Sister getting married!

Hi all,
Next month my sister is getting married. I’m planning to gift her a diamond ring as she loves diamonds. I’m a designer and was planning to design a ring for her. But I don’t know the jewelry who help to design the ring. I searched for fine diamond jewelry out here and happened to find http://www.pheradiamonds.com/ . I need to know there are any other jewelry. And also how much does they cost?