Drain the mangoes and reserve 1 cup of the liquid.
Puree the mangoes and set aside.
Rinse the Sago under running water and drain well.
Combine the mango liquid with the sago, water and sugar in a saucepan. Over a Medium-high heat bring to the boil and reduce heat to low and simmer (stirring often) for 20 minutes or until sago is translucent.
Add the coconut and simmer for 5-6 minutes (the mixture will go thick and the sago will no longer be white).
Stir in the mango puree.
Pour into 6 individual serving bowls OR a large serving dish - but not too deep or it will take to long to set.