Pronunciation: [jˈa͡ʊstə͡ʊn] (IPA)
Correct spelling for the English word "youstone" is [jˈa͡ʊstə͡ʊn], [jˈaʊstəʊn], [j_ˈaʊ_s_t_əʊ_n] (IPA phonetic alphabet).
Correct spelling for youstone