1 1/2oz Gin (Aviation)
3/4 oz Fresh Ruby Grapefruit Juice
1/2 oz Pierre-Ferrand Dry Curacao
1/2 oz Grapefruit-Rosemary Syrup
Shake, strain. Express grapefruit peel, garnish with grapefruit peel.
This works even better with Piggyback Rye.
Try with other base spirits, it seems to work pretty well with most!