Do legit Japanese copies of Pokemon games have grey cartridges or colored?

I'm looking for Japanese versions of the old Gameboy Pokemon games online, and I found a copy of Pokemon Yellow, but it has a grey cartridge, while the American version is yellow. I know that if a Pokemon GBA game is grey, other than Pinball or Mystery Dungeon, it's a counterfeit...Is it the same for old school Gameboy games?Do legit Japanese copies of Pokemon games have grey cartridges or colored?
Yes, it's grey color. Basically every Gameboy games have grey cartridge. It was not Yellow but I bought Japanese Green, Red, and Blue years ago and all of it was grey.