Cook the mango cubes in the quince and orange juice until soft. If you don`t like bits and pieces, you can puree everything now. Otherwise stir in the preserving sugar, bring to the boil and, according to the instructions, let it simmer for 4 minutes. Pour hot into jars and close immediately.
This jam was made because I still had quince juice in the freezer. Since it wasn`t a whole liter, I mixed it with orange juice (bought) and a very ripe mango.
I took the 3: 1 preserving sugar because I had it at home. I think it would also work with the 2: 1 sugar.