The most popular diamond is the white diamond. The price for one caret round diamond are from $4,000 to $15,000 . The prices are depending color, cut and clarity, and fluorescent. Fluorescence's is a big different it a diamond is $10,000 or $13,000. Some exports say Fluorescence's make a diamond look yellow in the sun even if its a D color the whitest on the GIA color scale.
GIA report all diamond have to have a report from some kind of Lab GIA is the best lab because they us the highest standers and they are widely excepted in the diamond industry world wide. Think of the lab report as a finger print of the diamond, they are an unbiased opinion of the diamond.