Cut washed oranges and lemons in half crosswise, then into very thin half-moon slices. Discard any seeds but keep the pith. Place the sliced fruit along with their juices into a large stainless steel pot. Place star anise, cardamom seeds and cinnamon sticks in a piece of clean muslin cloth and tie up with cotton twine. Place the bundle in with the oranges and lemons.
Add the water and bring the mixture to a boil, stirring often. Remove from the heat and stir in the sugar until it dissolves. Cover and let stand overnight at room temperature.
Next day, bring the mixture to a boil. Reduce the heat to low and simmer uncovered.  After one hour remove the muslin cloth spice parcel and discard this. Continue to simmer for a second hour. Turn heat up to medium and boil gently, stirring often, for another 30 minutes. Make sure you skim off any foam that forms on the top. Cook the marmalade until it reaches 105C degrees. It needs to reach this temperature for the pectin to set.
Make sure the marmalade is ready by placing a small amount on a cold plate and refrigerate it until it’s cool. If it’s firm–-neither runny nor hard–- it’s ready. When you push it with your finger it will wrinkle up.  If the marmalade is runny, cook it for another 5 minutes then test again.
When your marmalade is almost ready place the clean jars and lids into a 180C oven and heat until they are too hot to touch. This will sterilise the jars.
When the marmalade is ready using a jam funnel pour it into clean the hot jars, wiping the rims thoroughly with a clean damp paper towel. Seal with the hot lids.
In a large saucepan, place a tea towel or clean chux in the bottom of the pan. Place hot sealed jars of marmalade in the pot resting on the cloth and cover with hot water. Bring to the boil over medium heat and then reduce heat to a simmer and simmer for ten minutes. After ten minutes, carefully remove jars from the pot and allow to cool. You may need to do this in two batches depending on the size of your saucepan.
When cooled to room temperature , chill in the refrigerator. It may take 24-48 hours for the natural pectin to set up properly. Marmalade can be kept in a cool dry place until opened and then store in the refrigerator.