DOCSLIB.ORG

DIAMOND, PROCESSING, CUTTING and POLISHING Diamond

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
DIAMOND, PROCESSING, CUTTING and POLISHING Diamond DIAMOND, PROCESSING, CUTTING AND POLISHING Websites and Resources on Gems: All About Gemstones allaboutgemstones.com ; Minerals and Gemstone Kingdom minerals.net ; International Gem Society gemsociety.org ; Wikipedia article Wikipedia ; Gemstones Guide gemstones-guide.com ; Gemological Institute of America gia.edu ; Mineralogy Database webmineral.com ; Websites and Resources Diamonds: Info-Diamond info-diamond.com ; Diamond Facts diamondfacts.org/about/index ; Diamond Mining and Geology khulsey.com/jewelry/kh_jewelry_diamond_mining ; Diamond Mine mining- technology.com/projects/de_beers ; Costellos.com costellos.com.au/diamonds ; DeeBeers debeers.com/page/home/ ; Wikipedia article Wikipedia ; American Museum of natural History amnh.org/exhibitions/diamonds ; Book: The Heartless Stone: A Journey Through the World of Diamonds, Deceit and Desire by Tom Zoellner. Diamond Processing and Sorting After diamond ore is mined it is transported to a processing plant where it is first fed into huge crushing machines. In the old days diamonds were recovered on vibrating greased tables. After the diamond ore was crushed it was mixed with water and slid down the table. Because of their surface properties, rough diamonds adhere tenaciously to the grease while other materials vibrate on through. Now the crushed rock is moved on a conveyor belt through a darkened chamber and X-rayed. Photo sensor detect the diamond's fluorescence and air jets remove it. Workers then sort the gem quality stones from the industrial diamonds by hand.<> Gem quality stones are sorted further in the large sorting room at the De Beers headquarters in London. On observing the sorting of five weeks of the world’s production of gem diamonds between two and nine carats in this sorting room, Fred Ward wrote in National Geographic, "I was dazzled with the brilliance of tens of thousands of uncut diamonds. On the counter running the length of the building, keen-eyed workers faced north windows for the indirect, even-color light needed to sort piles of roughs. Eight central tables were laden with sparkling crystals.<> A DeBeers official told Ward, “There are about 180,000 carats on those tables, worth about 70 million dollars. When we have all the stone together for next month's 'sight' or sale, including very small stones and stones over 100 carats, they will bring 250 million.”<> Diamond Cutting Diamond cutters are called lapidarists. Their goal is to get as large and as beautiful a gem as possible from a rough stone without losing too much material. To achieve this goal they essentially use the same techniques they have for the last 600 years. Lapidarist are very careful. They may study a diamond for months before working on it. Student diamond cutter who make two major mistakes fail to get certified. Diamonds can be cut several ways: 1) cleaving, in which the diamond is split with a chisel, is relatively rare these days; 2) sawing with a circular copper blade embedded with diamond dust particles; 3) grinding by pressing the diamond against a covered diamond-dust-covered steel wheel (called a skive) that spins at 3,000 rpms. Even though diamonds are quite hard they are relatively easy to cut along cleavage lines in their crystalline structure. The only thing that will cut a diamond is another diamond. The advantage of sawing over grinding is that sawing leaves behind saleable pieces of diamonds while grinding produces only dust. grounded stones never touch the wheel. They are pressed close but kept away slightly with a layer of oil. Diamond will shatter so great pains are taken to make sure this doesn't happen. They Lapidarists are especially wary of inclusions (black spots) which cause a diamond to crack. Most diamonds give a yield of 40 to 45 percent from rough to polished stone using current methods. Sometimes as much as 70 percent of a diamond is lost during the cutting and polishing process, but the price can jump six fold. The 1977 price for colorless 2½ carat rough was US$750. A flawless one carat stone can fetch as much as US$20,000.<> Types of Diamond Cuts Technology for faceting gems was not invented until the mid-17th century. The round ideal is the standard cut. Developed in 1919 by a mathematician and diamond cutter, Marcel Tokosky, as part of his doctoral dissertation at the University of London, it has 58 facets and was designed to highlight a diamond's light refraction and maximize its brilliance and fire. The Brilliant cut is similar (the same???). It is the most popular shape. Other popular cuts include the Emerald, marquise, and pear. New cuts include the Hearts of Fire, similar to the round ideal except the 58 facets are precisely aligned and polished and reveals a symmetrical heart and arrow when magnified; the Eternal, an 81-facet pedal design introduced in 1999; and the Leo, a 66-facet cut designed to bring out the brilliance. The Gemological Institute of America has devised software to enable retailers and consumers to compare diamonds of different cuts by grading the cut automatically. In most cases, large diamonds are sawed first along lines drawn on it with India ink, grounded and then polished. In 1978, a fist-size 341.9 carat diamond was cut in Belgium using such methods. It took six weeks to cut through the inch and three quarters stone.<> The largest flawless oval-cut diamond in history, a 102.23-carat stone, was cut from a 265.82- carat diamond found in Zaire along with four large diamonds by master cutter Motti Bernstein. When asked about his work, Bernstein said, "When I cut a diamond I don’t think about value; otherwise I get nervous." The value of the 102-carat stone has not been revealed. Another diamond—this one 22-carats—cut from the Congolese stone ended up a with another 22-carat diamond on a necklace for $3.5 million. Diamond Cutting and Grading Technology Some diamond cutters now use computer-driven machines with robot arms that can cut 24 diamonds at the same time. Diamond cutters use computer programs with three-dimensional images to determine the most profitable cuts. In recent years lasers have been introduced that make rough cuts and carry out “bruting” the beveling process used to give diamonds their characteristic sharp-edges shapes. Calibrated Diamonds of Johannesburg is developing an automated laser-cutting system The system can make more precise cuts and even polish diamonds. Researchers at Cambridge University’s Institute of Manufacturing claims they have devised a system that can accurately and consistently grade diamonds and other gems based on clarity. The system, called iGem, works out the value of a rough diamond and suggests ways to cut the stone to maximize value Based on the judgments of four diamond experts who classified 503 “virtual stones, computer models of stones with different kinds of flaws was devised and set of clear rules were established. Gems that are scanned using a desktop X-ray tomography machine and rated according to the system. If a stone falls somewhere in a grey area between ratings , a system kicks that suggest ways to improve the stone’s value tests by iGem show that following its rile sit could increase the value of a stone by as much as 23 percent. Diamond Cutting and Polishing Business Belgium has traditionally been the center of the diamond cutting and polishing trade. The trade for rough and polished stones revived in Belgium after World War II but the crafts of cutting and polishing moved from Belgium to India, Thailand and Israel. There are also large numbers of cutters in Vietnam and Sri Lanka. Most of the stones cut and polished in India are small. The larger stones are cut primarily in Belgium. The world’s largest diamond, the Cullinan, was cleaved by the famous diamond cutter Joseph Asscher, who studied the stone for six month before dividing it into two pieces. After he struck the famous diamond, successfully dividing it the way he wanted, he reportedly fainted and collapsed on the floor of his workshop. Antonio Blanco was one of the most famous diamond cutters in New York City’s Diamond District. His masterpiece was a 100-carat yellow diamond called the Dream that was valued at $20 million. He died in 2009. Diamond Cutting and Polishing Business in Belgium Antwerp is still regarded as world's diamond trading and cutting capital for big stones. One third of De Beers buyers are found here and they reportedly account for 60 percent of all diamond transactions. The diamond trade accounts for $4 billion a year and 6 percent of Belgium's total exports. In the 1990s about 16.8 percent of all polished diamonds imported into the United States came from Belgium by weight of carats and 27.4 percent by value in dollars Antwerp accounts for over 40 percent of the world's diamond cutting and polishing and 60 percent of the trading of large diamonds. Many of the diamonds that originate in southern Africa pass through here on their way from the mines to the jewelry stores; arriving here as raw and uncut stones and leaving as marvelous multi-faceted gems. The first documented diamond deal in Antwerp was recorded in 1447 but the industry didn't take hold into the 19th century when Ashkenazi Jews arrived from Central Europe and built up the city's diamond exchange. The Jewish population of Antwerp dropped from 50,000 to 800 during the Holocaust. The trade for rough and polished stones revived after World War II but the crafts of cutting and polishing moved from Belgium to India, Thailand and Israel. The number of diamond workers declined from 19,000 in 1968 to less than 3,500 today.
Load more

Recommended publications
  • THE CUTTING PROPERTIES of KUNZITE by John L
    THE CUTTING PROPERTIES OF KUNZITE By John L. Ramsey In the process of cutting l~unzite,a lapidary comes THE PROBLEMS OF PERFECT CLEAVAGE face-to-face with problem properties that sometimes AND RESISTANCE' TO ABRASION remain hidden from the jeweler. By way of ex- amining these problems, we present the example of Kunzite is a variety of spodumene, a lithium alu- a one-kilo kunzite crystal being cut. The cutting minum silicate (see box). Those readers who are problems shown give ample warning to the jeweler familiar with either cutting or mounting stones to take care in working with kunzite and dem- in jewelry are aware of the problems that spodu- onstrate the necessity of cautioning customers to mene, in this case kunzite, invariably poses. For avoid shocking the stone when they wear it in those unfamiliar, it is important to note that kun- jewelry. zite has two distinct cleavages. Perfect cleavage in a stone means that splitting, when it occurs, tends to produce plane surfaces. Cleavage in two directions means that the splitting can occur in The difficulties inherent in faceting lzunzite are a plane along either of two directions in the crys- legendary to the lapidary. Yet the special cutting tal. The property of cleavage, while not desirable problems of this stone also provide an important in a gemstone, does not in and of itself mean trou- perspective for the jeweler. The cutting process ble. For instance, diamond tends to cleave but reveals all of the stone's intrinsic mineralogical splits with such difficulty that diamonds are cut, problems to anyone who works with it, whether mounted, and worn with little trepidation.
    [Show full text]
  • Evaluation of Brilliance, Fire, and Scintillation in Round Brilliant
    Optical Engineering 46͑9͒, 093604 ͑September 2007͒ Evaluation of brilliance, fire, and scintillation in round brilliant gemstones Jose Sasian, FELLOW SPIE Abstract. We discuss several illumination effects in gemstones and University of Arizona present maps to evaluate them. The matrices and tilt views of these College of Optical Sciences maps permit one to find the stones that perform best in terms of illumi- 1630 East University Boulevard nation properties. By using the concepts of the main cutter’s line, and the Tucson, Arizona 85721 anti-cutter’s line, the problem of finding the best stones is reduced by E-mail: [email protected] one dimension in the cutter’s space. For the first time it is clearly shown why the Tolkowsky cut, and other cuts adjacent to it along the main cutter’s line, is one of the best round brilliant cuts. The maps we intro- Jason Quick duce are a valuable educational tool, provide a basis for gemstone grad- Jacob Sheffield ing, and are useful in the jewelry industry to assess gemstone American Gem Society Laboratories performance. © 2007 Society of Photo-Optical Instrumentation Engineers. 8917 West Sahara Avenue ͓DOI: 10.1117/1.2769018͔ Las Vegas, Nevada 89117 Subject terms: gemstone evaluation; gemstone grading; gemstone brilliance; gemstone fire; gemstone scintillation; gemstone cuts; round brilliant; gemstones; diamond cuts; diamonds. James Caudill American Gem Society Advanced Instruments Paper 060668R received Aug. 28, 2006; revised manuscript received Feb. 16, 8881 West Sahara Avenue 2007; accepted for publication Apr. 10, 2007; published online Oct. 1, 2007. Las Vegas, Nevada 89117 Peter Yantzer American Gem Society Laboratories 8917 West Sahara Avenue Las Vegas, Nevada 89117 1 Introduction are refracted out of the stone.
    [Show full text]
  • Carat Weight It's the Old Quandary. Is Bigger Better? Size Is Sought After, Naturally; but Overall Quality Counts in the Stretch
    Carat Weight It's the old quandary. Is bigger better? Size is sought after, naturally; but overall quality counts in the stretch. This balance of size and quality makes up much of the art of a professional gem cutter. It is the cutter's job to produce a gorgeous diamond while giving the consumer the highest CARATAGE for his or her money. Caratage means CARAT, the measurement used to weigh a diamond. The word carat is taken from the perfectly matched carob seeds that people once used in ancient times to balance scales. So uniform in shape and weight are these little seeds that even today's sophisticated instruments cannot detect more than three one-thousandths of a difference between them. Don't confuse it with KARAT, the method of determining the purity of gold. What's The Point? One Carat= 200 milligrams, or 0.2 grams. 142 carats adds up to one ounce. Carats are further divided into points. Carat Weight point system What does all this mean, and how does it work? The price of a diamond will always rise proportionately to the size of the stone. Larger diamond crystals are more rare and have a greater value per carat. So, a one carat diamond of a given color and clarity will be much more valuable than 2 one half carat diamonds of equal quality. Cut As the single human contribution to a polished diamond's beauty, cut is perhaps the most important, yet most over-looked, of the Four Cs of diamond quality. How does cut affect a diamond's value and beauty? A good cut gives a diamond its brilliance, its dispersion, its scintillation-in short, its life.
    [Show full text]
  • Cut Shape and Style the Diamond Course
    Cut Shape and Style The Diamond Course Diamond Council of America © 2015 Cut Shape and Style In This Lesson: • The C of Personality • Optical Performance • The Features of Cut • The Round Brilliant • Classic Fancy Shapes • Branded Diamond Cuts • Shape, Style, and Cost • Presenting Cuts and Brands THE C OF PERSONALITY In the diamond industry the term “cut” has two distinct meanings. One is descriptive. It refers to the diamond’s shape and faceting style. The other relates to quality, and includes proportions, symmetry, and polish. Most customers are familiar with only the first meaning – cut shape and style. That’s the aspect of All sorts of cutting shapes are cut you’re going to examine in this lesson. The next possible with diamonds. lesson explores the second part of this C. For many customers, cut shape and style is part of their mental image of a diamond. Shape contrib- utes to the messages that a diamond sends about the personality of the one who gives or wears it. When presenting this aspect of cut, you need to match the images and messages of the diamonds you show with the customers you serve. With branded diamond cuts, you may need to explain other elements that add appeal or value. When you’ve accomplished these objectives you’ve taken an important step toward closing the sale. The Diamond Course 5 Diamond Council of America © 1 Cut Shape and Style Lesson Objectives When you have successfully completed this lesson you will be able to: • Define the optical ingredients of diamond’s beauty. • Describe diamond cuts in understandable terms.
    [Show full text]
  • Making Measurements and Using Testing Tools for Specific Properties of Gem Materials Gemstones Are Very Small and Hold Concentra
    Making Measurements and Using Testing Tools for Specific Properties of Gem Materials Gemstones are very small and hold concentrated wealth. To correctly identify a cut gemstone may in some instances be much harder than trying to identify a piece of rough material. Many gemstone crystals in rough materials have characteristic crystal shape, cleavage, or fracture, but often you can’t see these properties in cut materials — color, density, luster, reflectivity, heat conduction, magnification, and optical properties are ways to look at cut stones non-destructively and identify them. In this lab we will work with some larger stones and make measurements, Such measurements will be applied to specific stones when we learn gems in a systematic way (as we did with minerals) doing individual groups in labs devoted to them. But for now our goal is to learn the instrumentation, including the names and the parts of the instruments. Importantly, we will learn how to handle the testing equipment in a consistent and practical way so as to avoid any damage to either gemstones or to the testing equipment. Measuring gemstones includes their dimensions, weight (or mass), and describing their color, etc. It is sometimes important in their identification as well, a too heavy feeling gem may not be what it appears to be! Weighing Gemstones First 1 gram is 1/1000 (one one thousandth of a kilogram). The kilogram is defined by a piece of metal held in a laboratory in France. However, a gram is also defined as a milliliter of water at 4oC. These measurement units are part of the International System of Units (abbreviated SI from French: Système international d'unités).
    [Show full text]
  • The Ideal Brilliant Cut: Its Beginnings to Today
    MICHAEL D. COWING is the author of Objective Diamond Clarity Grading, an educator, gemologist and appraiser operating an Accredited Gemologist Association Certified Gem Laboratory. His career in diamonds, gems, and gemology spans 35 years. The Ideal Brilliant Cut: Its Beginnings to Today Figure 1. Face-up view of the Ideal Figure 2. 20° Tilt from face-up Figure 3. 20° Tilt forward from the side Cut at its beginning in the 1860’s view of the early Ideal Cut. view of the early Ideal Cut. time frame. Figure 4. Face-up view of today’s Figure 5. 20° tilt from face-up Figure 6. 20° tilt forward from the side view Ideal Cut with fundamentally the view of today’s Ideal Cut. of today’s Ideal Cut. same main angles as the early Ideal. Introduction back angle1.“ It was also known in Europe around the turn of the 19th century as the American Cut. The Ideal Cut’s Since its beginnings in the early 20th century to the present appearance is transformed in Figures 4-6 with today’s day, confusion and misunderstanding has frequently proportions, (larger table size, longer lower girdle facets, surrounded the use (or misuse) of the term “Ideal Round thicker girdle, etc.), while retaining the same fundamental Brilliant Cut,” its defining properties and origin. Some have crown and pavilion main angles which are key to its beauty. advocated eliminating its use altogether. Through the examination of the Ideal Round Brilliant Cut’s (Ideal Cut The Ideal’s beginning with the American Cut hereafter) evolution, this article endeavors to clear up its history, clarify its defining properties and in the process The beginning of today’s Ideal Round Brilliant Cut was the dispel the misunderstanding and mythology surrounding this design attributed to Henry Morse and his diamond cutting most popular of diamond cuts.
    [Show full text]
  • 2019 – 2020 Catalog
    Price MLS $1.00 Minnesota Lapidary Supply “YOUR LAPIDARY SUPPLY GENERAL STORE” America’s Supplier of Quality Lapidary Products FOR OVER 50 YEARS!!!! 2019 – 2020 CATALOG SOME OF THE MANY MANUFACTURES WE STOCK AND REPRESENT: DIAMOND AMERITOOL WHEELS BARRANCA TUMBLERS LAPS DISKS CABKING COMPOUND CALWAY DRILL BITS LOT-O-TUMBLER COVINGTON SAW BLADES DIAMOND PACIFIC DONEGAN OPTICAL The M.L.S. The ROCK STORE WAREHOUSE EASTWIND ESTWING FACETRON FOREDOM GRYPHON HI-TECH DIAMOND ARBORS JOBE KEYSTONE ABRASIVES LAPCRAFT LORTONE MK DIAMOND M. L. S. HOURS Sun. & Mon. ------- Closed MLS Tue. thru Fri. ----- 9:00 am to 5:30 pm (CST) REENTEL Sat. ------------------ 9:00 am to 4:00 pm (CST) ABRASIVES & TRU-SQUARE POLISHES OPEN ALL YEAR LONG!!!! ALL PRICES ARE SUBJECT TO CHANGE WITHOUT NOTICE ANY PRINTING ERRORS ARE SUBJECT TO CORRECTION MLS MLS Trademark Registered - Minnesota Lapidary Supply Minnesota Lapidary Supply 201 N. Rum River Drive Princeton, MN 55371 Ph/Fax: (763) 631-0405 email: [email protected] TOLL FREE ORDER PHONE: (888) 612-3444 WEB SITE: www.lapidarysupplies.com “YOUR LAPIDARY MLS Order Toll Free: (888) 612-3444 GENERAL STORE” Minnesota Lapidary Supply Web Site: www.lapidarysupplies.com To Our Customers: June 08, 2019 As a general overview of the new catalog you will note a much expanded selection of abrasives, carriers and polishes. Also, Lortone has quit making the slab saws they made for many years. [This is truly a great loss – I loved the Panther saw!] This size slabbing saw will be replaced by an equal brand, that being the American made Covington Engineering slab saw.
    [Show full text]
  • Ideal Diamond Depth and Table Percentage
    Ideal Diamond Depth And Table Percentage Christian shapings envyingly while Neozoic Ricardo stake conjunctly or ribbon subtly. Saxon Granville bragged barefacedly while Hanford always mistrust his liveability inhumed totally, he posture so languishingly. Effervescible and sound Kimmo jaunts her Lorenz tinning metonymically or unravelling tactfully, is Zeb fanged? Want both brilliance and counsel so the come for ideal cut flower has influence up. The pavilion angle mark a critical dimension when assessing the quality on a sharp, yet many GIA certificates neglect can include pavilion angle measurements. Marion, the basic Barion cut was an octagonal square or makeup, with a polished and faceted girdle. Diamond cut Grade & Chart Brilliant Earth. Glossary of main Terms with Trade. Table diameter 524 to 575 percent Crown angle 337 to 35 degrees Crown height. Princess Cut Engagement Rings Get The nearly Square. Princess diamonds are a premium cuts, there are guaranteed for someone wants that came in and percentage of love the perfect for? Are all Diamond Shapes More Expensive Than Others. Round cut diamonds will also cost and because some require the post raw material to copper made It takes a larger rough lumber to cut a round diamond the other shapes The total for each carat retained from cutting a round coil is relatively high. Benjamin khordipour is ideal depth percentage can either mask inclusions better user has changed. What type the table percentage on different diamond? 1 Table The aid is the largest facet or a diamond business is located on the burst of great diamond. Our customers demand we offer unique diamond halo engagement rings as well celebrate a handmade rings which come into a greenhouse of stones and materials.
    [Show full text]
  • MODERN DIAMOND CUTTING and POLISHING by Akiva Caspi
    MODERN DIAMOND CUTTING AND POLISHING By Akiva Caspi This article examines the sophisticated o many, a rough diamond looks like any transpar- techniques and equipment currently used ent crystal or even a piece of broken glass. When to fashion a polished gem from a rough cut as a faceted gemstone, however, it becomes a diamond. The basic manufacturing tech- Tsparkling, shimmering object that is unique in appearance. niques—sawing, bruting, blocking, and Yet most of the people who are involved with gem dia- polishing—are described with regard to monds—jewelers, gemologists, and the jewelry-buying pub- the decisions that must be made to obtain lic—are unfamiliar with many of the details involved in that the greatest value from a specific piece of transformation (figure 1). rough. Over the last 25 years, the dia- mond-cutting industry worldwide has The manufacturing of gem-quality diamonds has been revolutionized by sophisticated advanced more since 1980 than in the preceding 100 years. instruments for marking, laser sawing During the past two decades, a quiet revolution has taken machines, laser kerfing machines, auto- place in much of the diamond-manufacturing industry. By matic bruting machines and laser bruting adapting computer-imaging techniques, precision measure- systems, automatic centering systems, ment systems, lasers, and other modern technological and automatic polishing machines. equipment, many manufacturers have improved their abili- ty to cut gem diamonds in ways unimaginable only a few short years before. A significant result of this revolution is a diamond industry that is now better able to operate prof- itably. In addition, modern manufacturers can handle rough diamonds that would have been difficult, if not impossible, to cut by traditional manufacturing techniques.
    [Show full text]
  • MODELING the APPEARANCE of the ROUND BRILLIANT CUT DIAMOND: an ANALYSIS of BRILLIANCE by T
    MODELING THE APPEARANCE OF THE ROUND BRILLIANT CUT DIAMOND: AN ANALYSIS OF BRILLIANCE By T. Scott Hemphill, Ilene M. Reinitz, Mary L. Johnson, and James E. Shigley Of the “four C’s,”cut has historically been the he quality and value of faceted gem diamonds are most complex to understand and assess. This often described in terms of the “four C’s”: carat article presents a three-dimensional mathemat- weight, color, clarity, and cut. Weight is the most ical model to study the interaction of light with Tobjective, because it is measured directly on a balance. a fully faceted, colorless, symmetrical round- Color and clarity are factors for which grading standards brilliant-cut diamond. With this model, one have been established by GIA, among others. Cut, however, can analyze how various appearance factors (brilliance, fire, and scintillation) depend on is much less tractable. Clamor for the standardization of proportions. The model generates images and a cut, and calls for a simple cut grading system, have been numerical measurement of the optical efficien- heard sporadically over the last 25 years, gaining strength cy of the round brilliant—called weighted light recently (Shor, 1993, 1997; Nestlebaum, 1996, 1997). Unlike return (WLR)—which approximates overall color and clarity, for which diamond trading, consistent brilliance. This article examines how WLR val- teaching, and laboratory practice have created a general con- ues change with variations in cut proportions, sensus, there are a number of different systems for grading in particular crown angle, pavilion angle, and cut in round brilliants. As discussed in greater detail later in table size.
    [Show full text]
  • The Art of the Lapidary
    THE AMERICAN MUSEUM OP NATURAL HISTORY THE ART OF THE LAPIDARY By HERBERT P. WHITLOCK OUIDE LEAFLET SERIES No. 65 DECEMBER, 1926 With it 444 perfectly proportion d fa ets t hi blue T opaz a marvelou ex pres ion f the art of the lapidary. ( ase VT) THE ART OF THE LAPIDARY BY H ERB ER1' P. \ i\ HITLOCK Curator of Vlineralogy G IDE LEAFLET No. 65 THE A~IERICAN l\1 E ~1 OF NAT RAL HI TORY ~ EW Y ORK, D ECEMBER, 1926 "And they were stronger hands than mine That digged the Ruby from the earth More cunning brains that made it worth The large desire of a King." -Rudyard Kipling The Art of the Lapidary INTRODUCTION Although a gem mineral in the rough always exhibit certain quali­ tie , which, to a di cernino- eye, give promi e of it po ibilitie a a gem, it i through the shaping and facetting of these bits of mineral that their real charm i developed. Gem tone are, in general, cut 1.-To bring out beauties of color. 2.-To adapt them to jewelry form . 3.-To develop the cintillatino- reflections from the interior of the tone by makino- use of the principle of refraction of light. Th fir t two of the e con ideration are too obviou to require more than a word of explanation. The urface of a tran parent uncut o-em tone may be compared to the urface of a~body of water rendered rouo-h and broken by waves and ripples. It is only when uch a urface ha been rendered mooth that we are enabled to look down into the depth below and ee to be t advantage its color.
    [Show full text]
  • Legend of the Rock: All About Diamonds History
    Legend of the Rock: A Two Thousand Year History of the Diamond ©2010 Whiteflash, Inc. All rights reserved. Introduction When we think “diamond”, we think about wealth, status, glamour and romance. But throughout history, the diamond has been associated with everything from magic, to power, to protection. The history of the diamond is a long and magical one, starting from ancient Greeks and Egyptians and ending on your ring finger. The word “diamond” comes from the Greek “adamao,” or “I subdue,” referring not to a chauvinist attitude towards marriage (we hope), but to the diamond’s hardness and its ability to scratch any surface without being scratched. The word “adamas” was used for diamonds for centuries, although it is not always clear that gem being referred to was actually diamond, or if it was sapphire, the next hardest mineral. ©2010 Whiteflash, Inc. All rights reserved. Diamonds in the Ancient World No one knows exactly who discovered the first diamond. Chances are, that person did not stumble over a chunk of translucent rock sticking out of the ground and exclaim, “Look at the size of that diamond! Someday, it will come to represent the importance of relationships and be worth thousands of dollars a gram!” However it was first discovered, ancient Indian Hindu writings refer to diamonds as the weapons of Indra, the warrior god. Valued at the time both for its exceptional hardness and the flashes of light given off by its natural crystal structure, the ancient Indian word for diamond was similar to the word for thunder and lightning.
    [Show full text]