Remove all stems and leaves, wash the currents, and drain.  

Place the currants in a large (6-8 quart) jam pot or saucepan.  Add 3 cups of water.

Over medium-high heat, bring the mixture to a boil, stirring occasionally.  Reduce the heat to low and simmer, mashing the currants as they become soft with a large spoon, for about 15 minutes.

Place a large fine-mesh sieve or jelly bag over a large bowl, or use a strainer with several layers of cheesecloth.

Ladle or pour the currant mixture into the strainer or sieve and allow the juices to drain through for several hours or overnight. 

Discard the solids and measure the currant juice.  Pour the juice back into the rinsed saucepan used to cook the currents.

Measure the same amount of sugar as you had in currant juice, add to the juice, and stir to dissolve.

Taste the currant juice with sugar and add lemon juice if desired.

Place the pan over high heat and bring the mixture to a boil, stirring occasionally. 

Once the mixture is boiling, stop stirring and allow it to boil until it reaches a firm gel stage using the cold plate test. 

Place a dollop of jelly on a plate that has been in the freezer, and return the plate to the freezer for 1 minute.  Remove the plate again and push your finger against the edge of the jelly dollop.  If it appears to have a skin on it that “wrinkles” when you push it, it has reached the gel stage.  If your finger runs through the jelly, continue boiling for a few more minutes and try another cold plate test until you’ve reached a firm gel stage.

Remove the currant jelly from heat and skim off any foam if necessary.

Ladle or pour the jelly into prepared jars or containers, leaving ¼” headspace at the top.

If canning, process the jars for 10 minutes (or 15 minutes if above 6,000 feet in elevation). The jelly will keep on the pantry shelf for at least 12-18 months. Refrigerate after opening.

If not canning, keep the jelly refrigerated or frozen until ready to eat. It'll keep in the refrigerator for a few weeks, or up to 6 months in the freezer.