1st one- Mr/Ms Chin, right now, wants a ring. 2nd one- Mr/Ms Chin wants a ring in general, on some specific occasions, or regularly(but not necessarily right now) . I have written something about the difference between "-ています"and "-ます"　for the question below: http://www.italki.com/Answers/question/53674.htm

I think that the 1st one is that Mr/Ms Chin is eager to get a ring desperately! the 2nd one is that Mr/Ms Chin tend to want a ring vaguely! so 1st one is I can get a feeling that Mr/Ms Chin really need a ring more than 2nd one!

~ています means is ~ing so, "チンさんは指輪をほしがっています" means "Mr/Ms chin is wanting to get a ring" and "チンさんは指輪をほしがります" means "Mr/Ms chin wants a ring"