When jaggery syrup boils well, start checking jaggery syrup
Take a little jaggery syrup in a water
The first stage - immerse in the water
The second stage - syrups stays in water but we can't roll it
The third stage- syrup stays in the water and you can combine it into a soft ball (not so firm and you can easily press it)
The fourth stage- syrup stays in the water and you can combine it into a ball (it turns firm in few seconds). That's is the consistency we are looking for. Avoid hard/ stone consistency