Siva Purana (Vidyesvara Samhita) and Agni Purana says that the size of the rudraksha Emblica myrobalan (dhartiphala) is excellent.
Shiva Purana says they are still shiny, solid and thick with thorn-like protrusionsyields worldly pleasures (Vidyesvara Samhita). Shiva purana gives a definite way of choice of rudraksha and also selction of rudraksha.
Furthermore lighter rudraksha more productive it is. Six types to be discarded, especially those defiled by worms, cut, broken, cracked, but thorn-like protrusions, and is not circular. An excellent example is the a natural hole from one end to the other and that which is done by humans is a mediocre a (Madhyama) (Vidyesvara Samhita).
Selection of rudraksha needs some precautions. Choice of rudraksha or choosing proper rudraksha is another thing. But selection of rudraksha which is of proper shape and size and color is important.