When we first tested hearts in the window to see if they would fade, only the pink ones faded quickly. But after a few more weeks, more colors had faded as well.
This heart used to be purple. The other side, exposed to the sun, has faded completely. On this side, the bottom of the heart, the edges have faded from sunlight, leaving only the untouched purple spot in the middle.
The blue candy heart on the left has faded noticeably. Compare it with the unfaded heart on the right.