Today, rectangular diamonds and square diamonds are generally brilliant-cut. Step-cut rectangular diamonds usually have the corners cut off, thus forming the octagonal Emerald cut.

Square, or nearly square, brilliant-cut diamonds are loosely referred to as princess cut diamonds. Narrow rectangular brilliant-cut diamonds are known as baguettes. When the rectangle forms a trapezoid, with the two long sides tapering inward, it is called a tapered baguette. Baguettes are often used as accent diamonds in jewelry.

Princess cut, radiant cut, quadrillion and baguette diamonds are different cutting styles of square and rectangular shapes. They differ from one another in their style and number of facets.

Related is the cushion cut. Cushion cut stones are shaped like a cushion - they have a square shape that is rounded on the edges.

Buying Tip: Judge the attractiveness of the shape by looking at the outline with the unaided eye. It should pleasing to the eye. Watch out for girdles which are too thin as the square corners are more prone to chipping.