Pour the juice, water and sugar into a pot and bring to a boil. Once the sugar has fully dissolved, gradually whisk in the gelatin, making sure to mix well after each addition to prevent lump

Pour the mixture into a cube-shaped silicone mold, only filling each cube halfway. Transfer the mold to the fridge and allow the jelly to partially set, about 15 minutes.

Remove the mold from the fridge and place one piece of mandarin orange into each cube, pressing down slightly into the jelly. Then top with the remaining jelly mixture and return to the fridge for a final time to set, about 30 minutes.