Example of stress or tone on a consonant
Taking the character 呣 for instance, we can have things like:


m̄



  叹词, 表示疑问。如：呣, 你说什么？(汉语大词典)



ḿ



  歎詞﹐用法同嗯﹐表示疑問﹑不以為然或出乎意外：呣﹐他去幹甚麼？(Longman’s)



m̀



  歎詞﹐用法同嗯﹐表示答應﹑應諾：呣﹐我這就去。(Longman’s)


There is also record of a neutral toned 呣:


m



  叹词, 表示应诺。如：呣, 我知道了。(汉语大词典)


——

嗯 similarly can give us things like:


ń
ň
ǹ