My first recommendation would be to take some new photos, its not that these are terrible, but the light filtering in from the window has left them a little hazy and it makes it hard to evaluate.
Ok, well first off I love your gems

they look awesome and especially on that eldar scheme they really bring the model out of its Black and white look. The colours fade lovely and the white spots are consistent
The grills; I personally would leave them black, your scheme is black and bone, so you cant really use another colour without destroying it in my opinion. With the bone panelling around the grills i would keep them black, perhaps simply give them some edge highlighting. However, as its black you can always try another colour and see how it works, then revert to black if you dont like.
Other than that, I dont have much else to say

Overall looks like a good paintjob, but i'd like to see it in some better photos, as I dont think these do it much justice.