The aura book I listened to and my reiki lady says the the aura color of love and kindness and warmth is rose pink. Supposedly the writer of the book says she can see aura colors.
Whether this is true or not does not necessarily reflect the nature of the color itself. Brown for example or black and grey were negative aural colors.
I however personally love brown and grey and black for many different reasons. Though chocolate brown is my favorite.
So apart from that I suppose it would be very personal and doubt there is a universal color as signified by the different answers above.
When choosing colors for my apartment I googled color therapy and color history. It was interesting and amusing to read the results. Some of it was based on chakras and auras, others based on studies, other reasoning based on culture. Blue was scientifcally based appetite suppressent, because not many foods are naturally found to be blue, and may be a warning sign of mold. I cannot specifically remember a color for kindness. Though orange had a wide range from culturally buddhist orange of wisdom and enlightenment to scientifically one of agression. Also I think there was a western society that also viewed it as an agressive color.