Diamonds certainly come in a variety of sizes, colors, and shapes. All diamonds possess intricate combinations of characteristics that make them unique. Most diamonds have minor inclusions and it is these internal markings that are very valuable in identifying your diamond, because there are no two diamonds that have inclusions in exactly the same places.
The other things that you look for are abrasions on the surface, nicks or cavities or cracks that may affect the structural integrity of the diamond.
To examine diamond's clarity, you will need some magnification tool. Dino-Lite Microscope for jewelers has the ability to examine stones, inspect jewelry for repairs, assist in appraisals and make imaging inventory fast and easy
Here are some recommended Dino-Lite digital microscopes to examine diamonds: