Mango Jam

It is my first time to make these mango jams. Although I typically use fresh produce when making jams and jellies (and when canning, generally), I don't have a choice with mangoes. The advantage is that mangoes here are available all year round, coming from Mexico. So I can make these jams whenever. My kids love it so much, they seem to prefer the jam over the plain fruit. I think this would also go well in crepes.

Ingredients:
4 cups finely chopped ripe mangoes (I used the red mangoes variety; tastes like ripe Indian Mangoes; I had no other choice here)
2 tbsp fresh lemon juice
5-1/2 cups sugar
1 packet of sure-jell (there are two in each box)

Instructions:

1. Wash lids and jars in hot water; keep the jars filled with hot water until you are ready to put them in boiling water so they do not get shocked with temperature change (which might cause cracks). Start boiling water in a large pot for sterilizing. Place each jar in boiling water for at least 5 minutes before using (maybe 3-4 jars at a time).
2. Prepare fruit as above. Measure exact amount into a 6- or 8-qt saucepot (mixture might boil over if you use a smaller pot). Stir in lemon juice.
3. Measure exact amount of sugar into separate bowl.
4. Stir in 1 packet (the original direction says 1 box, but I think I got the right consistency with just 1 packet. 1 box contains 2 packets.)
5. Bring mixture to full rolling boil (a boil that does not stop bubbling when stirred) on high heat, stirring constantly.
6. Stir in sugar quickly. Return to full rolling boil and boil exactly 1 minute, stirring constantly.
7. Ladle quickly into prepared jars, filling to within 1/8 inch of tops. Wipe jar rims and threads. Cover with two-piece lids dipped quickly in boiling water (don't boil the lids - will damage the rubbery seal). Screw bands tightly. Place jars upside down on countertop for about 5 minutes before setting them upright. Do this step repeatedly with each jar, and replace each jar whenever you take one out from the sterilizing pot, remembering to take the first one out for ladling jam.) If you have a jar that is not full, you may use unsterile cover, but place this in the fridge and consume this first.