I've to describe this protein but I'm unable to understand it's properties properly. Can someone suggest me about the clusters formed? And which protein crystal is best seen?
your crystals seem to grow from the same nucleation point. This is not unusual and nothing to worry about. In the attached image I see many single crystals that you can use for mounting and data collection.
This clustering seems to be intrinsic for your protein in this particular crystallization condition. In another condition it may bahave differently.
We have solved crystal structures even from broken pieces of such clusters. For that you would need standard accupuncture needles from the pharmacy (two of them). By gentle manipulation under the stereo microscope you would be able to dissect them.
You could also try microseeding or crystallization in 0.1-0.4% low melting agarose to slow down diffusion - that may (or not) improve this clustering behavior.
But as mentioned before - you seem to have enough single crystals to test for cryo-conditions, diffraction behavior, etc.
I totally agree with Magdalena Schacherl. Some of my protein crystals also cluster in exactly the same way and it was not a big problem to fish a singular one to put in the X-ray beam.
Apart from that I would say that your crystals look really nice...I would like to have one of those!! Congratzzz!