Gemstone Cutting

by Sheweta Dhanuka

Gemstones in the jewelry items enhance beauty of the women making her more attractive and splendid. Gem makes women beautiful and gem cutter makes gems beautiful. When woman is seen wearing the gemstone jewelries it is in it’s finest form but initially as rough any precious or semi precious stone is as simple and pale as a normal pebble. It achieves it magnificent look after it undergoes the gemstone processing. This process is known as Gem Cutting or Lapidary that involves cutting and polishing. An individual performing this art on the stone is known as gem cutter or lapidarist.

These amazing gemstones are created deep under the earth crust by the grace of Mother Nature. Innumerable chemical reactions take place in varied weather conditions like high temperature, pressure etc and then stones are retrieved after difficult mining. The material procured as the result of mining is referred as rough. The rough undergoes gem-cutting process in order to get transformed into small stones so that it becomes wearable and useful for other purpose.

Gem cutting is a long process that takes many months to convert simple rough into fascinating gemstone. It involves many steps. In order to acquaint the reader with the overall process of gem cutting, all the steps are explained one after the other. The steps elucidated are not in any fixed sequence. The reason being, it is not necessary that each single stone would go through all the mentioned steps like for example precious stone diamond is hardly ever seen in form of beads so for this gem drilling step makes no difference. Similarly, for gemstone comprising infinitesimal inclusions, two almost same steps like grinding, sanding gets clubbed into one.

Gem cutting process involves lapidary techniques that convert bleak rough into eye-catching gemstone. The well-defined gems then are used in distinctive ways viz. cabbing, faceting and carving. Be an adjunct with the above-mentioned techniques, the below text also mentions about the different shapes and mixing styles practiced in the gemstone industry.

Lapidary Techniques

These are the first and foremost techniques of this crucial process where rough is lightly hammered to confiscate unwanted part like brittle and fractured area of the stone. It is performed in eight different stages starting from sawing, grinding, sanding, lapping, polishing, drilling and tumbling.

Sawing

As the name specifies, in sawing a saw or cutter is used to convert rough into small stones. The saw is sharp circular blade made up of steel, copper or phosphor bronze alloy and its surface periphery comprises diamond clench. It is infused in the rough and then whirled at many thousand feet for every minute to make the gemstone. After heating in order to remove unwanted material from the stone, it is washed with either with water or oil. Washing helps stone and saw from getting overheated. This entire process requires lots of concentration and expertise, one single mistake can result in severe damage. Therefore, intense precautions are taken while sawing. It is brutal to hold the rough with naked hands while sawing; consequently the person covers hands and face with appropriate safety gadgets.

There are mainly two types of saws viz. circular and jig. According to the rough and the gemstones to be retrieved the saws are selected. Saws are available in different sizes.

Circular Saws

These are the most common saws used by gem cutters as it is suitable for the majority of roughs. The edge of the saw is plane and sharp. There are three different types of circular saws.

Slab Saw

Slab saw consists of 16-24 inches diameter. It is used for cutting thick rough into thin slab stones.

Trim Saw

Trim saw possesses 6-10 inches of diameter. It is used for cutting smaller roughs into small stones.

Faceter’s Trim Saw

This saw has minimum diameter that is of 4 inches, least amongst all. It is used for cutting the most valuable rough into small stones.

Jig Saws

As the name specifies, the edge of the saw is jig jag that is helpful in cutting curved lines in the rough. It is used along with a thin metal band or wire. This saw minimizes the wastage therefore is mostly used for costly stones like Ruby, Emerald, Alexandrite and so on.

Grinding

Once the rough is sawed into small stones then after each single stone is rubbed against either diamond – infused or silicon carbide wheels to bestow the preferred outward appearance. This is referred as preform. At this stage many times the surface of the stone is left with undesirable scratches. Subsequent to grinding the unwanted grits and mesh are removed by cleaning the preform with water or oil. It also acts as coolant as it averts the stones from excessive heat.

Sanding

In this stage the stone gets the flat and smooth surface. Through the use of excellent abrasives, the graze and scratches are removed from the stones that are left behind in the previous step. It is the crucial step for shaping the stone as from now the perfection in final appearance begins.

Lapping

This step of gem cutting process is quite similar to previous two steps that is grinding and sanding. The stones are stroked against one side of either gyratory or vibrating flat disk in order to give the flat surface. The disk is made up steel, cast iron and copper bronze alloy etc. It is known as Lap.

Polishing

It is the most important step as after this step the gemstones attain the mirror like appearance that helps in light reflection from its surface area. Different types of polishing agents are used for defining the overall look of the stone. Alumina, cerium oxide, tin oxide, lead, ferric oxide, chromium oxide and silicon oxide etc are few names of the polishing agents used by the gem cutters. Ferric oxide also known as jeweler’s rouge and silicon oxide called as tripoli are mostly used. According to the surface of the stone the polishing agent is selected for example flat surface stones are polished with tin oxide, lead, pellon or leather. For round surface felt, leather, cork or cloth is used.

Drilling

As the name specifies, in this step a small hole is created through the stone, such stones are known as beads. Only some semi precious stones are used for making the beads as precious stone and other semi precious stones like alexandrite etc are too expensive. Small revolving rod or else tube with a diamond or silicon carbide tip is inserted to drill the hole in the stone. Silicon Carbide consists of 9.5 Mohs while diamond is 10 Mohs on the hardness scale. The former is the synthetic compound of silicon and carbon. This manmade amalgam is used mostly for softer gemstones. Ultrasonic or vibrating drills are the most effective source for drilling the gems but are used exclusively for huge amount of beads, as it turns too costly for making small number.

Tumbling

It is the mode of giving the desirable attractive shape to the stone that are formed roughly in the lap of natural environment. Large numbers of unappealing shaped stone are turned in a tumbling barrel at a dawdling speed along with abrasive silicon carbide and water for days together. Stones are rinsed vigilantly between the grades there by attaining the smooth and polished look. There are two ways for tumbling the gemstones. One is rotating while other is vibrating.

Rotator Tumbler

These are the barrels hexagonal in shape that aids in the rotation of the gems. In rotator tumblers the gems are turned fully upside down. In order to know the progress of the gems inside the tumbler, it has to be brought to a standstill in regular time duration. Rotating tumbler is standard tumbling method and is cost effective too.

Vibratory Tumbler

These barrels are like a container in which the gems are in the stationary position but are vibrated from all sides. It is quite easy to monitor the progress of the gems inside this tumbler as compared to the rotator tumbler.

Faceting

The aim of faceting is to reveal the vividness and luminosity of a gem. It refers to the light refraction in the stone that is when light ray enters from one of the facet of the stone it is reflected back for the bottom facet. The viewer in rainbow colours views this light refraction. Proper faceting is very important for the transparent stones such as diamond, ruby, peridot, sapphire, topaz and many others. Well-created facets in the stone amplify its net value magnificently.

An individual creating the facet is known as facetor. He/she cuts and polishes the facet on the intact surface of stone using the faceting machine. The machine consists of a motor that holds the hand piece assembly by rotating the lap, water supply and adaptable hand piece along with index gears, protractor and mast/platform. There are two types of faceting machines – one is left that is known as mast- type and other is right faceting machine. The later is further having two varieties viz. hand piece and platform.

The flat surface of the gem is known as facet. Each facet on the stone is created in a proportioned pattern. First the facetor immerses the gemstone in the adhesive wax, epoxy or glue and sticks it on a metal dipstick. Later it is placed in the hand piece to get the position control. Then after cutting angle is adjusted vertically with the help of the protractor while rationally it is done through index gear. Finally then facets are created after grinding, sanding and polishing on the revolving lap. In the regular intervals water and other solutions are used as coolant and lubricant respectively. This cycle completes one side of stone. A jig is used to change the side on the dipstick. In the same way by repeating the steps opposite side is finished too. Normally flat facets are seen but with modern technology and innovative ideas of facetors, new-fangled concave facets, grooves and much such novel stuff are created.

Cabbing

It is also known as cabochon cutting, the simplest and most common lapidary form. Opaque and translucent stones are designed in this variety. Transparent stones with too many inclusions are also cut into cabochons to use it optimally. Cabochon at top are smoothly curved and polished while on bottom it is flat or round that could be polished or sanded as per the jeweler’s requirement. Turquoise, opal, bloodstone, lapis lazuli etc are mostly shaped into cabochon.

Cabbing procedure is almost same as faceting. Cabochons or cabs are cut through the process of dopping where the stone is attached to the dipstick with the help of either adhesive wax or glue. Later the stick along with the stone is rotated during all the lapidary techniques to have the smooth rounded surface all over the stone. Dopstick is made up of metal or wood. Separate cabbing machines are also available. These machines consist of quite a lot of wheels having diamond or silicon carbide gravel, twirled by one single arbor and motor. It also has a continuous water supply that acts as a coolant/lubricant to rinse off unwanted fragments and protects the stone from excessive heat.

Carving

It is a creative art in born in the carving artist. It is the most difficult art as the craftsmanship involves deep concentration, patience and imaginative skills. Apart from these talents he/she must also possess methodical knowledge about the lapidary techniques then only they could give astonishing look to their respective artwork. One who carves the costly gems is a skilled individual, turning the plain stone into captivating masterpiece having the functional or decorative use.

Semi precious stones are suitable for carving as precious stones are extremely valuable and pricy. There are many different types of carvings done on the gemstones. Some of the most common ones are :

Cameos

Stones and sea shells are referred as cameos. It is the carved portraits in any size of the stone. The portrait is carved above the surface of the gemstone. It seems striking because of the natural colored layers and remarkable carving. The wonderful blend of God’s creation and human art in one single frame looks amazing. Semi precious stone Agate is most commonly used for making this carving item however; some fine artist also brings other stones into play. Italy and Germany are the main source of premium cameos carved from shell and agate stone respectively across the globe.

Intaglios

This art conception is quite similar to that of cameos. It is carved on gemstones and seashells as well. The difference between the two is of carved portraits. Intaglios are the portraits that are carved down into the surface of the stone while the portraits are raised above the stone surface in cameos. The beauty of the carving emerges due the different coloured layers displayed in the stones through the natural formation. Italy and Germany again are the preeminent foundation of eye-catching art pieces of this form of carved item.

Sculpture

These are the carved forms of living things, it may be any animal, bird or even the human face or body. This is solely created and procured to decorate unusual corners of the dream home. It is mentioned especially for dream home because sculptures are relatively classy and pricey when compared with other carved forms.

It is priced high due to three reasons. First, creating a sculpture requires extreme expertise and artistic skills, as all the organs of the living creature should be well defined. There is no scope for minute errors or slight change else the final look of the art piece differs from the look of the living being. Artists take months to do fine detailing of their masterwork. Second reason is the cost of the raw material. The main raw material for carving sculpture is the stone. The price of the stone itself is very high. Further, the cost increases with the increase in the size of the stone. Moreover, for creating any size of carving the stone turns out to be more costly than the wood or clay. If it is carved on the single stone then the price is increased more. Finally the third reason, additional use of other coloured stones or diamonds to give it more natural look makes the price touch the sky.

Stand Alone Carving

These are the carving pieces that are not used for making jewelry items. They are created for decorative purpose or for some practical use such as ash trays, jewelry boxes, pen stands, key chains, paper weights and so on. These fine-looking objects are always in demand by the gemstone lovers.

Beads

These are engraved as small spheres first and later drilled to make beads that could be string together in a string to make the diverse jewelry items like necklace, earrings and hand bracelets etc. In order to make spheres, the lapidarist saws cubes or dodecahedrons from the rough. The cubes then are shaped into round by grounding it between the rotating concave cutters. The stone revolves around the concave cutter irrespective of the direction and attains the desired spherical shape. The spheres formed, then undergo the lapidary process of grinding, sanding and polishing. Finally, these are drilled to form the beads.

Once the beads are formed, it is taken over to bead mills for grinding and sanding in order to make high quantity commercial beads together at the same time. As a final point, these are polished through tumbling. Bead mill consists of two laps viz. one grooved while other flat. The spheres turned into beads are rolled between these laps to obtain the perfect pet shape.

Mixing Styles

The universe is crammed in with immense talent. People across the world use their groundbreaking ideas in each and every field like computer, fashion and so on. Similarly, gemstone industry too has billions of artisans who create attention-grabbing art pieces using their pioneer thoughts be it for jewelry items, functional items or decorative pieces. Artists mix different coloured stones in one single art work in a distinctive technique. Few such inimitable examples of mixing styles are inlays, mosaics and intarsia.

Inlays

Inlays are created by mixing gemstones with materials like metal, wood and other stones. The gemstone is cut in the favored shape, glued with the adhesive wax and then fixed into a void nook of other materials as mentioned. This style only uses opaque stones as the beauty of these lies in its façade that is only the outer appearance visible to the viewer. Semi precious stones commonly used as black onyx, turquoise, jade and so on. Transparent stone requires some ray of light that refracts along different facets, sparkles and looks fabulous. Therefore, transparent stones are not suitable as in an inlay once the stone is fixed it has no scope of any light rays.

Intarsia and Mosaics

This is the unique style of mixing that involves innovative and creative designing skills. Both these art pieces are crafted by joining together the coloured stones small in size like pebbles on a flat base material like stone, wood and metal etc. All the stones are top cut and polished in a way that it looks like a picture. It could also be set in some appealing pattern that grabs the attention of the viewer at the first glance.

Then main difference between these two at forms is same as that of cameos and intaglios. Mosaic is produced on the top of plane base of stone whereas intarsia is fashioned into the surface of the foundation material viz. stone, wood or metal. The later is also called as Florentine mosaic or Pietre Dure. The name Pietre Dure suggests, the finest pattern of this skilled artwork is brought into being from the land of artists called as Italy.

Shapes

As cited, in the ingenious world both the artist and the end user are passionate about new and unusual designs. The regular shapes like round and square still exist and shall subsists forever but the demand for something new is increasing at a very rapid pace. Thus, everyday new shapes are created as per the demand of the coloured stones enthusiasts.

Round

This is the standard shape quite common in faceted stones as well as cabochons. It is mostly used as a center stone in necklace or ring fingers. The beauty of this shape increases with the increase in size of the stone.

Oval

Oval is the most universal shape in the jewelry items as it compliments all other shapes very well. It adds an exclusive look to the designs. In cabochons, this shape is idyllic and the exquisiteness of the stone is highlighted very well. All opaque stones get very well cut in this shape. It goes well even for faceted stones.

Square

It is yet another regular shape but less common than the previous two. It is suitable only for those designs that are created with respect to the square cut gems. This shape does not match well with other shapes rather has its own sole significance.

Rectangle

This shape is little unusual for regular jewelry designs, same as square. However, it could be seen in cabochons as well as in faceted stones. Big size single stone cut into rectangle shape hung, as a pendant in a thick black or multi-coloured thread looks quite trendy and is ideal for the casual wear.

Emerald

It is initially cut as rectangle then the four corners are sliced away to give an emerald cut. This is relatively a new shape being like by young generation. Precious stone Emerald in this shape is in style amongst the elite families of the society. The attractiveness of this shape too increases with the increase in the size of the stone.

Marquis

It is a new creative shape, thin at the edges and thick in between of the stone body. The top and bottom of the stone are curved pointed points. Transparent stones are more suitable for this shape than the opaque gems. Female finger rings with gemstones cut in marquis shape are gaining popularity in every corner of the globe. It is also referred as Navettes.

Shield

This shape is proportioned at the sides of the stone but the ends are cut in diverse directions. It is available in different magnitude and varied sides. This is relatively less known and atypical shape.

Cushion

It is shaped similar to the cushions of the sofa or divan in the drawing room. It is more or less like either square or rectangle with its sides smoothly curved. This shape is more used for transparent stones.

Tear Drop

This shape is like a drop of water or tear thus named so. It is pointed at the top and curved as semi circle at the bottom. This is a bizarre shape therefore need to be clubbed along with other shapes to intact the design for any jewelry item. It is also called as pear shape.

Geometrical Shapes

Geometrical design jewelries are new-fangled choice of selection amongst the younger generation who seek fun and frolic in their trendy style. These designs are created using all different shapes of the geometry like triangle, hexagon, octagon, rhomboids, parallelograms and many more. The most remarkable part of these deigns is that it makes fabulous pendants for males. Normally, females dominate jewelries but as for geometrical jewelries it is mostly for males.

Fancy Shapes

image:GemsDB.com

These shapes are fashioned into jewelries that define the sophisticated and elegant aspect of women. The shapes are customized as per the requirement of the user. Few to name are leaf cut shape, princess cut, animals, alphabets, symbols and so on. Leaf cut shape is actually the shape of a new leaf of any tree; gold or silver sleek wires highlight the veins in the leaf. This cut is mostly made in light coloured stone such as peridot, amazonite etc. The absolute gaze of the shape is very charismatic and it represents the skilled craftsmanship of the artist. Similarly, the alphabets are shaped in different varieties of calligraphy. The fancy shapes has indefinite boundaries, it all dependence on ones ideas and thoughts.

This is long journey that the gemstone covers from being found in the lap of Mother Nature to the end possessor. The entire process is intricate and requires attention to the minute details. The hard work and creativity invested gives birth to the beauty.

More Resources
Step by step Gem cutting guide
Gem cutting company
Gemstone cutting terms

admin March 9, 2016 For Gemologists