Cut

When choosing a diamond, the appropriate cut really determines the amount of shine a diamond gives off.  If the correct proportion of cut is made, the light will go through the top of the diamond and then come back out the top as well.  This will produce that magnificent sparkle that only a correct cut diamond can offer. 

If a stone is cut too shallow or too deep though, the light will not properly reflect through the diamond, making it duller.  Shallow cut diamonds will only allow light to go directly through the bottom while deep cut diamonds only reflect light out of the side. 

Thus, proper diamond sparkle and shine is truly determined by the proper cut.  It is also important to remember that the shape of the diamond will not, if done properly, affect the cut or quality of the diamond.  Personal shape taste will not detract from the quality of diamond. 

Learn more about the other C’s: color, clarity, and carat.