("please, wait a moment", image from braille.ch)
Vivian Aldridge has a nice website devoted to explaining braille systems for different languages (HT Boing Boing). If I understand correctly, tone is rarely represented for Chinese braille (let's forgive for the moment that "Chinese" is the name of a language family, not a particular language):
In the few examples of Chinese braille that I have come across, the signs for the tones were not used except in the following cases:
- with the syllable yi, for which a good Chinese-German dictionary lists almost 50 different inkprint characters. In this case the indication of the tone helps to limit the number of possible meanings.
- in words where a syllable with a suppressed vowel comes before syllable without a consonant, for example the word sh'yong (try out, test) in which the braille sign for the fourth tone is used instead of the apostrope. In this case the tone sign seems to be used to separate the two syllables.