In a heavy-bottomed pot, combine raspberry juice and sugar.
Cook it over medium high heat, stirring frequently, until sugar is melted.
Increase the heat to high and bring the mixture to full rolling boil, which means the mixture continues to boil even when you stir it. Boil for 10-15 minutes, or until the mixture reaches 215°F (101°C), stirring frequently and skimming off the foam.
Pour the jam into clean jars, cover and cool to room temperature. Store the cooled jams in the fridge for up to 1 month.
Canning instructions: Sterilize the jars by washing them in soapy water and then dropping them in boiling water in a canning pot. (I don’t have a canning pot, so I use my deepest stock pot.) Make sure you use a canning rack on the bottom before putting the jars in, or you can also use a rag. Otherwise, jars will break if they touch hot bottom of the pot.
Place the lids and rings in a boiling water and turn the heat off. Don’t boil the water with the lids, as it reduces the quality of sealing rubber.
Pour the jam into sterile jars, leaving about ¼ inch left from the top.
Run a knife along the inside edges of the jar to remove any air bubbles, trapped in the jam. Be careful not to touch the bottom of the jar if using metal utensils.
Clean the edges of the jars with a wet towel, or paper towel. Place the lids on and tighten the ring around them, but not too tight.
Place the jars into a boiling water in a canning pot with a rack on the bottom. Make sure the jars are covered with at least 4 inches of water. Boil for 10 minutes, then turn the heat off and let the jars sit for 5 minutes before transferring them to a cooling rack.
As the jars cool down, you should hear popping sounds. It’s a sign that the jars are being sealed. Sealed jars can be stored in the pantry for up to 1 year.