Exercise 4 is a setting on the stones groups.

As here you are having a few different stones,sit, relax, hands put on the knees, close eye, as in first hand take one stone, leave his for lie, not touch his, think about your feels, which had been a first feels of touching with him, how you are feeling a stone, heavy or easy, warm or cold, are they comfortable for you, if stone bad for you, remove his, wash hands, neutralizing negative energy of the stone, keeping exercise with a next stone, in a few times try return to the first stone, if on this time he is not answered you, thus avoid his.Keep exercise with an other stone, and think about his responses, are you feeling a keys of energy?How they are display, which feels are display, as in a few time put stone in the left hand check what is happening,asking same questions.
Which are differences between left and right hands, how a feeling right hand without a stone, are you feeling stone s colour. After exercise ending look attention on the stone, and write your feels. Doing  this with an other stones, as doing this till a how long you are concentrating  ability a good, as exercises with a different stones are different, resonance on  the matching stone is your natural  and on other time you can feeling an other reactions, but if you long time working with a same stone,thus you reaction is changing.