This is a comparison of 0.75ct ideal cut, E color, SI1 clarity round diamonds (click the dollar amount to be taken directly to the diamond):

James Allen: $2710

White Flash: $3088

Blue Nile: $3519

Brilliant Earth: $3630

Abazias: $3943

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.