Some eternal questions plaque first time engagement ring buyers and six prong vs. four prong is one of them. To some it might seem like a small detail and to others it's a question to be pondered into eternity.
Let's start at the basics - what is a prong? Well the prongs basically act like a claw that holds the diamond in place. They are welded to the band to ensure there security and strength for the job of holding the diamond in place.
Four prong settings are great because they use less metal, they allow more of the diamond to show. Depending on their placement which is usually the four corners they can give the diamond a more squarish look. There is some risk with four prong setting that if one prong breaks, the diamond can get loose more easily than in a six prong setting.
Six prong settings, use more metal and therefore protect the diamond better a four prong setting. They often can give a round cut diamond more rounded look vs. four prong settings which can square off a diamond. If a prong is sheared off because there are six of them, chances are the diamond will still be held in place.
How do you choose between the two?
Beyond basic aesthetics, a good rule of thumb is larger diamonds are likely better secured in a six prong settings vs. smaller diamonds would just be too overwhelmed by all that metal they don't warrant six prong setting. Also, if you anticipate being hard on your ring and never taking it off it might be prudent to choose a six prong setting.