I bought a laser a while ago. The daggerboard is quite old, and I'm not actually sure if it's class legal. The daggerboard doesn't have any laser stickers or badges. The only marking there is, says G13.
What kind of markings there should be to know it is class legal?
I would say if it looks like a Laser daggerboard and is constructed like a Laser daggerboard, it most likely is a legal Laser daggerboard. I assume yours is of the 1976-2011 style, foam-over-steel-rods and painted white, not wooden & varnished?
Foils supplied by PSE used to have small red stickers; I have an old daggerboard supplied by Sunfish Laser that has a yellow sticker. If these get torn off for whatever reason, the foil certainly doesn't cease to be legal.
The "G13" probably doesn't mean anything. It may have been a temporary identification at a regatta, for instance.
Is there anything specific about that daggerboard that makes you suspect it's a fake?