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.