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Gem Net is an independent tour operator in Sri Lanka, organize tailor-made Private Gem Mine & Buying Tours to individuals, couples, families, friends and small private groups offering a wide sp…
Gem Net is an independent tour operator in Sri Lanka, organize tailor-made Private Gem Mine & Buying Tours to individuals, couples, families, friends and small private groups offering a wide spectrum of services all meant to make guest feel much cared, home comforted.
Optional extended service has been integrated for additional benefits. Our extended services covers in all sectors of Sri Lanka gem trade- on products and markets, investment opportunities, giving up –to- date and timely information while offering best services for visitors to the country.
Gem Net Personal Advice & Tour Planning Service
Behind Gem Net you’ll find an enthusiastic team of travel professionals who are waiting to help you. Gem Net team, love Sri Lanka, and wish to show the rest of the world this unique and tropical pearl tear drop Island of Gems in the Indian Ocean.
All Gem Net staff members have expert knowledge and their advises will make your tour special. They can co-ordinate all your business arrangements such as your own office professional staff, accommodation, touring options and even family or friends visits, so you can travel in confidence, knowing everything you want to do has been carefully planned for you.
You may be a gem buyer who hunt for your requirement to get the best value for your money, or you may be a gem lover who likes to visit mining sites tour or buying tour, or you just like to discover hidden mysterious places, Gem Net know how to make it happen, and at a price to suit your pocket.
Gemological Tours for Professionals and Geology Enthusiasts
Gem Net organize Sri Lanka gemological tours for visitors, students, professionals and geology enthusiasts willing to learn more and to enhance their resume.
Gem Net arrange for a full trip to like anyone never experienced before. This requires traveling around gem mining areas. The tour will also show where a visitor can buy rough stone at well below the market prices.
See the mines direct and meet the people who find the gem stones. Hear and learn of the knowledge the passed down through the generations from the locals.
For more details Contact:
Info; Gem Net
11/8, 6th Lane, St.Benedict’s Mawatha, Colombo 13
Tel: +94 756407136, +94 723536915, Fax: +94 112336689
Gem mine tour of Sri Lanka, not only allow you to learn about the Gem stones that are taken from the earth and rivers but also allow you to watch how they are polished and cut in to shining pieces. In one way you can say this as an educational tour where you will have the chance to view about the polished and cut gem stones, how the raw stones looks along with the chance to view the mining and the cutting process.
As well Gem mine tours will provide good knowledge about the Sri Lanka gem stones to the participants which will be a valuable one when they happens to deal with valuable gem stones in their countries.
Sri Lanka must be one of the most exiting countries in the world for gemstone enthusiasts, however it is difficult aspect of buying at open gem markets with the excitement heat and pressure.
Don’t let yourself “ lose your cool” street market hawkers hound you to death, about fifty of them pressing in on all sides, and you must remain in calm. Agitation only make things worse, and there is a strong likelihood that poor judgment will result on your part.
Know What You Want:
Decide in advance whether you will purchase cut stones, or rough. It is illegal to export rough stones from Sri Lanka. However , this should not prevent you buying . You can take it to any lapidarist who will be please to cut it for you at a low cost. Cutting time , depending on the stone, would take only one or two hours even hour is possible if you are in rush. The average cost of cutting depends largely on the quality of rough.
Keep your Sense of humor:
This is most important since Sri Lankans enjoy a good laugh , and often local men laugh at you for no apparent reason You should not take offence , and understand that they have a completely different mentality to yours and they do not mean to offend you! Whether laughing with you or at you , try to take it in good natured way. You should join in the fun even if it means laughing at yourself.
The same thing works in reverse , you can laugh at them for whatever the reason and they enjoy the joke !
Sri Lanka has long been renowned for its gems. The history of the gems ofSri Lanka can be traced back some 3,000 years or so. They are part of many legends, folk lore and literary works. In the chronicles, reference is made to gems being brought fromCeylon to the court of Solomon. The “Mahawansa ” the great historical record of the Island refers to the singular reputation of theIsland for its gems. Sri Lanka’s gems are much written about by early travellers from Europe, Arabia and Asia. They have adorned many a Crown, Sceptre and Throne. These gems are the prized possessions of royalty and the rich and famous through the ages right up to this day.
Several Greek writers of the first and second centuries refer to the reputation of Sri Lanka for its precious gems. From about the fourth century to the eleventh century the Arab and the Persians exercised a great influence over the trade of Island. The Venetian traveller Marco Polo in the thirteenth century visited Sri Lanka on his homeward journey from China and his book he mentions the gems of the Island. He also records that he found the Moors, the descendants of the Arabs, in undisputed possession of the gem trade of Sri Lanka. It is also believed that Sinbad’s Valley of gems in the Arabian Nights is probably the Ratnapura gem fields. Sri Lanka has therefore been famous for its gems since early historic times.
The main gem bearing area of Sri Lanka which has been known for centuries comprises a serious of parallel hill ranges separated by longitudinal valleys and situated in the Sabaragamuwa province. To date, the main gemming field in theIslandare confined to this area which covers nearly 1500 sq. km. The neighbourhood Avissawella, Ratnapura, Rakwana and Balangoda has undoubtedly supported the most actively worked gem pits in the Island for a number of decades.
The gem and jewellery industry has been an important part of Sri Lanka’s economy for well over two centuries and remains so even today, and is likely to remain so into the foreseeable future. The majority of economic activity in the industry falls within 3 main sectors, mining, manufacturing and trading. There are four main trading oriented activities which are gem dealing (wholesale), importing, exporting and retailing.
Galle is the ancient port city of Sri Lanka (Ceylon), with a history dating back to probably two millennia. Sir Emerson Tennent thought that the city ofGalleinSri Lankawas the Biblical Tarshish from which King Solomon obtained Ivory, Apes and Peacoks. Arabian Travellers called the city Kalah which was a seaport lying between China and Persia, and was a great emporium of trade in the East. Ships of all nations met there and exchanged commodities. The Arab traders exchanged cotton, silk, gold and silver for ivory, precious and semi-precious stones (Gems) and spices, which were abundantly found in Sri Lanka. Arab traders settled in Sri Lanka in the 8th century-AD.
The port of Galle was much frequented in the middle ages too. It was the chief landmark of eastern navigators. There is an area called China Garden in Galle where Chinese traders once resided, and a Chinese inscription was discovered in Galle which recorded the dealings of the Chinese in Sri Lanka .Ibn Batuta the famous Arab traveller visited Sri Lanka in 1344, and in Galle he found a well established Moor Community engaged in the trading of spices, ivory, gems and jewelry. It is from the port city of Galle that Ibn Batuta embarked on an ancient ship that took him to the Maldives a group of atolls situated about 500km South West from Sri Lanka
Sri Lanka ranks with Myanmar, Brazil, South Africa and Thailand as one of the world’s most important gem bearing nations. The story of Sri Lanka’s gems is as old as civilization itself. Legends, myths and the occult have been associated with the long history of the island’s precious stones.
During the past few decades, many new gemstones and hitherto unknown, yet interesting, gem quality minerals have been discovered. The gem fields ofSri Lankacontain about 75 varieties and sub-varieties of gemstones, some in abundance and some as rarities, which occur both among gem gravels and as components of numerous rock types.
The main varieties of Sri Lankan gems :
Corundum (Ruby, Star Ruby, Star Sapphire, Yellow Sapphire, Golden Sapphire, Padparadscha and White Sapphire), Chrysoberyl (Chrysoberyl Cat’s Eye, Alexandrite, Alexandrite Cat’s Eye and Chrysoberyl), Spinel (Blue Spinel, Red Spinel and Mauve Spinel), Topaz (White Topaz), Beryl (Aquamarine, White Beryl and Pearl Green Beryl), Zircon (Green Zircon, Yellow Zircon, Brown Zircon and the very rare Red and Blue Zircon) Garnet (Rose red colored, Red, Mauve, Hessonite Garnet and Spessartine Garnet), Tourmaline (Green and Brown varieties), Quartz (Yellow, White, Brown, Rose and Purple or Amethyst) and Feldspar (Moonstone)
The Blue Sapphire isSri Lanka’s gem supreme. And her blue sapphires are the finest in the world. The highly priced of all gems, it is second only to the diamond in hardness. The world’s largest known sapphire weighing 42 pounds was found in the gem gravels ofSri Lanka. The Blue Giant of the Orient weighing nearly 500 carats and the 400-carat Blue Belle of Asia, which a British multi-millionaire purchased, were also from this country.
Discovery of a new gem mineral is a very rare event. For it implies that the specimens found are at least large enough to be cut as gemstones suitable for jewellery and usually that they are transparent and pleasingly coloured.
From the trade point of view the recovery of a new gem variety of an already known mineral may be much important.
Ekanite is named after F. L. D. Ekanayake who first found it in a Sri Lanka gravel pit.
Ekanite is green to brown colored rare stone with chemical composition calcium thorium silicate. Thorium is a highly radio active element and due to this element Ekanite is converted to metamict state. In metamict state Ekanite almost acts like amorphous. By applying heat at certain temperature the metamict state of Ekanite can be restored to crystalline state.
Ekanite is an extemely rare gem. It was discovered in 1953 in the gem gravels at Eheliyagoda, near Ratnapura, Sri Lanka. It is also found at Mt. Sainte Hilaire, Quebec, Canada. Ekanite may be strongly radioactive as defined in 49 CFR 173.403 (greater than 70 Bq/gram) due to the presence of Thorium (Th). Ekanite is almost always completely metamict. Metamictization is a natural process due to radiation bombardment that results in the gradual and eventually complete destruction of a mineral’s crystal lattice leaving the mineral amorphous. Ekanite is found in shades of green and brown as are other metamict gems such as low Zircon and Sphene.
Serendibite was discovered at Gangapitiya, near Ambakotte, Sri Lanka, in 1902 by G.T. Prior and A.K. Coomaraswamy. Prior and Coomaraswamy named the mineral ‘serendibite,’ which is derived from ‘serendib,’ an old Arabic term for Sri Lanka.
Serendibite is rarely found as facet-grade material. Before the 2005 discovery of serendibite in Mogok, Myanmar, there were only 3 known faceted serendibites, which were from the original Sri Lankan find. The serendibite from Sri Lanka and Myanmar is believed to be the only sources for facet-grade material. Sri Lankan Serendibite was an attractive greenish or violet-blue, while the stones from Myanmar are dark black.
In the second half of the 1990’s, gem-quality serendibite was discovered from secondary deposits in the Ratnapura area of Sri Lanka.
The Serendibite is very beautiful bluish green gemstone with following physical properties.
(Ca, Na)2 (Al, Mg, Fe2+ , Fe 3+ )6 ( Si, B, Al)6 O20 Pleochroism: strong, L, Yellowish green/ bluish green/ violetish blue , H = 61/2, SG : 3.44 , RI : 1.697- 1.702 B (-), transparent , Glass body , absorption spectrum: one weak line at 470nm.Inclusions: white finger print inclusions, healed fissure, polysynthetic twining, has been founded at Ginigalgoda,Kolonne,Sri Lanka.
This gemstone’s mineral initially discovered and named in 1903 by Mr. Ananda Coomarasamy, for the locality. The Serendib is an old Arabic name forCeylon.
The First SERENDIBITE
Weight: 0.35 ct.
Colour: Very beautiful light medium Emerald green.Shape: Rectangle
Type of Cut: Face: Emerald cut, Bottom: mix protugees cut.
Locality: Gingalgoda,Kolonne,Sri Lanka
An identification report 10035658 has issued by Dr. Mary L. Johnson , Santa Monica, California in Jan .08 1997, Discoverer: Dr. Dunil Palitha Gunasekara, (Dip Gem, SL & GB) Dealer & Gemologist at Crystals Gallery, Gem Lab, 28, Batugedara, Ratnapura Sri Lanka (1996).
Weight: 0.55ct. Colour: Emerald Green ,Shape: Triangular,Type of Cut: Mix cut, Measurements: 4.98×4.95×2.72mm
In year 1996, Dr. Palitha was able to purchase a rough transparent, pebble weighs 1.25 ct from a gem merchant in Kolonne. He has preformed it and has given to his gem cutter with some another gems. after cut and polished it, his gem cutter has asked him if this was an Alexandrite. He has examined it under artificial light and has said it was not, because there was no colour change effect.
What exactly was it, then?,
Possibily a konerupine.
Before exporting any gem, Dr. Palitha customarily check it on his refractometer called “GEM LAB” . When he placed this gemstone on glass prism, he has seen very unusual 3 RI redings, R. I : a = 1.697, ß = 1.700 and ? = 1.702, B (-)
He has jumped with joy. His immediate thought was that this might be a new gem variety, because he has never seen such RI readings before in his refractometer. He has tested it several times on same night , same results has come back.
Other day on date 4th August Aug. 1996 he has written a letter a description paper to Professor as Unknown gem, (with above gem details)
” I think this stone may be a new gem variety, if it correct , please mention the name BONNYNITE, That was my be loving mother’s name, I honored her very much.
Price US $ 55555.00
Dr. Gubelin written him , that reject the price and asked him to get an identification report from GIA Laboratory . Then he has sent it to Dr. Mary L. Johnson , GIA ,Santa Monica,California. They issued a identification report 10035658Jan 08th 1997,
Conclusion : Serendibite , Weight 0.35ct.
One day , Dr. Palitha has examined his old stock of gemstones, He has found a paper packet , wrote as “Doubt stone” ?. By seen the green colour pebble, weight 0.80ct. He has told to his gem cutter, please see another green Serendibite. Then he has tested through his refractometer, has seen the same 3 RI readings.
Both Serendibites has purchased by Prof . Dr. E. J. Gublin. Date :19th June 1999.
Dunilite belongs to the olivine group of minerals, it is a rare mineral and discovered at the Katukubura Hills in the Kolonne area, Ratnapura, Sri Lanka. Dr. Dunil Palitha Gunasekara, Gemologist at the Crystals Gallery, Gem Lab, 28, Batugedara, Ratnapura has discovered this new gem variety in 1996.(Dunilite is a trade name only)
Katukumbura hill .
From Ratnapura on the Embilipitiya road to Colombageare and there turn right towards the Kolonne area and have to walk about 2km on a dusty path to the Katukumbura hill.
The Dunilite crystals has found in Gem pit on top of Katukubura mountain,Kolonne,Sri Lanka, in a deep hole about 5m in length , 3m in width, and about 3m deep . Ferroedenite, Hercynite ( Balck spinel) and some iron oxide were find inside a white calcite rock.
In crystal structure someCrystalare very large, some are aggregate crystals. The Dunilite Occurrence at a contact metamorphic mineral in Calcite, associated with ferro edenite hornblende crystals (MON), Iron oxide and hercynite.
Mr. Palitha Gunasekara has also discovered the Gem variety Metamict Allanite fromSri Lanka. The main varieties of Sri Lankan gems are:
Allanite is very dark in color and seldom cut. The content of the rare earth and radioactive elements causes it to become Metamict with severe damage to the internal crystalline structure.( Dr. Joel E Arem).
Hardness: 6, Specific Gravity: 3.40, Refractive Index: 1.680 Single refraction, Streak Grey. This Gem verity occurrences as rocks inside a gem pit associated with quartz and cassiterite in Goluwahela, Badulla district.
Sizes vary in small rocks to big sizes.( 25.00ct, to 4.0Kg). The Colour is Black and the Outer coat is Brown, The clarity shows Opaque.
This Gemstone has named by Mr. Thomas Allan (1777 _ 1833) Scottish mineralogist, who first observed the mineral Epidote group in 1810.
The discoverer of 02 new Gem varieties and new mineral from Sri Lanka
Mr. Dunil Palitha Gunasekara, (Dip Gem, S.L & G.B) Dealer & Gemologist at Crystals Gallery, Gem Lab, 28, Batugedara, Ratnapura Sri Lanka has found new Gem varieties , (1) Serendibite – Gem Quality( 1996)and (2)Dunilite – Olivine (1996). (3) “Metamict Allanite” (2001).
Mr. Dunil Palitha Gunesekara was born in 27th of October 1947 in Nagoda,Kalutara ,Sri Lanka, has married to Mrs Padma and farther of two daughters Deepali and Dinusha. He has studied at St. Aloysius College, Ratnapura (1957 – 1964) in science in English medium, up to O/L Examination. Subsequently Mr. Gunesekara has done Diploma in Gemology at theUniversity ofCeylon Katubedde Campus Moratuwa in 1971.( Preliminary examination in Gemology in 1971 and diploma in Gemology 2002. Mr. Palitha Gunasekara bears life membership in Gemologists Association of Sri Lanka,he is a member of GAGTL London and also client of GIA ( Client No: 30390802) has served as a Lapidarist, Senior – Valuer, and Gemmology – Lecturer, at the state Gem Corporation of Sri Lanka in 1972 to 1991.
The Bead was probably the first gemstone cut used by man, dating back several thousand years. Limited by the tools available at the time, as well as the hardness of most gemstones, the simple bead or ‘cabochon’ were the logical choice for jewelry making and ornamentation. Stones where shaped by rubbing them with other stones, then polished using ‘sand’ as an abrasive.
Intricately carved cabochon cuts known as ‘Glyptic‘ gem carvings, date back to the 7th millennium BC, and were popularized throughout ancient Egypt (scarabs), Indus Valley, and China (carved jade).
Engraved ‘Glyptic’ gems were used as personal signets or seal-stones which could be impressed into wax or clay to create a signature. The examples above are of early Roman gemstone cuts using the pre-renaissance cabochon cut with several variations of cameo and intaglio styles.
A “lapidary” (edelsteinschneider) is an artisan who works with stone, minerals, or gemstones, forming them into decorative or functional objects. The term “lapidary” is derived from the word lapidaries, which were medieval ‘treatises’ on alchemy, mineralogy, chemistry and other sciences.
Perhaps the best documentarian on the subject of medieval gem-cutting was Theophilus Presbyter (c.1070 – 1125), a Benedictine monk with a fascination for the applied arts. In Theophilus’ ‘On Divers Arts’ De diversibus artibus (c.1125), his treatises on the polishing of gemstones goes into great detail in describing various techniques. For the polishing of “onyx, beryl, smaragdus (emerald), jasper, chalcedony, and the other precious stones” you would make a very fine powder from “fragments of crystal” or “emery” and then work the stone on a “smooth flat limewood board, wet with saliva.”
The ophilus also describes the method for using a ‘dop stick’ by attaching the gemstone to a “long piece of wood of comparable thickness” using “chaser’s pitch,” then rubbing the stone on a wet “piece of hard sandstone,” and decreasing the grit of the abrasive until the stone “becomes brilliant.” Then, using “tile dust moistened with saliva on a goat skin,” you would rub the stone until it is “completely clear.”
To create intricately carved cabochons, cameos, and intaglios out of sapphire, early Roman engravers may have used ‘adamas’ (diamond) fragments as carving tools, given that they are the only material that is harder than corundum.
The simplest form of gem cutting is tumbling. This is where the rough material is put in a revolving barrel with abrasives. Progressively finer abrasives are used, until a polish is obtained. This process closely resembles what happens to rocks in a stream or on the beach, except that the level of polish is much higher.
There are a number of inexpensive settings available so the tumbled stones can be turned into jewelry. These make wonderful, homemade gifts.
Cutting en cabochon, or as it is more commonly known, cutting cabs, is probably the most common form of gem cutting. Cabs are gems that are cut with a flat bottom and a curved or domed top. Cabs have distinct resale value, based on the material they are cut from and their cutting can be profitable.
The first attempts at gem-cutting were to smooth off or round off the stones and polish them by crude methods. Gems were also drilled and used as drops. The old process of cutting is still extant in the various types of cabochon cuts, which include the following: Convex cabochon, lentil cut, high cabochon, hollow or concavo-convex cabochon.
A cabochon (cabouchon) is a gemstone which has been rubbed and polished into a simple rounded shape, as opposed to a faceted cut. Up until the 1400s, gem cutters were constrained to cabochon style cuts and odd asymmetrically faceted cuts due to the limited technology at hand. The resulting shape has a convex top with a flat or concave back. The term cabochon is used to describe any gemstone cut shape that is not facetted.
When a gemstone is cut en cabochon, the miniscule amount of light that is able to enter, and exit through the stone is due primarily to its crystalline structure and optical properties, and has little to do with the gem-cutter’s expertise.
There are several types of carving. One of the best known is cameo. These are usually cut from sea shells or agates, but they can be carved from almost any material. Often cabochons are carved. If the design is cut into the top, it is called an intaglio, or a relief carving. If the design is carved on the back, it is a reverse intaglio. Some carvings are not designed to be used in jewelry; they are cut simply for their beauty. These are classed as stand alone carvings.
Carving is the most challenging of the lapidary arts and there are very few recognized experts in the field. To be successful, one must have a distinctive artistic sense and a thorough understanding of the principles of lapidary. Unlike working in wood or metal, the materials present definite limits as to what can be done.
Faceting is the style of cutting that has the greatest profit potential. If you can envision a diamond, you are looking at a faceted gem. The surface of a diamond is covered with several geometrically arranged, flat surfaces. Each of these flat surfaces is called a facet. The gem is faceted, by a faceter on a faceting machine. This is also where we get the expression, “a multifaceted question.” The purpose of faceting is to bring out the brilliance of a gem. That is where the light entering the stone is reflected off the bottom facets and returned to the viewer. Brilliance should not be confused with dispersion or fire, which is the multicolored flashes you see coming out of diamonds and some other gems.
Naturally occurring facets in crystals were undoubtedly the inspiration for early gem-cutters, motivating them to attempt improvements on nature. It is, and has always been the gem cutter’s task to take maximum advantage of the stone’s potential with a minimum amount of wasted material. Each stone’s optical properties dictate the way in which it should be cut. It is up to the gem cutter to discern the optimal cut for each stone.
faceted Gemstones and diamonds made their appearance in European jewelry during the late 13th and early 14th centuries. With the advent of the horizontally turning cutting-wheel (horizontalen Scheiben) in the late 1400s came the possibility of designing and repeating elaborately conceived geometric faceting schemes, thereby controlling and enhancing the light coming from within the stone.
There is evidence to suggest that some early gems were shaped along natural cleavage lines by knapping, the same technique used to fashion stone spear points. Later, man used grinding and polishing stones mounted in machines that turned them horizontally and were turned by water or human power. This technical advancement led to:
flat(er) facets / more facets / more precise location of facets/ better polished facets through the use of polishing grits/ more beautiful gems available.
Around the year 1400, painters in Italy and other European centers of art were experimenting with the manipulation of light… and the illusion of depth in paintings using light and shadow.
Gem fashioning and the jewelry arts were also located in these art centers. Soon, the manipulation of light in gems became a central theme of cutters. This led directly to new gem shapes and facet arrangements.
This seems to be the time when it was recognized that different facet angles and arrangements needed to be employed for different gems. Refraction and reflection could now be measured, even though they were not completely understood.
From those early days through today, advancements in technology, techniques, equipment, and even new gems have continued unabated. Today’s gem cuts are the finest the world has ever seen.
Faceting methodology consists of mounting a gem crystal on a metal dowel, (dopstick), which fits into a quill, then rigidly addressing the Height-Angle-Index triangle with the faceting machine, and touching the locked-in-place crystal to abrasive laps in two sequential operations, faceting first the top (called the “crown”) and then the bottom (called the “pavilion”).
In faceting, HAI is much more than a casual idiom. It is an absolute ruling principle, expressed as an acronym with it’s
significance focused on “go ahead.” When a faceter can say
HAI to his or her faceting progress, it means “OK to go ahead”
(and facet) because the vital triangle is in place with the gem cutter incontrol of the three principle elements of faceting:
H — height, A–angle, I–index.
Height controls the depth to which a facet is cut and this enables a faceter to establish even, uniform rows of same sized, same depth facets. Angle establishes the plane upon which each facet is cut because optics and performance is so dependant on each facet(s) possessing just the right amount of plane or slant.. Index refers to the placement of the facets around the shape or outline i.e., a round brilliant cut stone, like most diamonds, shows eight main facets when viewed straight down in “plan view.”
The machine to the upper left (Poly-Metric Scintillator 88 Digital) and to the upper right (Facetron) are semi-automated faceting machines. Machines such as these have taken some the guess-work out of stone cutting, but a skilled craftsman must cut a rough stone to its optimal size and and take ito account any inclusions or imperfections that must be eliminated in the cutting process.
By examining the rough stone under a microscope or jeweler’s loupe, the gem-cutter will decide which type of cut will show the stone’s best color attributes, and what (if any) inclusions to avoid.
The Facitron (left) and Scintillator (upper right) are water-cooled faceting machines designed to make cuts at precise angles by mathematically plotting out to depth and degree of a given facet. The rough gemstone is held by a chuck called a “dop” “dop stick” or “dop chuck” and ground against a grinding plate called a “lap”. The rough stone is held to the dop with hot-wax glue.
By adjusting a dial indicator (protractor) the gem-cutter can control the degree of cutting angle to a tolerance measured in hundredths of an inch. The image above (bottom, center) shows a rough gemstone attached to a dop stick. The image to the right (above) is a combination lapidary gemstone saw (slab saw) and grinder.
If the material to be cut and polished is translucent to totally opaque (agate, onyx, malachite, etc.) a cabochon cut will most likely be employed.
Diamond Manufacturing factories use sophisticated electronic equipment for cutting and evaluating cut diamonds. Using the latest hardware and software to create highly accurate 3D models, these scanners measure the angle of inclination of a facet and its azimuth, allowing the operator to pre-visualize a 3D model of the cut stone. Helium Polish Scanners are used for Round Brilliant Cuts as well as Fancy cuts. A device called a Pacor Oxygen Scanner can be used for optimizing rough stones based on purity to evaluate inclusion removal or orientation.
Sri Lankan prefer their traditional equipment when faceting high quality stones in order to control the cutting more precisely and conserve weight. A much higher price is commanded per carat for these stones than for the average commercial grades.
Bow cutting is still in use mainly to cut expensive corundum or to perform other gems. Bow cutting is a hand – driven method especially used to cut star sapphires, chrysoberyl and kornerupine cat’s eyes. This method uses less pressure and so saves weight. Polishing is done using a copper lap with wadi.
This technique conserves weight compared with machine cutting because the pressure can be better controlled and weight loss is reduced. For larger, fine quality specimens a difference of one to two carats may be achieved and native cutting is designed to produce the largest size possible.
Because the machinery is all hand driven, it is safer as working action be better controlled and the lap speed is slower than when electricity is used to drive the wheel.
This technique gives a fine polish, better then that achieved with electrical equipment as because wadi is used as an abrasive , Machine cutting uses diamond powder and coconut oil. Black diamond powder gives a better polish than the white diamond powder. Black diamond powder is more expensive.
Called wadi , the polish paste mixture consists of paddy seed ash , water boiled rice. The paddy seed ash is burnt rice corn shell material. Wadi is used on a copper lap. It is said to be better than diamond dust.
Moonstone is a beautiful and fascinating gem. Its colors are subtle and restrained: taupe, soft brown, green and peach from India, near-transparent from Sri Lanka. The most striking feature of the moonstone is its shimmering iridescent quality. A type of feldspar, moonstone contains thread like crystal structures that reflect the light differently as the stone is viewed from different angles. This is called the Schiller effect, also known as chatoyance.