Hoya ruthiae is definitely not a Hoya for beginners, but if you want a challenge, have the prerequisite place to grow it, with very high humidity, warmth, and follow my instructions on the use of net pots and adding oyster shell to the mix, it might be for you.  It took me five long years of patience and dedication to flower this plant, but knowing what I do now, it could probably be done in about two years of high intensity growing.