Soak the gelatine leaves in a bowl of cold water. Squeeze out the water, then put them in a Bain-marie and cover with the fruit juice.
Add the caster sugar and gently heat until the sugar and gelatine have dissolved.
If using, remove from the heat and add the liqueur.
If using a mould, scrunch up some foil on a tray and upend the mould on to it. Pour in a thin layer of jelly, about 5mm in depth, into the mould or bowl.
Using the paint brush, transfer the gold leaf pieces onto the thin jelly layer.
Then pour in some more jelly, to about 3cm depth and add some of the clementine segments. Put it into the fridge to set.
Once set, add half of the remaining jelly and more clementine segments. Return to the fridge to set again. Repeat as necessary until you have used up all the jelly and most of the clementine segments. (You will need a few for decoration).
Return to the fridge to set completely.
After 4 to 6 hours you can unmould the jelly or simply serve from the bowl.
Wet your presentation plate beforehand so that you can position the jelly, then unmould the jelly on to it. Decorative with the remaining clementine segments and serve.