In Mineralogy, a diamond is studied as the second most stable form of carbon; the first being graphite. The superlative physical qualities associated with a diamond are characterized by the covalent bonding between its atoms. This form of carbon is popular for its hardness and thermal conductivity. Cutting and polishing of this element enhances its optical characteristics. There are different types of cuts used to work around the rigid lattice and wide transparency. According to the application, a diamond is cut to attain a clear and colorless appearance, devoid of defects or impurities.
In the original form, diamonds are known to display color variations according to the impurities present in them. While boron content gives the diamond a blue color, nitrogen gives it a yellowish tinge, and lattice defects result in a slightly brown hue. The stone displays a high optical dispersion, and distinct and characteristic luster, that makes it one of the most sought after gems. Diamonds are synonymous with excellent mechanical and optical properties that are further enhanced by the right cuts.
Natural diamonds are ideally mined at depths between 140-190 km in the Earth's mantle region. They are retrieved from carbon-containing minerals, that are formed over billions of years. The ores containing these carbon minerals are usually part of the spewed magma that surfaces during volcanic eruptions. They cool to form igneous kimberlite and lamproite rocks.
Synthetically, diamonds are produced by using a high pressure and temperature, and exposure to chemical vapor. Synthetic diamond variants such as the cubic zirconia and silicon carbide are created to replicate appearance and properties of real diamonds. A cut is done to shape a diamond, prior to polishing the stone. There are a number of cuts adopted to make jewelry with diamonds, such as:
Hearts and Arrows: This cut refers to the distinct visual effect achieved via perfect symmetry. The cut involves the processing of angles and patterns in the shape of hearts and arrows.
Virtual Fancy: This cut is achieved via modern techniques, to attain two stones from an octahedron crystal or macles from irregularly shaped gemstones. The choice of a particular virtual fancy cut is highly influenced by the current trend in jewelry designing.
Modified Brilliants: This cut is similar to the virtual fancy cut. It involves shaping of specific facet counts and arrangements to highlight brilliance and fire interplay. A modified brilliant diamond cut could be 'marquise' or 'navette', 'trilliant', 'heart shaped', 'oval', or the popular 'pear drop' cut.
Step Cut: This cut is usually adopted to shape and polish, square or rectangular diamonds that display rectilinear and/or arranged parallel facets. These cuts are also referred to as 'trap cuts' since their corners are truncated and polished to flaunt an octagonal outline. The step cut is preferred to accentuate a diamond's clarity and luster.
Mixed Cut: 'Mixed cuts' are adopted to maintain the original weight of the gemstone and its dimensions. Also referred to as the 'brilliant cut' and the 'pavilion cut', a mixed cut is commercially extremely popular, due to its characteristic cross pattern and crescent-shaped facets.
These popular diamond cuts have other counterparts such as:
- Radiant cut, has 70 facets, with distinctively trimmed edges.
- Princess cut, has 57 or 76 facets applied to round brilliants.
- Flanders cut, is modified with square-cut corners and facets.
- Rose cut has a flat base, no pavilion, and a triangular faceted crown.
A diamond cut is graded according to the measurements of the pavilion and crown angles. It takes a trained eye to judge its quality. Cut grades need to follow the dictates of standardized table ratio and length of lower girdle facets. Diamond cutting is an art that transforms the rough stone into a faceted spectacle. The cutting process involves extensive cleaving and polishing, beyond planning and consistent monitoring.