It involves an orphan girl who has the ability to see and use colored rings floating in the air to travel to other worlds!. Some few others can do the same but she has the almost unique ability to mentally move the rings when she can see them!. During some unauthorized travels she discovers a conspiracy to secure and use several rings to import water from one world to become oil in ours!. (Said fixing of the rings appears to create earthquakes in our world!.) At the end of the book she discovers that she is the clone-daughter of a woman (scientist!?) who fetched her from one of those alternate worlds!.
I've done some Google and Amazon searches but haven't come up with the title, darn it! Does this ring a bell for anyone!?Www@QuestionHome@Com