I am new to the world of finches -- I have three gouldians (I wanted two, but the guy had a HUGE aviary and was downsizing so he threw in another male for free... who could say no?) They are gorgeous, and I just love love their warbles.
Anyway, I have them in this cage:

It's beautiful, and is a real centerpiece in my dining room/foyer at the front of the house.
It's near a window, but I feel like the birdies need more light. The roof of the cage is solid (except for two wire portions on either side of the rounded top), and it's very... "dark". They haven't seemed to mind yet -- they have been in this cage for a few days now, previously living in a plain wire flight cage.
Any suggestions on how to add some light without ruining the aesthetic look of this cage?
Would you do two clip ons over the wire grates at the top??
Any and all lighting suggestions appreciated.

Thank you!