The symmetry of a diamond refers to the precision and the exactness of shape with which the various facets in a diamond are aligned and interset. Even though symmetry plays a much important role in low-grade diamonds, they are very important in high clarity graded diamonds.
In an ideal cut diamond, the Girdle of a diamond should be a flat plane, parallel to the table. A wavy girdle is when the girdle “waves” as it wraps around the diamond.
Crown & Pavilion Misalignment
A well-proportioned Round Brilliant diamond, the top of the pavilion mains and the bottom points of the bezel facets should meet precisely at the Girdle. If the diamond’s crown and the pavilion is misaligned then it is labelled as asymmetry flaw.
The extra facets are man-made flaws on a diamond. Typically, the extra facets are found near the girdle or pavilion.
In order to check whether the culet is centred or not, place the diamond in the face-up position. Look through the Table if the lines formed by the lower girdle facets look like a perfect square. If the shape you see is a perfect square then the Culet is centred. If the cross bends in one way of the other, then that means the culet is off-centred.
The Table (the largest facet on a diamond) should be always placed at the centre-top of the diamond, parallel to the Girdle. An off-centred Table can cause uneven crown angles from one side to the other.
Table & Girdle Not Parallel
If the Table and Girdle are not parallel to each other, the Crown angle will be much steeper than the other.
An ideal-cut diamond displays a regular octagon-shaped Table with eight sides of equal length that run parallel to the opposing opposite facet. A misshapen face is when the facets are not properly shaped or they are not of the same size and shape as others.
Faces Not Pointing Up
Facet patterns of a diamond are meant to show a precise arrangement of perfectly shaped facets. However, some diamonds display facets that are not properly pointed.
Naturals on Crown and Pavilion
The original ‘rough’ of the diamond is meant by Natural. Naturals always start or occur out on the Girdle. They either dip towards the Crown or the Pavilion.