The price ranges given vary depending upon the actual grade of the diamond. Here is an example of a round cut diamond. Marquises cost about 20 percent more than rounds. Heart shapes cost about the same as rounds. Emerald cuts cost about 20 percent less than rounds.
Ovals shapes cost about the same as rounds.
Princess cuts cost about 10 percent less than rounds. Pear shapes cost about the same as rounds. However, some inclusions visible to the unassisted eye can affect both beauty and durability. Across most clarity grades the beauty is unaffected even though the price is. To determine a diamond's clarity, it is viewed under 10x magnification by a trained eye.