Gemstone & Jewelry Terminology

In addition to the most typical shapes and cuts of emeralds like round, oval, and cushion, there are plenty of other types of cuts. Many of these come in and out of style depending on whether the gems are carved, cut cabochon, or faceted based on what grade of gem material they are.

J8890 | medium | play

A Zambian cabochon emerald set into a three-stone diamond halo ring

Cutting & Polishing Capabilities

In antiquity, the tools and skills of lapidaries were limited. The first type of “cut” was to polish exceptionally well colored and clear gems in the original shape they grew in. This is referred to as a gem’s growth habit, with different gems preferring to grow in different shapes. For instance, emeralds prefer to grow as a hexagonal prism.

Eventually this type of “cutting” evolved into what we know today as cabochon cuts, though modern cabochons are cut into highly regular shapes. They can also come in forms other than ovals and circles, like pears and sugarloaf, though they typically stick to the basic shapes.

Qualifying Cabochons

Aside from the highly regular cabochon shapes shown above, rough emerald crystals with a basic polish qualify as cabochons as well. In the case of this Egyptian necklace, these cabochon shapes have been drilled and made into beads.

It is also possible to tell that a number of the beads are emeralds. Many of them are in a hexagonal shape, which is the shape emeralds’ prefer to form in, or their growth habit.

Evolution of Faceting

As lapidaries became more familiar with gems and faceting them, a myriad of cuts were developed.

1 and 4 are top and profile diagrams for an earlier form of the round-brilliant cut.

2 is an oval cut.

Cuts 3 and 6 are top and profile diagrams of a “rose” cut, similar to the cabochon cut 12. The cut is raised and has a flat bottom.

5 is a cushion cut. 8 is more of a teardrop than a pear shape due to how the point curves, but still qualifies as a pear shape.

9 is what is referred to as a “baguette” cut, which is still widely used for side-stones today.

7 is an emerald cut, which is derived from the shape of the baguette cut. The only significant difference between the two is that the emerald cut has its corners cut off.

10, 11, and 12 are all examples of cabochon cuts. So long as there is a domed surface, a gem qualifies as a cabochon cut.

Note that these cuts are mainly for diamonds. The main cut used on emeralds, historically speaking, is an emerald cut or some variation of it like the asscher or octagon. This cut was designed to be particularly gentle on emeralds since they are usually brittle, and could be broken on the cutting wheel otherwise. This was also the most durable cut for them. With current cutting equipment and technology however, this is no longer a problem.

Cutting for Phenomena & Trapiche

Aside from the stylistic choice of a cabochon cut, it is the only way to display certain phenomena in gems. There are a wide range of phenomena, but the only one that occurs in emeralds with any regularity is a cat’s eye . The only way to display this is with a curved surface, hence the cabochon cut.

Individual Facets

The individual facets of a gemstone all have their own name, but there are notable differences between diamonds and emeralds. These differences apply to diamonds and other colored gems too.

E1587 | medium | play | “Emerald ID: E1587 – Weight: 1.16 Carats – Origin: Zambia”

Most cuts are designed for diamonds, not colored gems. The diagram above is noted as being for a diamond cut. The main difference between a typical diamond cut and colored gemstone cut is that the pavilion of a colored gemstone is typically done with a type of modified step cut . This is because colored gems do not receive brilliance from their cut the way diamonds do, and these step cuts conserve the carat weight of the gem.

Brilliance

Brilliance is the number one consideration when a lapidary facets a gemstone. Brilliance comes from light passing through a gemstone and reflecting back to the viewer. It’s the shiny, colorful light gemstones produce, essentially the gem’s color.

Things a lapidary wants to avoid in a gem are windowing and extinction. Windowing means the viewer can see straight through the gem, and extinction refers to the black areas where the light does not return to the viewer. These factors in combination with brilliance are directly influenced by the cut. Ideally a gem would have 100% brilliance and 0% extinction and windowing, but this is impossible to achieve even with a perfect cut. The very best brilliance typically expected in colored gems is 75%.

Types of Settings

There are many, many types of settings, and a few different methods of making them too. There are also designer settings that do not fit into existing categories.

There are many, many types of settings, and a few different methods of making them. There are also designer settings that do not fit into existing categories.

Bezel Set Emerald

J8988 | medium | “Emerald Jewelry ID: J8988”

A bezel setting is when the setting is wrapped around the gemstone completely. This is not to be confused with a gypsy or flush setting where the gem is physically embedded in the metal.

Prong settings are very common, and very simple. All that holds the gem in its setting is a set of prongs. A pave setting is not a specific type of setting, but a broad category consisting of any jewelry made with numerous small gems. By definition a halo setting with lots of small gems around a center gem is also a pave setting.

A channel setting is when gems are placed in a grooved channel so there are no visible borders between gems. Invisible settings are similar, but have the gems suspended on a framework that remains invisible from the top of the setting. They are also very intricate and complicated to make for this reason. Lastly for more common settings is the tension setting. As the name implies, the gem is held in place by tension

Channel Set Emeralds

Tension Setting

Jewelry Manufacturing

Precious metals are made into jewelry by employing four common methods: die striking, wax casting, electroforming, and hand fabrication. In the same way that settings are not necessarily restricted to one group and can encompass different labels, jewelry designers and setters often use different methods of manufacturing in order to complete their designs.

An old and durable method of jewelry manufacturing is die striking. This process is quick, cost effective, and produces durable settings. This makes them popular for prong settings since the prongs can be small and delicate. There are two main components to this process: a mold and a die. After being fed a metal “blank” for the setting, the die strikes the blank into the mold and makes the setting.

Wax casting is another very old method. It is not as durable as die striking, but enables the creation of lots of delicate details. The modern version of this process is also great for mass-production.

The current process involves making a wax model in a rubber mold. Identical wax models are then attached to a wax “tree” and covered with a plaster-like material, called investment.  Once the investment has dried, it is heated and melted wax is drained from the mold.  The hollow space left behind is then filled with molten metal, which is allowed to solidify.  When the investment is removed, the result is a precious metal “tree” of castings. The castings are clipped from the trees, cleaned, and polished.

Electroforming is a technique that uses electricity to deposit metal over a model. Electroformed jewelry is not as durable and is more difficult to repair than jewelry produced by other means, but the pieces are lightweight and often intricately detailed. In this technique, a wax model is attached to a frame and submerged in a special chemical bath. An electrical current gives the models a positive charge, which attracts negatively charged particles of precious metal. When the metal layer is thick enough, the wax model is melted away, and a hollow piece of precious metal jewelry is created.

Lastly there are hand-fabricated jewelry pieces. These are the most time-consuming and laborious types of jewelry to make. This can utilize any number of techniques such as sawing, carving, hammering, soldering, setting, etc, but the end product is something only possible with craftsmanship. Hand-made is also an accurate term, though the professional term is hand-fabricated.

Loupe

A 10x lens, a loupe, is one of the most convenient and useful of all instruments for gemological observation and identification. Loupes will fit in any pocket, can cost as little as $10, and provides invaluable information about the gem you are looking at.

10x magnification is the standard of any gemological grading, however colored gems are only graded at what is eye-visible. The magnification is meant for identifying inclusions, and other clarity characteristics. Higher magnification is possible, but at that point you need a microscope.

Use

To use a loupe, the lens needs to be roughly 1 inch from your eye. Adjusting the distance between the eye and loupe is fine. You can also wear glasses while using it, though it might be easier without them.

Make sure that you have adequate lighting when looking at the gem. Otherwise you won’t be able to see anything. The most popular technique is to have a light source coming from the side, while viewing the gem against a black background.