On EL&U it would sometimes be interesting to emphasize only one letter in the word (or just a part of the word), however attempting
cr**ust**
does not give
crust
but
cr*ust*
(the results are even worse if you want to emphasize letter(s) within a word; the above "crust" was achieved with unicode U+2060, an invisible character between square brackets here: ][
)