Discard the small green stem with the kitchen scissor from each Mulberry. This is a tedious task but needs to be done. Wash the Mulberries gently, and keep aside.

In a nonstick frying pan add the Mulberries, sugar, and lemon juice. Over low heat cook the jam for 15 minutes or until it thickens, mash the Mulberries with the help of a spatula little bit. It’s up to you how much chunky you want the mulberries into the jam. I didn’t mash the Mulberries much, and I liked the way how the jam turned out. It's more like a preserve of sweet Mulberries with a gorgeous deep purple syrup. If you want a thicker jam, you can mash the Mulberries completely using a masher while the jam is cooking.

Do the jam test to check the jam is done or not. For the jam test, after the first 12 minutes put a few drops of the jam on a dry cold plate. Wait for a few seconds, drag a finger through it. If the jam is ready, the parting made by the finger will remain open. If it runs together, cook for some time more. 

Remove from the heat, let the jam sit in the same pan to get completely cold before transferring into a jar.