Ladle blueberry jam into hot sterilized half-pint jars. Leave 1/4 inch headspace.
Wipe rim of jars with damp cloth or paper towel to remove any sugar residue ensuring a good, tight seal. Screw on lids and ring bands.
Place jars on canning rack in water-bath canner. Add enough simmering water to cover 1 to 2 inches above top of jars. Bring water to rolling boil.
Process for 15 minutes in a boiling water-bath canner. Then turn off heat. Remove lid (lifting so steam escapes AWAY from you. Let sit 5 minutes.
Using canning jar lifter to remove jars from water, place on dry towel or wooden cutting board. Let sit undisturbed until completely cool.
After cooling, check for proper seal. Remove ring bands, press in center of lid to find concave dimple. Carefully lift jar by the edge of the lid. The lid should hold.
Label jars with contents and date of processing. Store sealed jars in pantry. Store unsealed jars in refrigerator to be used immediately.