tout_puissantI have this Ducky ISO/Nordic - Grey/Blue PBT Laser engraved keycaps set and it block out the LEDs.
The LEDs don't shine through on the grey caps at all and the blue caps only glows (look at the white k-board picture) a little little bit.
The Esc cap don't belong to this keycaps set, I used this cap to show + removed some caps to show that the blue LEDs are on.