The perception of a gemstone's "sides" is a concept that bridges the gap between pure geometry, mineralogical crystallography, and the art of lapidary. In the context of the gemstone trade, the term "sides" is frequently used colloquially to refer to facets—the polished, flat surfaces cut into a rough stone to maximize light performance. However, the underlying raw material possesses a natural crystalline structure defined by specific geometric laws. To understand how many sides a gemstone has, one must distinguish between the natural crystal habit of the raw mineral and the artificial facets created by the cutter. A round brilliant diamond, the industry standard, possesses 57 or 58 facets, while other cuts like the Princess or Emerald cut exhibit different counts ranging from 49 to 144 facets. These numbers are not arbitrary; they are the result of precise mathematical calculations designed to optimize the reflection, refraction, and dispersion of light.
The confusion often arises from the conflation of 2D geometric shapes with 3D gemological objects. A two-dimensional "diamond" shape in geometry is a rhombus, a quadrilateral with four equal sides and four angles totaling 360 degrees. In a regular rhombus, if the angles are 90 degrees, the shape becomes a square. However, a gemstone is a three-dimensional object. When discussing the "sides" of a cut gemstone, we are almost exclusively discussing its facets. A standard round brilliant diamond is composed of a specific arrangement of these flat surfaces. This structure includes a large top facet known as the table, which acts as a window into the stone's interior. Below the table is the crown, which contains the bezel facets and the upper girdle facets. The girdle is the widest part of the stone where the crown and the pavilion meet. The pavilion is the bottom section that tapers down to the point, often terminating in a small facet called the culet to prevent chipping. The sum of these individual planes constitutes the total side count of the finished gem.
The Anatomy of a Cut Diamond: Facet Distribution and Light Performance
The architecture of a cut diamond is a marvel of optical engineering. The number of facets is not merely an aesthetic choice but a functional necessity for light performance. The standard round brilliant cut, which is renowned for its exceptional sparkle, is constructed with a precise arrangement of 57 or 58 facets. This count includes one large table facet, eight bezel facets on the crown, 16 upper girdle facets (often called star and kite facets in specific nomenclature), 16 lower girdle facets on the pavilion (known as pavilion mains), and a single culet facet at the very bottom. The inclusion or exclusion of the culet determines whether the count is 57 or 58.
Each of these facets serves as a prism. The art of cutting involves arranging these planes to ensure that light entering the stone is reflected internally and then exits through the table. The angle and polish of each facet are critical. If the angles are incorrect, light leaks out the bottom of the stone rather than reflecting back to the viewer's eye, diminishing the brilliance. The girdle, acting as the widest circumference of the diamond, separates the crown from the pavilion. The facets on the girdle are the "upper girdle facets" and "lower girdle facets" which are essential for the geometric symmetry of the stone.
Different cutting styles result in varying facet counts. The Princess cut, a popular square or rectangular shape, can range from 58 to 144 facets, depending on the specific execution. The Emerald cut, known for its stepped appearance, typically features around 49 facets. The Ashoka cut, another variant, can possess up to 62 facets. The variation in facet count directly influences the visual character of the gem. More facets generally enhance the sparkle and vibrancy by creating more opportunities for light reflection and refraction. The "little incisions" or facets operate as prisms that refract light and bounce it around the stone to produce the characteristic flashes and sparkles. The precision of these cuts significantly boosts the diamond's worth, as the quality of the cut is one of the "4 Cs" (Cut, Color, Clarity, Carat) that determine value.
The distinction between shape and cut is fundamental. Shape refers to the geometric form visible from the top view of the diamond, such as round, oval, princess, or emerald. Cut refers to the quality of the angles and the arrangement of facets. A round brilliant shape has a specific facet arrangement, while a fancy cut shape like the princess or emerald cut utilizes different facet geometries. The crown is the upper section responsible for the diamond's overall shape, while the pavilion is the bottom section that tapers to the point. The table is the flat top facet, providing the primary window into the stone's interior.
Natural Crystal Systems and the Geometry of Rough Stones
Before a gemstone is cut, it exists as a rough crystal, governed by the laws of mineralogy and crystallography. The natural "sides" of a crystal are defined by its crystal system, which is determined by the internal atomic lattice structure. There are six major crystal systems, each with distinct geometric properties regarding side lengths and angles. Understanding these systems is crucial for the lapidary, as the natural habit of the crystal dictates how it will be cut to maximize yield and beauty.
The Cubic system, also known as the isometric system, is characterized by three equal axes at right angles to one another. In this system, all angles are 90 degrees, and all sides are of equal length. This symmetry is often seen in minerals like diamond in its natural form. The Hexagonal system introduces an additional axis, resulting in crystals that typically exhibit a six-sided prism shape. In the hexagonal system, three axes are equal in length and meet at 60 degrees to each other, while the vertical C-axis is at 90 degrees to the shorter axes. This system yields crystals with six sides.
The Trigonal subsystem is sometimes treated as a distinct category, particularly for minerals like corundum (ruby and sapphire). In this system, the crystals often exhibit a rhombohedral form. The rhombohedral system can be visualized as the cubic system stretched along a body diagonal. The mathematical definition involves three equal axes (a = b = c) with angles that are not equal to 90 degrees (α = β = γ ≠ 90°). A pure simple crystal in this system has six sides.
The Orthorhombic system features three unequal axes that are all at right angles to each other. Here, no sides are equal, and all angles are 90 degrees. The Tetragonal system consists of two axes of equal length at right angles to a third axis of a different length. The Monoclinic system is defined by two angles of 90 degrees and one angle greater than 90 degrees, with no sides being equal. The Triclinic system is the most asymmetric, with no angles equal to 90 degrees and no sides of equal length.
It is important to note that not all gem materials form crystals in these systems. Amorphous materials, such as amber, glass (including obsidian), ivory, jet, moldavite, and opal, are not minerals in the strict sense because they lack a uniform crystal structure. These materials do not form in any of the six crystal systems. Additionally, some materials are polycrystalline, meaning they contain many small crystals but do not have a uniform crystal structure themselves. Beryl, the parent material for emeralds and aquamarine, is a classic example of a hexagonal crystal, though it may not have a set amount of sides in every occurrence, as the crystal habit can vary. Amethyst, a violet variety of quartz (SiO2), crystallizes in the rhombohedral (trigonal) system.
Distinguishing Geometric Definitions from Gemological Reality
A significant source of confusion lies in the difference between a two-dimensional geometric figure and a three-dimensional gemstone. In strict Euclidean geometry, a "diamond" is a 2D rhombus. This shape has four sides, four angles totaling 360 degrees. In a regular rhombus, if all angles are 90 degrees, the shape is a square. However, when a gemologist or jeweler speaks of "sides," they are referring to the three-dimensional facets of a cut stone.
There are several misconceptions found in general discussions. For instance, some sources erroneously claim a baseball diamond has 144 different sides, which is a non-geometric usage of the term. Others confuse the number of vertices and sides in various polygons. A square has four sides, while a hexagon has six. A regular nonagon has nine equal sides and nine equal angles. A rectangle has two pairs of equal sides. The concept of "sides" in a gemstone is almost exclusively synonymous with "facets."
The distinction between shape and cut is vital. Shape is the outline of the stone viewed from above, while cut is the quality of the angles and facet arrangement. For example, a round brilliant diamond has a circular shape, but its "sides" are the 57 or 58 facets. A fancy cut, such as the Princess cut, has a square or rectangular shape but a different facet configuration. The number of facets impacts the diamond's appearance. More facets generally enhance sparkle and vibrancy, while fewer facets, as in an emerald cut, emphasize clarity and the internal beauty of the stone.
In the context of rough stones, the "sides" are the natural faces of the crystal. Amethyst crystals, being rhombohedral, have six sides in their pure simple form. However, the natural crystal habit can vary. Beryl does not have a set amount of sides, as its crystal form can be variable. The hexagonal system yields crystals with six sides, while the trigonal system can produce crystals with different geometries. The key is that the natural crystal system dictates the raw material's geometry, which the cutter must navigate to produce the final gem.
Comparative Analysis of Crystal Systems and Facet Counts
To synthesize the complex data regarding crystal systems and cut facets, the following tables provide a structured comparison. The first table details the geometric properties of the major crystal systems, highlighting the relationship between axes, angles, and the resulting number of sides in their natural state.
Table 1: Geometric Properties of Major Crystal Systems
| Crystal System | Axis Relationships | Angle Relationships | Typical Number of Sides (Natural Habit) | Common Gem Examples |
|---|---|---|---|---|
| Cubic | 3 equal axes (a=b=c) | All angles 90° | 6 (simple form) | Diamond, Spinel, Garnet |
| Hexagonal | 3 equal horizontal axes, 1 vertical | Horizontal axes at 60°, vertical at 90° | 6 | Beryl, Tourmaline |
| Trigonal | 3 equal axes | All angles equal but not 90° | 6 | Amethyst (Quartz), Corundum |
| Orthorhombic | 3 unequal axes | All angles 90° | Variable | Topaz, Zircon |
| Tetragonal | 2 equal, 1 unequal axis | All angles 90° | Variable | Zircon, Scapolite |
| Monoclinic | 3 unequal axes | Two angles 90°, one >90° | Variable | Jade, Emerald |
| Triclinic | 3 unequal axes | No angles equal | Variable | Kyanite |
Note: The "Typical Number of Sides" refers to the natural crystal habit. Not all crystals in these systems will have exactly that number of sides in every instance, as crystal growth can be irregular.
Table 2: Facet Counts for Common Diamond Cuts
| Diamond Cut | Approximate Facet Count | Description of Facet Arrangement |
|---|---|---|
| Round Brilliant | 57 or 58 | 1 Table, 8 Bezel, 16 Upper Girdle, 16 Lower Girdle, 1 Culet (optional) |
| Princess Cut | 58 to 144 | Square/rectangular shape, high facet count for maximum sparkle |
| Emerald Cut | ~49 | Stepped facets, fewer facets, emphasizes clarity and color |
| Ashoka Cut | Up to 62 | Variations in standard brilliant cut |
The data indicates that the facet count is a deliberate design choice. The round brilliant cut is the standard against which others are measured. The Princess cut, with its potential to have up to 144 facets, utilizes a high density of facets to maximize fire and brilliance. The Emerald cut, with its stepped design and approximately 49 facets, prioritizes the clarity and the "hall of mirrors" effect over the intense sparkle of a brilliant cut. The culet is a critical component; its presence or absence shifts the count from 57 to 58.
The Role of the Cutter: Transforming Rough Geometry into Faceted Beauty
The transformation from rough crystal to finished gem is a process of synthesis. The cutter must analyze the natural crystal habit to determine the best orientation for the cut. For example, a hexagonal crystal like beryl has six natural sides, but the cutter will remove these natural faces to create the new facets required for the final shape. The scratches on a beaker in a crystal growing experiment promote nucleation and crystal growth, but in the lapidary, the cutter creates new planes to optimize light performance.
The "sides" of the final gem are the facets. These facets are not random; they are mathematically calculated to act as prisms. The table facet is the largest and serves as the main window. The crown and pavilion facets are angled to reflect light internally. The girdle acts as the boundary between these two sections. The culet prevents chipping at the tip. The precision of these cuts determines the diamond's value.
The natural crystal system of a gem dictates the starting material. Amethyst (SiO2) has a rhombohedral form with six sides. Diamond, in its natural state, belongs to the cubic system, often appearing as an octahedron with 8 faces in nature, though this is distinct from the 58 facets of the cut stone. The confusion between natural faces and cut facets is common. A baseball diamond is not a gemstone; it is a sports field shape.
The art of cutting is to transform the rough stone's natural geometry into a symmetrical, optically perfect object. The facets operate as prisms, refracting light and bouncing it to create brilliance. The number of facets varies by cut. The round brilliant is the benchmark. Fancy cuts like the Princess or Emerald have different counts. The more facets, the more sparkle, but the fewer facets, the more emphasis on clarity and color.
Conclusion
The question of "how many sides a gemstone has" requires a dual perspective: the natural geometry of the raw crystal and the engineered geometry of the cut gem. In the realm of natural mineralogy, the number of sides is dictated by the crystal system, with hexagonal systems typically yielding six-sided prisms and trigonal systems producing rhombohedral forms with six sides. In the realm of lapidary, the "sides" are the facets, the polished surfaces cut into the stone. A standard round brilliant diamond possesses 57 or 58 facets, a number that has been optimized over centuries to maximize light reflection. Other cuts, such as the Princess cut, can range from 58 to 144 facets, while the Emerald cut utilizes approximately 49 facets. These variations are not arbitrary but are strategic choices to enhance the stone's fire, brilliance, and overall aesthetic appeal. Understanding the distinction between the natural crystal habit and the artificial facet count is essential for any serious student of gemology. The "sides" of a gemstone are a testament to the intersection of geological law and human craftsmanship.