Blue Ivy celebrated her 3rd birthday with a rainbow cake that made everyone on Instagram feel hungry This image appears in the gallery:10 Instagram Pictures You Shouldn't Have Missed This Week (9th January 2015) 2. Blue Ivy celebrated her 3rd birthday with a rainbow cake that made everyone on Instagram feel hungry Picture: Instagram 10 images See the full gallery: 10 Instagram Pictures You Shouldn't Have Missed This Week (9th January 2015)