Check the 4Cs: cut, color, clarity, and carat weight
Review the diamond’s cut grade for brilliance and sparkle
Inspect color grade for how colorless the diamond appears
Examine clarity grade for internal inclusions and surface blemishes
Compare carat weight with the diamond’s visible size
Look for a grading report from a reputable lab
Verify the report number matches the diamond
Check symmetry and polish grades
Observe the diamond under different lighting conditions
Use magnification to inspect inclusions and surface features
Confirm fluorescence level if relevant
Assess overall eye appeal and light performance
Compare similar diamonds side by side
Buy from a trusted jeweler or seller