Can you give us an example? If you're talking about the 'Diamond if you like, subscribe for more!'-type signs that people will put in the description of their submissions, those were user-made. You can ask the creator if it's ok if you use that image too, or you can try to make your own. As a warning, though, a lot of people seem to think it's ok to take those images from others without asking their permission first. This is considered stealing. All in all your best bet would probably be to try to make one yourself, or contact one of the many graphic artists on these forums to make one for you.