Diamonds are the most common precious-stone choice for traditional engagement rings. There are many different types of diamond cuts, including round or brilliant, oval, marquise, princess and quadrillion. The cost of the cut depends on the amount of labor required to file and set the stone, along with the size of the rough diamond needed to achieve the desired shape.
A round-cut diamond, also known as a brilliant-cut diamond, not only is the most expensive diamond cut, but also the most popular. Round-cut diamonds have a total of 58 facets -- 33 on the crown and 25 on the underside of the diamond. They are the most expensive diamond cut because of the workmanship and skill required, and because more rough diamond is lost during the cutting process.
A princess-cut diamond is a square diamond that features 76 facets, giving it more sparkle and brilliance than emerald or pear-shaped cuts. A princess cut requires great care when setting it into the ring so as not to damage the diamond, making it one of the most expensive cuts around.
A radiant-cut diamond is similar to a princess-cut diamond, but features rounded edges on a square or rectangular stone. It was created in 1977 by Henry Grossbard who, after 17 years of holding an exclusive patent, allowed other jewelers to use the cut. The radiant cut has between 62 and 70 facets on the underside and crown of the diamond.
The Asscher-cut diamond was created by the Asscher brothers in 1902. This square-shaped diamond features an emerald cut with rounded corners. The Asscher-cut diamond is one of the most expensive diamond cuts because it is exclusively patented.