OK I found the path: /System/Library/Extensions/IOSCSIArchitectureModelFamily.kext/Contents/Resources
It contains all the SD Card icons, I just dragged it into the Get Info window and that's it, resolved on my own lol!
Next time, you can just select the icon in the Get Info window and use Cmd + X (keyboard shortcut for "Cut") to remove any changes and revert the icon back to its original. Much easier than navigating through system files and the like.