This is a comparison of a 1.5ct ideal cut, E color, VS2 clarity princess diamond (click the dollar amount to be taken directly to the diamond):

James Allen: $10,370

Blue Nile: $11,578

Brilliant Earth: $11,730

These diamonds are independently inspected and graded by GIA/AGS, which means you can trust their quality. The quality of these diamonds is identical--the only thing that is different is the price.