Wash the apricots thoroughly. Cut each apricot in half, remove the pits, and trim away any bruised or damaged spots.
Wash the canning jars, lids, and bands. Sterilize the jars by boiling them in hot water and keep them warm until ready to fill.
In a large heavy-bottomed pot, combine the apricots, lemon juice, and sugar.
Cook over medium-high heat, stirring occasionally, until the mixture comes to a full rolling boil.
Reduce the heat slightly and continue boiling gently for about 25 minutes, stirring frequently, until the jam thickens.
Skim off any foam that rises to the surface using a spoon.
Carefully ladle the hot jam into the warm sterilized jars, leaving ¼ inch of headspace at the top.
Run a clean knife or bubble remover around the inside of each jar to release trapped air bubbles.
Wipe the jar rims clean with a damp cloth, then place the lids and screw on the bands until fingertip tight.
Place a canning rack in a large stockpot and fill it halfway with water. Bring the water to a boil.
Carefully lower the filled jars into the boiling water, ensuring they do not touch each other. Add additional boiling water if necessary so the jars are covered by at least 1 inch of water.
Cover the pot and process the jars in a boiling water bath for 15 minutes.
Remove the jars carefully and place them on a towel-lined countertop. Let them cool undisturbed for 12–24 hours.
Check that each jar has sealed properly before storing in a cool, dark pantry.