The certificate guarantees my doll is truly a one-of-a-kind--no color or sculpt variation will ever be made. If they do, they promise to refund the original customer (me!) the full original purchase price.
This design team wants to keep their work in-house--they need to know where the design originates, which supplies are used, and so forth. They look at their dolls as true works of art. As do I. It's hard not to, especially once exposed to them in person.