Clean & sterilize jars, lids and rings.
Measure 3 cups sugar into a large bowl. Remove ¼ cup sugar and in a separate bowl, mix it with the powered Sure-Jell. Set aside both mixtures; the sugar and Sure-Jell/sugar.
Peel the mangos, remove the seeds and chop into a small 1/2 dice. You will need 5 1/2 cups chopped mango. Clean raspberries, measure 1/2 cup - add both to a heavy bottom stock pan on the stove. Add in the spices, butter and Sure.Jell/sugar mixture and stir thoroughly.
Place mixture over high heat and bring to a boil stirring constantly. When it comes to a hard rolling boil (one that you can't stir down) add the remaining sugar and return to a boil, again stirring constantly.
Boil hard for exactly one minute and remove from heat. Ladle into clean, sterilized jars.
Clean the tops of the jars carefully (so you get a good seal). Place lids on jars and screw on the rings.
Place the jam in a hot water bath for 10 minutes - this will help seal the jars. Remove from heat and place them on a heatproof surface (I usually use a heavy cutting board. You'll hear the jars make a popping noise as they seal. You can check to see if the jars have sealed by pressing down in the center of each jar. If it is sealed, it will not move. If it didn't seal the "button" on the top will pop up & down.