Combine blueberries, 2 cups of the water and lemon zest in a large stainless steel saucepan. Bring to a gentle boil over medium heat and boil gently for 5 minutes.

Transfer to a dampened jelly bag or a strainer lined with several layers of cheesecloth set over a deep bowl. Let drip, undisturbed, for at least 2 hours.

Prepare boiling water canner. Heat jars in simmering water until ready for use. Do not boil. Wash lids in warm soapy water and set bands aside.

Combine sugar and remaining 4 cups water in a clean large stainless steel saucepan. Bring to a boil over medium-high heat, stirring to dissolve sugar, and cook until temperature reaches 230°F, adjusting for altitude. Add blueberry juice. Increase heat to high, bring to a boil and boil for 5 minutes, stirring occasionally. Remove from heat and stir in lemon juice.

Ladle hot Blueberry Syrup into hot jars leaving 1/4 inch headspace. Wipe rim. Center lid on jar. Apply band until fit is fingertip tight.

Process jars in a boiling water canner for 10 minutes, adjusting for altitude. Remove jars and cool. Check lids for seal after 24 hours. Lid should not flex up and down when center is pressed.