A good quality 1 carat diamond ring costs between $6,500 to $7,500 in retail stores, while the same diamond will cost about $3,000 - $4,000 online! On the other hand, the highest quality 1-carat diamond (D color and Flawless) will set you back $10,000 or more (add 40-70% when purchased at a jewelry store).

If you're looking for an engagement ring under $10,000 then I would recommend that you go with something around 0.90-1-carat and 1.5-carat stones depending on your budget and what quality of diamond suits it best! A 2-carat diamond or slightly bigger diamond may be possible if the grade isn't too high.

The primary reason for round being the most expensive diamond shape is that a large amount of the rough stone is lost during the cutting and polishing process. To achieve the fire and brilliance characteristic of the round shape, more of the original is lost than when cutting a fancy shape.