first selection
socket
final selection

After much but not too much research, I found what I needed. The G9 bulb with its socket.
The advice of the type of bulb came from Oscar who told me the G9 and not the G4 because the latter would need the transformer.
I went to a couple of shops and finally opted for the same bulb model but with two different temperatures.
A hot one (3000k) and a neutral one (4000k) so I will test them and see which one is the best with ceramics. I excluded the cold temperature one because it doesn’t reflect the light value I want to transmit.

The bulb was chosen mainly for the fact that it can easily pass through the porcelain opener which is quite narrow.