In an AllMusic review, Richie Unterberger writes, "'Heart of Stone' [is] a slow and soulful, dramatic ballad with the kind of vaguely discordant, droning guitars heard on many an early Rolling Stones slow number. What was impressive was how the Jagger/Richards song, though similar in some respect to American soul ballads of the period... was not explicitly derivative of any one blues or soul song that they were covering on their mid-60s records. The lilt of the verses owed something to country music and the mournful harmonies heard on the latter part of the verses added to the overall feeling of melancholy moodiness."[2]
The song sees the singer discuss his life as a womanizer, and how one girl in particular won't break his heart:
There've been so many girls that I've known
I've made so many cry and still I wonder why
Here comes the little girl
I see her walking down the street
She's all by herself, I try and knock her off her feet
But she'll never break, never break, never break, never break,
This heart of stone[1]