A yellow or gold colored love-heart. Inexplicably, this displayed as a pink hairy heart on Android 4.4.
On Snapchat, this emoji next to a contact denotes a person that you snap the most, and who also snaps you the most (#1 best friend). The yellow #1 BF heart turns into a red heart after two weeks.
Yellow Heart was approved as part of Unicode 6.0 in 2010 and added to Emoji 1.0 in 2015.
💛 #1 BF Snapchat
💛 Gold Heart