When this happens, several customers feel that they know nothing about diamonds, which in turn creates confusion in their mind. One of the most common terms that you will hear when you are looking for diamond engagement rings will certainly be the girdle. In simple words, a girdle can be defined as one of the major parts of a cut diamond. The demarcation line that you can see between the bottom and top part of a diamond is the girdle. The portion below the girdle is known as the pavilion while the portion above it is known as the crown. Only a few customers are aware of the fact that the girdle of a diamond plays a significant role when it comes to measuring the proportions of the stone. When the proportions of a diamond are measured, jewelers compare all other parts of the diamond and compare it with the girdle in terms of size. The result obtained from this comparison determines how well the diamond is cut.