What sable brush type is best for watercolours?

Hello Manpreet, hope you are well! Your Winsor and Newton brushes already sound good. I use my own brushes (www.theperfectbrush.co.uk) but you are welcome to use what you already have. Pity that we cannot do in-person sessions as then I provide all the brushes and materials for free, all materials included in the course price. You're right that sable is the best; however I am not a purist and also think that other hairs have their place and that synthetics are equally good. As I say to my students: a good brush won't paint your painting for you but it will count as 30% towards it. The other 30% is a good teacher and the other 30% is practice and the last 10% is just magic/God/nature (ok, these are rough figures and mileage may vary!)

I love the Rocks brush! It has a unique length--all my other fine point brushes are either very short or the brushes they call "liners" here in the U.S. I have only used it so far to ink in our drawing for the Persian Miniature Painting Earth course. I have not experimented with it very much yet to see how much paint it "loads," etc. Working on the unique surface of the starched and burnished watercolor paper has been enough for now.