ...
First polish the hands and clean them with solvent .
Use a flat steel plate approx 6to 8 mm thickness x 40mm x 300mm and get it warm to cherry red ...Place it on a stainless steel cooking pan filled with cold water ... place the hands on the warm steel plate, and just when they get the right blue color, push them in cold water . The blue color would be fixed become blue for a short time,