Sterilize 6 half pint jars and lids. Keep warm until ready to use. Set up canning pot with rack and enough water to cover jars by 2 inches. Heat water in canning pot to a simmer so it will be ready to boil when you are ready to seal jars.

Put loquats in food processor and pulse a few times to break them up. Don't puree until smooth, you want a little texture, but nothing bigger than a pea.

In a large, heavy-bottomed, nonreactive sauce pot, add loquat pulp and lemon juice. Over low heat, bring to a boil.

When the mixture is boiling, add sugar (and pectin, if using) and increase heat to medium/medium high. Return to a rolling boil while stirring vigorously for the first few minutes.

The jam will boil anywhere from 30 - 40 minutes depending on your fruit. (Mine needed 35 minutes) 

Stir frequently to avoid scorching on the bottom of pot. You will notice that it gets thicker and a little sticky and syrupy. You'll also notice the foam starts to subside - that's sign you're almost there.

When it begins to thicken and it's almost done, add the cardamom and stir.

Remove from heat and ladle into jars, leaving 1/2 inch space. Wipe rims clean with damp paper towel.

Put lids and rings on jars. Tighten to "fingertip tight" (not too tight) and lower jars into water bath. Process for 10 minutes, remove from water and set on a kitchen towel to cool overnight.