This is looking great. I like the sparkle PLA.

I wonder if the added sparkles render the filament more abrasive and if it could potentially damage the brass nozzle.

You’d have to test whether light can get through the silver PLA you have. It would certainly be darker than using white but it may work out well.

I did print scaled down test versions to check light properties and to see how difficult it would be to print a sphere (lots of overhang).

I used white PETG, but PLA could have worked too.

However this is a decorative lamp and even though I will only be using a small LED bulb, I didn’t want to see the model droop or deform if temperatures were to get close to 60°C.

PETG can sustain temperatures slightly higher than PLA.