and jewelers right here in the u.s. are working overtime now to copy that royal engagement ring. miguel marquez reports now from london. >> reporter: william and catherine introduced themselves to the world as the royal couple. officially engaged. nine years in coming, they talked about the moment when william finally popped the question. >> a true romantic. >> i've been planning it for a while. but as every guy out there will know, it takes a certain amount of motivation to get yourself going. so i was planning it and then it just felt really right asking in africa. >> reporter: the ring, which william carried in his backpack for three weeks, waiting for the right moment, carries a significance all its own. >> well, i just hope i look after it. it's very, very special. >> it's my mother's engagement ring. so i thought it was quite nice. obviously she's not going to be around to share in the fun and excitement. this is my way of keeping her close to it all. >> reporter: a bittersweet reminder of his mother, princess diana, and the very ring she first wore 30 years ago.