When a person wants to surprise their loved one with a custom-designed engagement ring, their goal is usually to create something unique and special. After all, if you want what everyone else is popping the question with, you could just buy a ring off the shelf. So, how can you design a ring that will truly be unique? Here are five things you might do. 1. Use Colorful Stones Many people buy into the idea that only a diamond should be used for an engagement ring.