Cut off the leaf and root end of the rhubarb stalk, then wash the stalk under cool water.  

Dice the rhubarb into small pieces (1/2" or less), peeling the rhubarb if the outer skin is tough and difficult to cut.  You should have approximately 8 cups of diced rhubarb.

Place the rhubarb into a large pot, and add the sugar and fresh lemon juice (or lemon and orange juice).

Gently stir to coat the rhubarb with sugar, and allow the mixture to sit overnight to macerate.  Or bring the mixture to a boil over medium-high heat, stirring often, cook for 2 minutes, then remove from heat and allow to sit for 2 hours.

For a "chunky" jam, continue with step 6.  For a "smooth" texture jam, skip down to step 9, cooking the rhubarb with the juices.

Using a slotted spoon, remove the rhubarb pieces from the pot into a colander, retaining as much juice in the pot as possible.  Place the strained rhubarb in a colander with a bowl under it to catch additional juices.

Cook the juice over medium-high heat until boiling, stirring frequently.  Reduce the heat to medium and cook until the juice has reached 220°F on a candy thermometer or until the juices are not runny when tested on a cold plate.

Once the rhubarb juice has reached the gel stage, carefully add the rhubarb chunks from the colander and any captured juices into the hot juice mixture.

Place the pot with the rhubarb and juices on the stove, and cook over medium-high heat.  Bring this mixture to a boil, stirring frequently to prevent scorching and boiling over.

Cook the jam until it reaches the gel stage, which should take approximately 20 minutes.

Test the jam to see if it has reached the gel stage by using the cold plate test, or until the temperature reaches the gel stage at 220° F.

Ladle or pour the jam into prepared jars or containers.

If canning, process the jars in a water bath canner for 10 minutes (or 15 minutes if above 6,000 feet in elevation).