You have a gorgeous female there! Her cere is the color of an adult female out of breeding condition.
I can tell you she is an adult as indicated by the white iris rings on her eyes. They are done turning color completely, so my guess is at least a year.
Once a bird has lost it's baby features in it's feather coloring and eye color, there isn't a way to tell if she is 1 year vs. 5 years. For example, you can look at it like this.. with dogs, once they are full grown but not yet showing any signs of getting old, you really can't say a definite age, you can just say young adult or middle aged. With dogs, a further clue is looking at the wear of the teeth, so birds have even less to go on.
I'm sure our mutations experts will come along and say what the absolutely gorgeous mutation you have here is... Lacewing? I really don't know, but I can say I am a bit envious .
To be honest, I didn't even notice her front was so pale! It is possible, since greywing and opaline both dilute the body colour, to have such a pale colour of chest. Of course, she could have something else mixed in there but a clear photo showing her chest area would help to confirm that :thumbsup: