The blue represented a sign of a Brahmin, but the real reason is that blue pigment used was an effective mosquito repellent, so everything started to be blue.
This is Chandrataal lake in Himachal Pradesh. I went there trekking (without my parents letting know). And tell you what guys it is the most beautiful place I have ever seen. REALLY. The lake is at 12 kms trekking from a 16,000 ft altitude pass. The sky is so blue that when the sky meets the outer layer of mountains it give out so much sharp contrast. Much to relief of a person who has never seen such exotic beauty of the Himalayas.