p-ink...

...gin?
Originally a cocktail made fashionable in England in the mid 19th century pink gin consisted of a tot of Plymouth Gin and a dash of Angostura bitters.

Ink gin, crafted in the Northern Rivers of New South Wales is ocean blue in colour ...the blueness from infused Butterfly Pea flowers.
Also known as Asian pigeonwings and the Darwin pea, the flower is  native to tropical equatorial Asia where it is used as as a natural food colouring, in traditional medicines and teas and deep fried in batter.

BUT...it does turn pink.
When lemon or lime is added along with a dash of tonic the 'ink' blushes!