Faceted Stone Terminology
Cabochons – In the distant past, most sapphires were fashioned into cabochons. This ancient cut features a curved upper surface with a flat or curved underside. The upper portion of a cabochon may be a simple dome or a series of curved surfaces that meet in a pyramidal arrangement (e.g., a sugarloaf cabochon). A cabochon may be any shape, but circles and ovals appear most often. Star sapphires are cut into domed cabochons to display their special phenomena.
Faceted Cuts – The advent of improved gem cutting technologies enabled lapidaries to facet gemstones. Facets are the flat, polished surfaces of a finished gemstone. In the early days of gem cutting, many stones were table cut, which created a single polished face on the top of the stone.
Rose Cut – Later, rose cuts became popular. A rose cut stone typically has a flat bottom and radiating triangular facets that come to a point at the top of the stone.Today, we use three key cutting styles to create faceted stones: brilliant cuts, step cuts, and mixed cuts.
The Round Brilliant – The most traditional cut seen today usually in a shape that is round,this diagram below identifies the various facets of a typical round brilliant cut with 58 facets. The girdle is the narrow edge around the part of the stone with the widest diameter. It separates the gemstone’s crown and pavilion. The tiny facet at the very bottom of the stone is called a culet. Culets can vary in size, but they are usually very small. Sometimes the point of the stone is called a culet even if the stonecutter created no additional facet.
Step Cut – Step cuts consist of parallel facets. Examples of step cuts include the square step cut and the emerald cut. Larger sapphires are rarely given brilliant cuts. While the facets of a brilliant cut create a lively play of color, the geometry of the brilliant cut is a poor match for most sapphire crystals because it creates a large amount of wasted rough. The parallel arrangement of step cut facets allows cutters to adjust the finished stone’s proportions to the shape of the rough crystal.Step cut sapphires may not sparkle like those with brilliant cuts, but in exchange they offer broad, uninterrupted expanses of color. Step cuts are usually reserved for highly transparent sapphire rough with outstanding color. While the glitter of a brilliant cut can obscure unsightly inclusions, a step cut will only emphasize the shortcomings of a lesser stone.
Mixed Cut – The most common sapphire faceting style is actually the mixed cut, which combines a brilliant cut crown with a step cut pavilion. An example of a mixed cut is the oval mixed cut. Mixed cuts offer significant advantages over brilliant cuts and step cuts. The crown of mixed cuts is brilliant cut to maximize the brilliance and sparkle of the stone and to obscure minor clarity issues. The pavilion is step cut to save weight and bring out the color of the stone.One of the newer cuts for sapphires is a radiant cut, which is a rectangular mixed cut with a step cut crown and brilliant cut pavilion.
A Note On Brilliance
Brilliance describes the amount of light that a sapphire reflects back to the viewer from the interior of the stone. Brilliance is a consequence of cut, and it is an important characteristic because it determines the perceived liveliness and color of a gemstone.
To understand brilliance, we need to follow the path light takes as it travels through a faceted sapphire. White light entering a sapphire from above travels through the gem in a straight line. As it does so, some of the component colors of the visible spectrum are absorbed. The spectral colors that are not absorbed determine the stone’s color. For example, a yellow sapphire will absorb red, orange, blue, violet, and green portions of the visible spectrum, leaving mostly yellow to be reflected back to the eye of the viewer.
When light passing through the crown reaches the rear or pavilion, it can either travel right out through the bottom of the sapphire or reflect back into the stone, depending upon the angle at which it strikes the facet. If light passes straight through the stone, it won’t return any brilliance to the viewer. Light that reflects off of the pavilion facets and then exits the stone through another part of the pavilion doesn’t return any brilliance to the viewer either. Only those light rays that reflect back out through the crown toward the eye of the viewer provide brightness and color. These rays account for a sapphire’s brilliance.
To evaluate brilliance in a cut sapphire, hold the stone level under overhead light and look directly down at the crown. You might notice some very pale or weakly colored areas. If so, you are looking through what jewelers and gemologists call a “window” in the stone. A window is an area where light passes all the way through a cut stone without being reflected back to the eye of the viewer. Even the most carefully cut sapphire will show windows at certain angles, but windowing should be minimal, or completely absent when a stone is viewed from directly above. You may also see that some parts of the stone look very dark – maybe even black. These dark areas are called “extinction” areas, and they occur when light leaches out of the sides of the pavilion, rather than returning to the viewer. Many natural sapphire crystals have broad, flat, tabular shapes. In order to conserve weight, these stones are often cut with very shallow pavilions and broad crowns. Light entering the crown passes right through the flat pavilions of these shallow cut stones creating a pale, unsaturated window. Other sapphires occur as long, bipyramidal crystals. These sapphires, if cut to conserve weight, may have deep pavilions, which can occasionally cause extinction effects. A gem’s brilliance is measured as the percentage of its face-up area that shows neither extinction nor windowing when lit and viewed from above. A sapphire that has no windowing or extinction over:
- 75 percent or more of its surface shows “excellent” brilliance
- 60-75 percent is “very good”
- 40-60 percent is “good”
- 25-40 percent is “fair”
- < 25 percent is “poor”
Sapphires with “excellent” brilliance are hard to come by, because the requisite cut angles and proportions can require much of the rough sapphire crystal to be ground away. “Good” to “very good” brilliance is easier to attain without wasting significant rough.
Drawings & Renderings
Custom-made jewelry takes vision, skill, and experience. A design is first discussed with the aid of existing pictures or an already completed piece of jewelry. Rough sketches are then made to complete the model design.
Wax Model – A wax model of the mounting is created that will be used in the metal casting process. The model is created to the exact specifications of the stones being used. Fine wax models take considerable time and expertise. The model quality and design is very important since the finished piece will be an exact replica of the wax design.
A mounting is the cast metal form of a piece of jewelry. Mountings include rings, earrings, necklaces, pendants, brooches, and cuff-links. Once the center stone has been selected it is then added to the mounting (or “semi-mount”). Mountings can have side stones or pave diamonds already set within it.
There are many different methods of setting stones in jewelry. The most common and widely used methods are: Prong: Prong setting is the most traditional and classic technique of setting a stone into jewelry. Although a prong setting is simple in method and design, a good setting is the finishing touch to a piece of jewelry. Traditionally, prong settings have 3, 4, or 6 small metal claws or prongs that secure the gemstone within the setting. The small claws are bent over the top of the gemstone to hold it in place and can have decorative shapes or designs. Common prong shapes are round, square and v-shapes.
Double Prong: A double prong setting is most often used with very large stones that require extra security and support. However, a double prong setting is sometimes requested as a special design element for smaller stones as it lends a unique look to the jewelry piece.
Claw Prong: A claw prong is a unique way of finishing the prongs in a setting. Rather than a round, square, or v-shape prong, claw prongs taper to a point. Claw prongs can lend a refined appearance to an item of jewelry. Double claw prongs can be crafted for larger gemstones.
Bezel: Bezel settings are created by wrapping a thin metal band around a gemstone’s perimeter. Bezel settings are extremely secure and safely hold the gemstone in place.
Channel Setting: Channel setting is a technique where gemstones are set next to each other in a row within a u-shaped track or channel of metal. Channel set jewelry is very durable as the edges of the gemstones are not exposed to wear. Channel setting is often found on wedding bands and eternity bands.
Pave: Pavé is a specialty setting style where small round stones (usually diamonds) are set very close together.There are many methods to create this style of setting. Pave settings are normally done by hand with a special tool called a “graver.” A bead of metal is created by raising areas between pre-drilled holes. These small beads are then used to hold the stones together in a close and uniform way. The finished look is clean and elegant.
Micro Pave: Micro Pavé is very similar to Pavé except extremely small stones are used (in some cases, less than 1 mm each). This work is often done with the aid of a microscope and sometimes laser tools for ultra-fine finishing. This type of setting work is completed by a specialist and can be very expensive and labor intensive.
Rings & Bands
Rings: Rings are composed of two separate parts: the shank or the band, and the head or the crown. Most rings have a simple circular band of metal for the shank, but there are other, more intricate designs. A shank that does not have a universal width around the entire finger would be considered a tapered shank. This is a decorative element but also can make the ring slightly more comfortable to wear if the taper is at the bottom of the ring. A split shank is a shank with two separate bands of metal creating the shank.
The two pieces of metal join on the underside of the band. Split shanks are usually found on rings with large gemstones as they help support the weight of the stone.
Bands: A band in its simplest form is a single piece of metal wrapped around the finger. There are varying designs for bands that can range from plain metal to multiple inset gemstones.Many plain band rings, especially men’s rings, will have a comfort fit design. Comfort fit rings have a smooth curve on the inside of the band to make the ring more comfortable to wear.
The head or the crown of the ring is the piece of metal that will hold the gemstone. There are varying designs for the crown or head. A few popular styles are listed below:
Solitaire Ring: A solitaire ring is a very classic ring style. Often seen for engagement rings, solitaire rings feature a band with a single gemstone set above the band in a prong setting. In some modern styles, a solitaire can feature a band with the central gemstone set into a bezel setting rather than a prong setting, but the idea of the solitaire remains the same. Solitaire rings are meant to highlight and feature a single gemstone.
Three-Stone Ring: Three-stone rings are another classical style and are extremely popular for sapphires and other colored gemstones.
A three-stone ring features three gemstones: a central main stone and two matched side stones or accent stones. The accent stones flank the center stone on each side.
Cocktail Ring: A cocktail ring is a large or over-sized ring, often featuring precious or semiprecious stones. Cocktail rings became popular during the 1950s and ’60s and have continued to be a staple fashion accessory.
Originally worn on the ring finger of the right hand, cocktail rings are sometimes called “right hand rings,” but the term “right hand ring” can also apply to any ring worn on the right hand, regardless of size.
Bracelets are usually 7 inches long. We can create special lengths for custom orders. Bracelets can be created with a flexible metal chain that allows gemstones to be set within.
There are other, non flexible bracelet options including a cuff or a bangle. Cuffs are usually wide bracelets while bangles are usually thinner and many are worn at once.
Necklaces & Pendants
Most of our necklaces and pendants come with a standard 16” link chain. 18” chains or specific chain styles can be purchased by request.
Collar: Made to fit the neck – usually 12-13 inches (30-33 cm).
Choker: 14-16 inches (36-40 cm).
Princess: 17-19 inches (43-48 cm).
Matinee: 20-24 inches (51-61 cm).
Opera: 30-36 inches (76-92 cm).
Rope: Over 36 inches (91 cm or more)
Retailers have seen the resurgence of men’s jewelry within the past few years. While cuff-links have always held strong in the market, men’s rings, tie tacks and pins have become popular items as well.
The Natural Sapphire Company conducts three non-destructive tests on many of the sapphires in our inventory. The insights gained from these analyses serve several purposes. These tests provide information unique to your gemstone, which can be used for identification purposes in the future. They also distinguish your natural gemstone from a man-made one. In addition, these tests help to determine the provenance, or origin, of your sapphire and the presence or absence of gem treatments or enhancements. UV-Visible-NIR Spectrum
In this test, a spectrophotometer is used to analyze electromagnetic energy from the ultraviolet, visible, and near-infrared part of the spectrum. This instrument compares the intensity of this light after it passes through your gemstone to the intensity of the light before it passes through your gemstone. The results can be used to identify different components in your gemstone (often atoms of metal elements) since each has its own unique absorbance peak in the spectrum. The information gained from this test is complemented by the information provided by fluorescent spectroscopy.
EDXRF Trace Element Chemistry Energy Dispersive X-Ray Fluorescence is used to obtain a chemical characterization of your gemstone. Among other things, this test indicates the type and concentration of metallic trace elements present in your gem. This is important information because trace elements are responsible for the color of your gemstone. During this test, your gemstone is bombarded with energy, which excites elements in the crystal lattice causing them to give off X-rays, which reveal their identity. Although this sounds harsh, the test is non-destructive, which means your gemstone is not altered or harmed in any way.
FTIR Spectrum Fourier-Transform Infrared spectroscopy is used to identify chemical compounds and substituent groups. In this test, infrared radiation is passed through your gemstone where some of it is absorbed and some transmitted. The resulting spectrum is like a fingerprint: it identifies the nature of your gemstone because peaks at certain wavelengths are diagnostic for specific materials. No two compounds produce the exact same infrared spectrum, so it is a means of positively identifying your gemstone as an untreated sapphire.
Learn how to take care of your fine sapphire jewelry in, Sapphire Jewelry Care.