Bring clementine's to a boil and simmer for 1 1/2 hours, keeping the water above the clementine's.
Once the time is up, remove the clementine's from the water and discard the water. Peel all of the clementine's and remove the pith. (The pith is the white part between the peel and the clementine's or oranges.)
Blend the clementines until no lumps remain. Using a sieve, drain as much juice as you can, pressing on the pulp and squeezing the juice out. Add the juice to the pot with the peel, then add water and sugar. Return to medium-high heat, bring the mixture to a boil, stirring constantly to ensure all the sugar is dissolved.
Continue to cook on medium-high heat until the temperature reaches 220°F. Towards the end of cooking the mixture, it does start to bubble a lot, so use a pot that can hold at least double what you are putting into it.
Once you have reached 220°F, remove from heat and put into a mason jar. Cool completely before using. Stir before using, as all of the peel tends to float to the top.
