Shake gin, St-Germain, lemon juice and preserves in a shaker filled 3/4 full with ice.
Double-strain into a chilled couple-style glass.
Cut a wide strip of lemon zest. Squeeze the lemon zest overtop of the drink. Rub the zest around the rim of the glass and drop the lemon zest into the drink.
You can find the preserves here: http://www.rarebirdpreserves.com/Home.html