What about fancy-shaped diamonds like marquise, pear, oval, heart, emerald, princess, radiant, and others? How can a consumer know a fancy-shaped diamond is well cut?

Due to the symmetry of round brilliant-cut diamonds, it is much easier to formulate proportion criteria and strike an optimum balance between brilliance and dispersion. There is currently no universal set of standards constituting ideal proportions for fancy-shapes. With that said, here are some general guidelines:

• The degree of brilliance in a fancy shape can be one way to tell whether it is cut within acceptable proportions or not. A fancy-shaped diamond should be exciting to look at and should dance in the light. It shouldn't suffer from too much "light leakage" through the pavilion.
  
  
• A phenomenon called the "bowtie" effect (an obvious diminished area of brilliance appearing like a bowtie) occurs in certain fancy-shaped diamonds when the proportions are off. Well-cut, fancy-shaped diamonds show only a minimal bowtie effect. This is something your eye will be able to decide.
  
  
• The symmetry of fancy-shaped diamonds is an important consideration. Take a look at how well the two halves of a diamond look when seen from the profile view and the top view. The two halves should display very little differences, and ideally be mirror images of one another. Diamonds with mismatched halves may have been cut that way to save weight.
  
  
• Diamonds with points at their ends, such as marquises, pears, and hearts, should be thick enough at the points to stand up to normal wear and tear. If these diamonds are cut too shallow, a point may be vulnerable to chipping under certain circumstances.