This is a comparison of 1ct ideal cut, G color, VVS1 clarity Cushion cut diamonds (click the dollar amount to be taken directly to the diamond):

Brilliant Earth: $5600

James Allen: $5630

Abazias: $6038

Blue Nile: $6127

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.