Faceting My Way by Trevor Hannam

© Copyright 2000 Trevor G. Hannam Page 1 © Copyright 2000 Trevor G. Hannam ACKNOWLEDGEMENTS My deepest gratitude goes to David Tolland, who’s help was invaluable. His assistance in cutting techniques, alignment tools, transfer jigs, and gem holders has made this book a must for all faceters. To Jean Wilkinson and Ray Duncan, for their invaluable help in proof reading and correc- tion of this booklet. To Bearing Service for all the information and their help on Loctite products. Samples of the 2 tonne epoxy adhesives, and UV cement had proved to be very successful, and can be used for transferring dopped gem stones. A special thanks must go to my wife Kay, for her understanding and assistance whilst this book was being written. To present this book in the way it was to be intended, would not have eventuated without their help. Should you wish a copy of this book Contact the Cairns Mineral and Lapidary Club Inc 129 Mulgrave Rd., Parramatta Park (P.O. Box 389W, Westcourt) Cairns Qld 4870 Pages that are damaged through some mishap can be re-supplied @ $3.00 per page Page 2 © Copyright 2000 Trevor G. Hannam INTRODUCTION ave you ever read a book that has so much technical jargon that it leaves you more confused than when you started! I think we all have fallen into this category one time or other. HIt is for this reason that this book has been written. I myself found learning from such a book, if not properly illustrated or explained in everyday terms can be very frustrating and discouraging. Unless you can get an instructor to help you, most beginners will just give it up. The book and associated video (if purchased) contains detailed instructions and illustrations in concise patterns on cutting the Standard Brilliant, and gives the individual a working knowledge on the use of certain gemological instruments. Namely; Specific Gravity (Density), Dichroscope, Polariscope and Refractometer. Books and teachers of faceting often vary in their technique and most still advocate cutting the table first. Times change, and new ways are found to cutting the Standard Brilliant. This book just presents faceting another way, starting with the pavilion and as you read and learn, you will see the wisdom of this technique. There is no hard and fast rule in faceting, just the basics and beginners are encouraged to ex- periment once they have mastered the Standard Brilliant. I feel this book has presented gem faceting in such a way that any average person can learn quickly, and soon develop their own technique in the art of gem cutting. Trevor Hannam 2001 Page 3 © Copyright 2000 Trevor G. Hannam CONTENTS CHAPTER 1 Minerals Page 5 CHAPTER 2 Light and its Properties Page 8 CHAPTER 3 How to Identify Minerals Page 15 CHAPTER 4 What Machine Shall I buy Page 27 CHAPTER 5 Faceting Equipment Page 31 CHAPTER 6 Preparing Copper laps Page 36 CHAPTER 7 Selecting Rough Page 39 CHAPTER 8 The Standard Brilliant Page 41 CHAPTER 9 Dopping Page 42 CHAPTER 10 Rounding Page 44 CHAPTER 11 Cutting the Pavilion Page 47 CHAPTER 12 Polishing Page 50 CHAPTER 13 Transferring Page 55 CHAPTER 14 Cutting the Crown Page 60 CHAPTER 15 Design Your Own Gemstone Page 67 CHAPTER 16 Transposing Angles & Indexes Page 76 CHAPTER 17 Making gem stone display stands Page 77 gemstone papers & Record of Cuts Index Page 80 Bibliography Page 82 About the Author Page 82 Page 4 © Copyright 2000 Trevor G. Hannam CHAPTER 1 - MINERALS inerals are basically formed in primary rocks (igneous) between 600 to 1200 Degrees MCelsius and have a regular atomic structure and chemical composition which is fixed as in Quartz or varied between set limits such as Olivine. 1:1 CRYSTALS Result from any liquid which looses its liquidity, either due to evaporation which causes super saturation of the liquid or from temperature loss from a super saturation solution. Crystals can vary in size from just a few microns to several metres due to the slowness of drying of a supersaturated solution. All Crystals have straight and highly polished surfaces which are called Crystal Faces. Orientation and arrangement of these faces give each of these crystals a distinct form, which is only peculiar to themselves. However! Formation conditions and other chemicals may alter the crystal faces, and is known as Variation. Salt for example, would give a perfect cube, but in reality grows from a cluster due to the growth from a flat or irregular surface. Any solids which are not of a regular atomic structure are called Amorphic - Glass being a prime example of this solid. 1:2 TYPES of ROCKS (a) Igneous or primary - (b) Sedimentary (c) - Metamorphic (a) Igneous rocks are normally classed as either Basaltic or Granitic. Magmas are a molten silicate material plus dissolved gasses produced by partial melting of rocks in the crust and upper mantle of the Earth. This magma is high in peridotite and rises through the mantle through small channels and crevices because of its lower density and viscosity. Vis- cosity is the way that a liquid flows. High viscosity has a low flow, whilst low viscosity has a high flow. This magma eventually penetrates the crust of the earth, and flows out onto the land as Lava. If the lava is cooled fast, fast enough so the lava does not have time to form a regular atomic structure (crystals), it will form into a volcanic glass called Obsidian (amorphic). If this lava has a high gas content (volatiles), it will produce a product we call Pumice, and was originally used as a scrubbing block and sanding material. (b) Sedimentary rocks are derived from minerals that are weathered or from new minerals formed which are layered down to form successive beds. Over time they are compacted or cemented together. 1:3 METAMORHIC MINERALS Changed from heat and pressure to form new minerals or change older minerals. The un- usual thing that occurs here, is that the mineral undergoing the change does not melt, but un- dergoes atomic Structure Realignment. Normally the chemical composition does not change. Page 5 © Copyright 2000 Trevor G. Hannam There are two basic types of metamorphism, (a) Contact and (b) Regional. (a) Contact metamorphism is associated with large granite intrusions where the change occurs nearest the granite. This contact of change is due mainly to heat alone with very little pressure. A good example of this, is when there is a granite intrusion into a sedimentary layer of limestone. The limestone is changed to marble. In this situation there can also be a chemical change due to permeating aqueous solutions from the granite intrusion. The car- bonates from the limestone can be replaced with aluminium and silicates to form the mineral Garnet. (b) Regional metamorphism happens on a much larger scale, and is due to both extreme pressure from deep burial and heat due to geothermal gradient ( 30 degree Celsius temperature increase per kilometre of burial and normal radioactivity in crustal rocks). Bending of mountains that take thousands of years cause metamorphism, and normally causes an alignment of textures which results from the deformation and re-crystallisation of the minerals without changing their chemical composition. Gneiss, being a cabbing stone for the lapidarist, starts its life as a mud shale which in turn changes to slate, to phyllite, to schist, and finally gneiss. 1:4 GEMS & HOW THEY ARE FORMED Gems are mostly formed from hydrothermal solutions and cooling magmas Hydrothermal solutions occur along natural fissures, crevices and veins in rock. As a granite intrusion rises towards the surface it causes the upper mantle of country rock ahead to crack and split causing small to very large fissures. These immediately fill with aqueous solutions (liquid gases) under extreme heat and pressure. As they slowly cool over thousands of years, they form bonded layers of different mineral crystals. Some of these crystals can be enormous in size. Such as quartz. The first minerals that crystallise from the cooling solution are also the first to be weathered or broken down. This order of crystallisation of minerals is known as ‘Bowen's Reaction’. Refer Page 8 for chart Section 1:6. 1:5 ORDER OF CRYSTALLISATION - OLIVINE Gem - Peridot PYROXENE Gem - Augite AMPHIBOLES Gem - Hornblende MICA Gem - Muscovite PLAGIOCLASE Gem - Feldspar ORTHOCLASE Gem - Feldspar QUARTZ Gem - Quartz Page 6 © Copyright 2000 Trevor G. Hannam MINERAL SILICATES 1:6 Bowen’s Reaction Decreasing Temperature Olivine Ca - Plagioclase Pyroxene Amphiboles Ca - Na - Plagioclase Mica Na - Plagioclase Orthoclase Mica Quartz Notes: Page 7 © Copyright 2000 Trevor G. Hannam CHAPTER 2 - LIGHT & ITS PROPERTIES peed of light Travels through air and space at 297,600 kilometres per second, but as it Spasses through a solid object, such as a piece of glass, it does two things. Slows down and changes direction or bends. Why does light slow down? Because it’s passing through a denser material than air. For example, try driving a car through water. The water is more dense than the air, so we are slowed down by it. Why does light bend? As light try’s to pass through the glass it is pulled due to the sudden reduction of speed, because of the higher density. Lets take for example that we are driving on a sealed road, and up ahead there is a small amount of water on the left hand side of the road. As we come to the water and hit it at normal speed, the vehicle is immediately slowed down and pulled to the left. This is exactly what happens when light is passed through the glass.

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