It's fairly common to confuse a diamond's cut with its shape. The cut describes
a diamond's light performance, dimensions and finish. Shape refers to the overall
outline of the diamond when viewed from the top.
Round
The round brilliant cut diamond is by far the most popular and most researched diamond shape available today. For almost 100 years, diamond cutters have been using advanced theories of light behavior and precise mathematical calculations to optimize the fire and brilliance in a round diamond. In addition to being the most popular and researched shape, a round diamond will typically give you more flexibility in terms of balancing cut, color, and clarity grades while still getting the fire and brilliance you want.
Princess
This is our most popular non-round diamond. Its beautiful brilliance and unique cut makes it a favorite for engagement rings. The princess has pointed corners and is traditionally square in shape. When choosing a color grade, consider that while the price of a J-c
olor non-round diamond is exceptional, color may be slightly visible in its corners. Also, princess-cut diamonds can vary greatly in how square or rectangular they are. For a princess diamond shape that is square, look for length-to-width ratios between 1 and 1.05. If you prefer more of a rectangular shape, look for length-to-width ratios greater than 1.10.
Emerald
What makes this shape different is its pavilion, which is cut with rectangular facets to create a unique optical appearance. Due to its larger, open table, this shape highlights the clarity of a diamond. Also, emerald-cut diamonds can vary greatly in how rectangular they are. For the classic emerald-cut shape, look for a length-to-width ratio between 1.30 and 1.40.
Oval
An oval diamond has beautiful brilliance that's similar to a round diamond. Oval diamonds are also very popular as their length can accentuate long, slender fingers. For the most traditional oval diamonds, look for length-to-width ratios between 1.33 and 1.66.
Heart
The heart is the ultimate symbol of love. The unique look of the heart-shaped diamond helps make it a distinctive choice for a variety of diamond jewelry. When choosing a color grade, consider that while the price of a J-color heart shaped diamond is exceptional, color may be slightly visible in its corners. For a more traditional heart-shaped diamond, look for length-to-width ratios between .90 and 1.10.
Marquise
The shape of a marquise diamond can maximize carat weight, giving you a much larger-looking diamond. This brilliant-cut diamond looks beautiful set with round or pear-shaped side stones, and the length of the marquise makes fingers appear long and slender. For the most traditional marquise-cut diamonds, look for length-to-width ratios between 1.75 and 2.25.
Pear 
This brilliant-cut diamond is also called a teardrop for its single point and rounded end. The unique look of the pear shape helps make it a popular choice for a variety of diamond jewelry. If you choose an elongated pear shape, the length of the diamond creates a subtle slimming effect on the fingers. For the most traditional pear-shaped diamond, look for a length-to-width ratio between 1.45 and 1.75.
Radiant
Trimmed corners are the signature of this diamond, and they help make the radiant-cut a popular
and versatile choice for jewelry. A radiant-cut looks equally beautiful set with either baguette or round side-diamonds. Radiant-cut diamonds can vary in their degree of rectangularity. For a radiant diamond shape that is square, look for length-to-width ratios between 1 and 1.05. If you prefer more of a rectangular shape, look for length-to-width ratios greater than 1.10.