Fill a quart mason jar about halfway with fresh blackcurrants. Do not mash the currants.
Add in roughly 5 ounces or 2/3 cup of sugar, lemon juice and gin. The jar should be just about full, but if not add enough gin to fill the jar leaving 1 inch of headspace.
Allow the currants to infuse for 2-3 weeks. Strain and enjoy!
Serve cold with seltzer or tonic.