What figure(s) of speech or expression are in play here?
Solution 1:
This, unfortunately, is an example of a mixed metaphor.
The first part speaks of a diamond metaphorically, then goes on to say that the implement that destroyed it was "bitter"—a term involving the sensation of taste. Now, one could go on exuding flavors for a very long time before sundering a diamond. More precise might be "sharp" or "incisive" or "hard-edged" (to keep the same meter as the two-syllable "bitter"), and any of these would support the initial metaphor. Instead, "bitter" forces it off in another direction.