Wash, peel and chop the peaches into a large bowl. Using a potato masher or the bottom of a wide glass mash the peaches and measure 4 cups.
Place the mashed peaches into a large stainless steel pot.
To the pot of peaches add the lime zest, pectin, lime juice and the rosemary. Stir well and heat until a full boil is reached.
Boil while stirring constantly for 1 minute.
Add the sugar to the pot and mix well until dissolved.
Return to a full rolling boil and boil for exactly one minute.
Remove the pot from the stove and carefully skim any foam that settles on the top.
Ladle the hot jam into canning hot jars, leaving a ¼ inch headspace. Remove bubbles and wipe the jar rim clean with a damp paper towel.
Place a flat lid on top of the jar and screw on a band just to fingertip tight. Repeat with remaining jam filling each jar and setting aside.
Once jars are fill process for 10 minutes in a hot water bath canner.
Will make 8 half pints. See notes.