Wash the raspberries. Remove half to a thin wire sieve, and mash the berries very well into a bowl, this will remove the seeds and will produce a raspberry puree. The raspberry puree and the remaining whole raspberries should be 3 cups total.
Peel, pit, and small dice the peaches; you will need exactly 1 cup. Side Note: Make sure you have a total of 4 cups of fruit/puree.
Note: Reducing sugar, water, pectin, raspberries, or peaches will result in set failures. USE EXACT AMOUNTS.
Add exactly 3 cups of sugar, 1 cup of water and one packet of pectin to a saucepan.
Bring mixture to a boil on medium high heat, stirring constantly. Boil and stir for 1 minute. Remove from heat.
Quickly stir puree from the mashed raspberries into the hot sugar mixture along with the remaining whole raspberries and diced peaches. Stir until thoroughly mixed.
Pour into clean containers, leaving 1/2 inch space at the top for expansion during freezing; Cover. Let stand at room temperature for 24 hours until set.
Refrigerate up to 3 weeks. Otherwise, store in the freezer for up to 1 year.
Tip: The fruit will float to the top of the jam during the cooling process. Stir the jam once it has cooled and is starting to set. This will allow the fruit to be distributed throughout the jar and it will have a nicer appearance.