How to whiten/clean cloisonne on a Golden Star pen

[lflsqrl]

I picked up a Golden Star cloisonne pen yesterday that I'm pretty sure is supposed to be white (or at least, there's a similar pen attributed to Venus that's white: https://evan-fountainpens.blogspot.com/2010/05/703.html) and not its current state of aged-beige. I've read some posts on here about cleaning cloisonne, but nothing about whitening (or at least brightening). Is there really no way to restore the original color? I'm afraid I already know the answer but wanted to check with folks who are more experienced. 

 

Link to my pen, as well as embedded image: https://imgur.com/a/I5MJsqM