Put all the ingredients in the Instant Pot and pressure cook it on high for 25 minutes.
Do not add any additional water, as the watermelon will release its water.
Once done let the pressure release naturally.
Switch on the Instant Pot initially on saute mode for 20 minutes. (It might take more time if the peel is not cooked or the jam not thickened)
Let it cook, stirring in between. The jam will thicken as it cooks.
Once the mixture reaches a thick consistency or if it reaches a temperature of 104.5 deg c or 220 deg F you are done.
One can check if the jam is done by using a wrinkle test on a cold plate. Once the jam seems to be done, add a drop or teaspoon to the plate. Wait for a minute and then press it against your fingers. If the surface wrinkles it means it is done.
Switch off. Do not let it go over 104.5 deg c or 220 deg F or the jam will ruin.
Once done, carefully remove the inner of the Instant Pot with the help of hand gloves and let it cool completely before filling it in jars.
Once done, let it cool completely and store it in a clean sterile glass jar.
Notes
Standard US-Size cups and spoons used.
Use sterilized glass jars always.
Maintain proper hygiene for longer shelf life.