It is occasionally useful to give the diacritics a different color, for example for the purpose of teaching. For an example of how it would appear, see the Hebrew Wikipedia article Holam, which shows diacritics in a different color using images. Because of the diacritics' combining nature, it's a bit complicated to insert them between separate tags, but possible by writing HTML entities instead of explicit characters. The bigger problem is that modern browsers either ignore this formatting or show it incorrectly.

A test can be found at this js fiddle, which displays different diacritics.