Hello, I recently obtained a Benchmade model 51. After awhile, I realized that the anodizing on mine didn't seem up to par with other pictures I've seen. This lead to me googling, taking apart my balisong, and wiping down the liners with windex. To my amazement, the liners turned from gray to a very satisfactory bright blue. Just thought I'd share with hopes that it could help someone else out who may be having the same issue as me 
Before:
After generously wiping with windex and paper towel:
Before:
After generously wiping with windex and paper towel:
