Unless I am incorrect, the usual recommended practice is to first paint the body of the clear plastic part silver, leaving the lenses unpainted.
Next, the block is painted whatever color the vision block housing is on the actual vehicle: black, dark brown, etc.
Some recommend adding a clear green tint.
But I got to thinking about this and in real life, the glass appears very dark, almost black — with some depth.
So I am left wondering if it might be better to first paint the blocks gloss black, leaving the lens portion unpainted of course. Next, follow up with whatever color needed for the housing.
Or, silver as recommended, but tinting the lens with clear smoke acrylic paint.
This would be for my Panther F and Panther II kits. Modern armor would necessitate a red tint.
Some are indeed green tinted, but it’s usually way overdone.
I myself paint the inside of the clear ones black or silver, black if the vehicle is buttoned up.
Modern anti-laser coating can range from red to purple. As mentoned in another thread today, mylar discs (ridiculously cheap if not free) can be cut up and added to modern vision blocks.
That’s pretty much what I do for clear ones.
IMHO, whatever color you choose to paint, paint the inside surface of the vision block (if it’s clear plastic!). It will look less like it was painted.
Armor glass – and most conventional glass, as well – has a green or blue-green tint to it, with the depth of the tint being a function of the thickness of the glass. However, the thing to remember is that you’re not going to be seeing that color except by the light passing through the glass from the inside of the tank to you, and it’s much darker inside a tank than outside, so you’re more likely to see it as close to black, or with whatever effect any coating on the glass provides, than to have enough light passing through the vision block to show off its color.