LAPIDARY GUILD

April 2018 Issue Beginner Issue Where did gem cutting Issue No 1 * November 2016 get it’s start?

by Gerald Wykoff, CSM GG

Where did gem cutting get it’s start? 2

em cutting, or lapidary, most The breakage provided random Guide to Gem Cutting Terms 3 Gcertainly got its start as an fragments, but ultimately offshoot of mundane everyday experimentation demonstrat- activities. A stone may have fallen ed that breakage could also be Gemstone Orientation For 9 into a fire where the heat caused it achieved with some semblance to break or flake. Perhaps a sharp of control. Beginners edge resulted. This same knowledge of relative Certainly, flint and other hard hardness led to bruting, the shap- Lapidary Fundamentals: 11 stone possess sharp edges, but a ing of a gem specimen by rubbing blade-like cutting edge on a newly one mineral against another Cabochon Cutting flaked piece of rock suggested harder mineral. The slow and some very interesting possibilities. tedious practice of bruting was used for centuries until more Rock Tumbling: 17 In prehistoric times, man refined techniques were intro- hammered tools from stone, duced. Given the early date, Directions for Turning Rough Rocks into presumably smacking one stone historians are reluctant to Beautiful Tumbled Stones against another. He scratched attribute anything quite so intel- and chiseled out symbols and lectual as an understanding of primitive writings on hard rock cleavages. It was satisfactory and cave walls – and gradually that the breaking, chipping, or Artist Corner: Featuring Keith Cler 21 learned the great secret: some flaking of a stone could be stones are harder than others and disciplined…made to occur in de- therefore they are more capable sired directions and depth. How to Identify Unpolished Agates 23 of inflicting scratches on other less hard stones.From this very basic Later perhaps, someone viewed understanding, drilling and bruting these same stone fragments from became possible. a more abstract perspective. They viewed the unusual configuration, Drilling, one of the first of the texture, or coloring of a piece lapidary arts, traces its roots back of stone or mineral crystal, and almost 1,000,000 years ago. Prim- began to contemplate the possible itive peoples learned that rocks alterations of a stone for artistic or could be broken or fractured. adornment purposes. Tumbling Carving

The simplest form of gem cutting is tumbling. Rough Carving is the most challenging of the lapidary Guide to Gem Cutting Terms gem material is put in a tumbler, a revolving barrel arts. There are very few recognized experts in the field. To succeed at gem carving, you do with abrasives. Progressively finer abrasives are used need a distinctive artistic sense and a thorough by Donald Clark, CSM IMG until the gem obtains a polish. This process closely understanding of the principles of lapidary. resembles what happens to rocks in a stream or on More so than wood or metal, working with gem the beach. However, polish levels are much high- material presents definite limits to what can be apidary is the art of working in stone. However, the word is usually used only in reference er. Tumbling is ideal for children and a great family done and the skill needed to do it. to working with small gem materials, not large objects like Michelangelo’s statues. There pastime. (It’s a great way to work stones collected on L family vacations or rock hunting). It’s easy and There are several types of carving. One of the are four basic styles of gem cutting: tumbling, cabbing, faceting, and carving. (There are also a requires minimal equipment. Plus, the results are best known forms is cameo. These are usually number of ways of assembling gem materials to make jewelry, ornamental objects, and mo- sensational! You can also purchase inexpensive cut from sea shells or agates but can be carved saic-like patterns. You can learn about these techniques from this article on assembled gem- from almost any material. Cabochons are often settings and turn tumbled stones into jewelry pieces. carved. If the design is cut into the top of a cab, stones). This guide will cover gem cutting terms from the four basic fields. ouY can learn more They make wonderful homemade gifts about these techniques in the Fundamentals of Lapidary series. it’s called an intaglio or relief carving. If the design is carved on the back, it’s a reverse inta- glio. Some carvings are not designed to be used in jewelry. They are cut simply for their beauty. These are classed as stand alone carvings.

Cabbing

Cabbing or cabochon cutting is probably the most common form of gem cutting. Cabochons or “cabs” are gems that are cut with a flat bottom and a curved or domed top. If you’ve seen opal or turquoise jewelry, you’ve probably seen cabs. Cutting cabs can be profitable. Depending on the material they’re cut from, cabochons can have sig- nificant resale value. This can make cabbing a very rewarding hobby, especially if you’re cutting materials you’ve found yourself. Cabbing is more complex than tumbling, and a cabbing machine is a bit more expensive, but you can become proficient with a little practice. A word of warning: cabochon cutting can be highly addictive! Faceting Styles Faceting

Faceting is the cutting style with the greatest profit Brilliant Cut Ceylon Cut potential. If you can imagine a diamond in a typical engagement ring, you’re likely visualizing a faceted Examine the round brilliant diagram below left. It has The Ceylon cut has a step cut pavilion and a brilliant gem. The surface of that diamond is covered with triangular and kite shaped facets. This style is called a cut crown. This is an ancient technique still used in Sri several geometrically arranged, flat surfaces. Each of brilliant cut. Lanka today. Modern computer studies have shown these flat surfaces is called a facet. (Some questions, that the reverse, a step cut crown over a brilliant cut like gems, can also be “multifaceted”). Step Cut pavilion, will often produce the greatest brilliance.

The purpose of faceting is to bring out the brilliance Barion Cut of a gem. Light entering the stone is reflected off the A step cut features rectangular shaped facets neatly arranged, one on top of the other. The emerald cut, bottom facets and returned to the viewer. Brilliance The Barion cut was developed by South African dia- shouldn’t be confused with dispersion or fire, which a cut-cornered rectangle shape shown below right, is mond cutter Basil Watermeyer. Essentially, it places is the multicolored flashes you see coming out of the most common example of a step cut. a round brilliant pavilion into a fancy shaped gem. diamonds and some other gems. It usually has a step cut crown as well. This usually results in far greater brilliance than other methods. Gems are faceted by faceters on faceting machines. Interestingly, Mr. Watermeyer invented this cut just There are many kinds of faceting machines. If you before the advent of computer ray tracing programs. want to facet gems for fun or profit, prepare to make a significant investment in equipment. When facet- The round brilliant pavilion, compared to other ing, more so than the other gem cutting styles, your pavilion shapes, offers greater light discipline inside equipment quality will affect both your results and the gem. Barion cuts display a fountain of light effect your enjoyment. that is quite striking!

There are also many kinds of faceters. Faceting is an art, but you don’t need some esoteric Rose Cut “artistic sense” to be good at it. Machinists, engineers, and those with a knack for math often excel at faceting. Many faceters are semi-professionals. They sell enough gems to support their hobby or A gem with a faceted top and a cabbed flat bottom is supplement their income. For those interested in collecting or investing in gems, this is by far the called a rose cut. Occasionally you’ll see a gem with a most practical gem cutting style to learn. The price of rough and labor is almost always less than the faceted pavilion and a domed crown, but this is not a wholesale price of the finished gem. standard method of cutting.

There are two basic styles of faceting: brilliant cuts and step cuts. These styles are often combined. Named Cuts Some cuts combine faceting and cabbing. There are standard, well-recognized cuts like round brilliants and emerald cuts. Most faceted gems are simply called by their shape. However, there are “Although you can become good at many variations within each shape. A triangular gem faceting with a minimum of experience, can have many or few facets, much or little brilliance and scintillation, etc. you’ll never run out of new challenges.” Portuguese Cut Curved Facets

The Portuguese cut has several tiers of facets, which Flat facets are not the only technique available to create a wonderful display of light. It has more today’s gem cutters. scintillation than almost any other cut. As you can see from the picture, it requires many facets and requires Fantasy Cut considerable labor. These factors, in addition to the A fantasy cut is a popular style of faceting. This tech- fact that the rough must have greater than normal nique uses large pavilion facets. Some simple grooves depth, make this cut something that is used only are used, which are mirrored throughout the pavilion. occasionally. This ametrine is an excellent example of a fantasy cut gem.

Some cuts have no name Concave Facets at all. Sometimes, faceters Hand cutting isn’t the only way to make precise, simply use a cut that fits a concave facets. There are now faceting machines that can accomplish this. The gems are first cut tra- piece of rough, something ditionally with flat facets. Then, they’re transferred to another machine for an additional set of concave that just “works.” facets. However, the extra labor required for this is so considerable that this technique is unlikely to see “No Name” And “New Name” Cuts widespread use. Nevertheless, as you can see from the picture below, the results are nothing short of When the GemCad program was released in the spectacular. The brilliance and scintillation exceeds 1980s, people were able to test their gem cutting anything that can be done with flat facets alone. designs on a computer before taking a stone to a lap. This made it easy for people to create new cuts. Today, there are thousands of new designs. Many of these newly named cuts are simply a means to stan- dardize common techniques. For example, someone may “design” the cut used on this red gem and save it with a computer program. They then have an established method for cutting it that can be “There is no end to what referenced and used again. What was once a “no name” cut that just worked for one stone can now a lapidary can do with become a “new name” cut that could work with other stones. gemstones. Keep your

While most newly named cuts are just variations on eyes open and you’re sure standard cuts, some are unique. Indeed, there seems to be no end to the imagination of our to see cuts that are totally lapidaries. There’s no limit to shapes or the number and arrangements of facets. Some new cuts are unique.” merging a variety of techniques. Gemstone Orientation: Gemstone Orientation: Gemstone Orientation: Tourmaline Iolite Topaz

Gemstone Orientation For Beginners I received a batch of orange-pink This material commonly has only I had irradiated material with a tourmaline with well-developed one axis with a strong purple. The patchy brown color that was good Dr. Clive Washington crystals that were virtually emer- others are pale purple or yellow/ down the axis but poor across. ald-cut preforms. The orientation brown. However, the cleavage Since I had to watch out for the was obvious, but I kept in mind the is such that it often comes in cleavage plane, there was only one well-known fact that most tour- thinnish pieces with the dark color choice. I had to tilt the table to the maline has a deeper color looking on edge. Again, I didn’t try to cut cleavage plane by 5º or so. The final Question: down the C axis (the long axis). it for the depth of color. I cut color was much warmer and more I’m a neophyte gem cutter and I have a real fundamental ques- However, cutting with the table across the axis. Again, the internal uniform than the rough suggested. across this axis would have meant reflection picked up the color. The Color, Size, and Shape Factors In tion about gemstone orientation. How do you decide which slicing into a large number of small result was a much larger stone of a Gemstone Orientation triangular stones. That was a silly steely mid-lilac color. In my opinion, way to orient a stone when it is cut? idea. this was far more attractive than For all three stones, cutting at the the dark conventional cut which correct angles allowed light to be In practice, the obvious cut worked attempts to emulate sapphire. reflected within the stone at many well. The internal reflection picked angles, thus mixing up the color. up the C axis color, and the stone This material also had flaws. Many So color problems in the rough are Gemstone Orientation: Basic Factors Visualize Your Options had a good shade when finished. of the stones in my batch had veils often not apparent in the finished (In green tourmaline, it’s almost that would pick up the light only stone. I try to see what sort of shape is suggested by the You sit and stare at the gemstone for a long time. The at certain angles. I ignored all but rough. Try to identify where the table might be and obligatory to cut with the stone more expensive it is, the longer you stare. Seriously, see how much depth is available. Visualize the differ- axis perpendicular to the C axis. the worst of these. As I suspected, Additionally, I had the luxury of gemstone orientation is an area where faceters have ent positions for the table plane and stone axis. Try The color viewed down the crystal they were invisible to the eye in the being able to cut fancy shapes and to build up skill and experience over the years. The to imagine what size and shape could be fitted into can be so intense as to be opaque). final stone. (Although a glass re- non-standard sizes from my rough. decision is usually a tradeoff between many factors, the piece. Narrow the possibilities to a few options. veals them clearly). This made my job easier. If you such as: Making a decision about table placement is critical. A few small flaws appeared near need a particular size and shape, • Do you need a specific shape for the stone? Most things follow from there. one end of the orange-pink stone then you may have to sort through as I started to rough it out. I was several pieces of rough to find one • For dichroic rough, what direction gives the Gemstone Orientation For Maximum Recovery best color? undecided on how much to short- that will work. • What is the shape of the rough? My preference is to go for maximum recovery in en the crystal. Eventually, I decided • Where are its flaws? expensive rough, even if it means the stone has a few to leave them in since they would be below the end facets and not • How many flaws are you prepared to tolerate tiny flaws. Cutting flawless stones can be expensive. You may end up with a lot of small stones. For visible through the table. Of in the finished stone, and where should the general jewelry wear, a few small flaws won’t affect course, if I had decided that they flaws be placed for least visibility? the appearance of the piece. Of course, if the materi- were objectionable in the final • Where are the cleavage planes, and how are al is cheap, you can afford to be more critical. That’s stone, I could Champagne quartz you going to avoid them? one reason why it’s a good idea for beginners to start teardrops, pink tourmalines, and with relatively non-directional things like quartz, • Last, but not least, how expensive or rare is citrines. “Champagne and Berries” the material? synthetic sapphire, and garnet. I’ve recently cut tourmaline, iolite, and topaz. Understanding the by Marianne Madden is licensed reasoning behind my gemstone orientation choices under CC By-SA 2.0 might be helpful to a beginner.have recut it smaller. The Lortone also uses an expanding You can cab on a faceting machine, but Lapidary Fundamentals: drum that’s four inches wide. To use it, you can’t facet on a cabbing machine. If you place a belt around the drum, and, you’re a beginning lapidary student and Cabochon Cutting as the machine comes up to speed, the budgeting your equipment costs, keep drum expands and holds it in place. this in mind. You can shape your cabs Many kinds of belts are available. They with the same coarse laps you use for come in silicon carbide or diamond and faceting. Clean your coarse lap, then put in grits from 100 to 50,000. In the long a piece of firm, 1/4 thick, foam rubber on by Donald Clark, CSM IMG run, these belts cost more than wheels top of it. This will hold pieces of 600 grit with embedded diamond, but the dif- wet/dry sandpaper (that you must cut ference isn’t as significant as with the to shape) for smoothing. To polish, re- abochon cutting is challenging, but with patience and practice, anyone can learn the most popular branch silicon carbide grinding wheels. The place the sandpaper with an Ultra Lap, a Cof the lapidary arts. “Rhodochrosite and gold ring” by Mauro Cateb is licensed under CC By 2.0 primary disadvantage of these belts piece of leather, or other polishing pad Cabochon cutting or cabbing is the most popular form of gem cutting. Although it requires a fair amount of is the time it takes to change them charged with your favorite compound. skill, almost anyone can master this technique. Rough material for cabbing can be found or purchased inex- between grits. You’ll need to com- pensively. Many people never buy their rough and are content to cut the many stones they trade for or find. pletely stop the machine, remove the Slabbing Of course, as you gain experience, you can if you wish move on to more valuable materials like turquoise, old belt, replace it with a new one, and Most cutting begins with a slab. Yes, lapis lazuli, and even phenomenal stones like cat’s eye chrysoberyl and black opal. then bring the machine back to speed. that means you’ll need a saw. Some You’ll need to assess your needs to de- cabs can be cut without slabbing, but cide if this delay is significant enough most will need to be cut into 1/4 to 3/8 to affect your work and/or enjoyment. thick slices. C a b o c h o n Genie, Diamond Pacific The most popular cabochon cutting machine is the Genie by Diamond Pacific. It Rock Rascal Begin by placing a template over the Cutting has six permanently mounted wheels. The first two are 100 and 260 grit dimond One of the least expensive cabochon slab. If your material is a solid color, on solid wheels. The other four range from 280 to 14,000 grit. They have a foam cutting machines is the Rock Rascal. you’re just looking for the largest piece Tools backing, which conforms to the curvature of the stones. There are two mov- It has only one station (so you’ll be you can cut. If the material has a pat- able “geysers” that supply water to the wheels for lubrication. You can’t polish changing accessories constantly) and tern, then you’re looking for the shape everything with one method, so this machine comes with a flat disk that can be Cabbing tools can be holds only one-inch wide wheels. How- and size with the most eye appeal. This mounted on the end. This disk can hold enough varieties of pads and polishing as simple and inex- ever, this tool has been on the market is a bit of a guessing game, since the compounds to polish anything you might encounter. pensive or elaborate for decades, which speaks volumes for pattern will change as you round the and pricey as your The Genie’s advantages are that you never spend time changing accessories and its excellent durability. top. Look at both sides of the slab to tastes run. that the diamond wheels last almost forever. Cost is its primary disadvantage. get an idea of how it will change. This machine is a major investment. It’s also large and heavy, which is fine for a More Options permanent setup. However, if you need portability, this isn’t the unit for you. There are a number of cabochon cut- A template isn’t always necessary. Cabochon ting machines available with a variety Some valuable materials, notably opal, Lortone Cutting of features and prices. Some people are usually cut freeform for maximum Lortone offers a unit lower in price than the Genie with a built-in saw, a silicon have made their own machines. The weight retention. However, you’ll want carbide grinding wheel, an expanding drum, and a flat disk for polishing. The Techniques requirements are: an axle of the prop- to end up with calibrated sizes and quality of the machine and the work you can do with it are both excellent. The er diameter for the wheels you want, shapes with most gem material, since cost reduction comes in the wheels. The oval cabochon a motor, a pulley system to attain the these will fit into pre-made jewelry proper speed, and a method to keep settings. Saving a little weight on most is the most common Silicon carbide wheels round in the center. They soon become difficult to use the wheels wet. This is usually a drip cabs but then having to spend time and shape for cabs. Other and can eventually become unusable. To flatten them, you need a diamond system. Another simple system is a money to make settings isn’t very cost shapes just require tool. These wheels don’t last nearly as long as diamond wheels. A good six-inch sponge arranged to sit in water and effective in the long run. diamond wheel can cost three to seven times as much as an equivalent silicon minor technique constantly wipe the wheel clean. carbide wheel. Although the initial cost of silicon carbide is lower, in the long run adjustments. In this diamond is less expensive. Bear this in mind when replacing a wheel or building section, you’ll learn your own machine. how to cut an oval. When you’ve chosen your area, mark it Start by grinding the excess material “One of the toughest challenges when learning cabochon for cutting. An aluminum pen is ideal for down towards the outline you’ve drawn. cutting is getting the entire gemstone evenly domed.” this. The mark won’t wash away like a Use a pair of calipers to measure your pencil mark. Furthermore, many gem ma- progress. Templates are great for shapes This next step may seem like you’re getting ahead of yourself, but terials will absorb liquid ink, which leaves but aren’t accurate for dimensions. Leave it’s presented just so you know where you’re heading. As you’re an unsightly and costly mess that has to yourself some room for the remaining shaping the gem, leave a small, vertical area on the sides before be cut away. Once your cab is outlined, steps. Depending on the size of your cab, it begins to taper in. Also, sand a very small bevel on the lower take it to the saw and cut away as much you may want to leave a half-millimeter edge of your girdle. This is done in the fine sanding stage. excess material as possible. Until you get or so. This is something you’ll learn from The bevel prevents the edge from chipping and also leaves used to this process, it’s helpful to draw experience. The amount varies with the a small area for solder. guide lines with the aluminum pen and hardness of the material and the size a ruler. of the gem. Sand a very small bevel on the lower edge of your girdle to prevent chipping and allow a little space for solder. If you’re working with a large gem, Once you have the outline shaped, you’ll Cabs are usually placed in a bezel setting. The bezel, you can move on to the grinding stage. start the process called “peeling the a thin strip of metal, is soldered to the main piece. Smaller stones should be dopped to save apple.” Grind a bevel all the way around Hence, you need a little room for the solder. To hold your fingers from unnecessary abuse. the gem at about 45º, bringing it 2/3rd to the gem securely, the bezel needs to be bent inward, 3/4th of the way down to the bottom. over the curvature of the stone. The vertical area on Shaping Then, grind another bevel, all the way the side offers support without having to bend the bezel Now it’s time to start cutting. If you’re around the stone again, at about 60º. too far in. When finished, you want to see mostly the working with something hard, like a Leave some of the previous cut showing. stone. You don’t want the bezel to come so far over the piece of agate, begin with your coarsest Keep “peeling the apple,” cutting bevels edges that it distracts from the gem. wheel. If you’re working with something at increasingly steeper angles, until they soft, like opal or turquoise, or something meet in the center. small, begin with one of the smoother These steps are particularly important with brittle opal stones. If you leave a sharp edge on the girdle, the stone can chip or crack when wheels. If it cuts too slowly, you can “Peeling the apple,” side view of 45° tightening the bezel. The steeper the sides, the more support the gem receives. Of always go to a coarser one, but starting and 60° cuts. This is the area that causes course, this can also be overdone. gently is best. the most trouble for beginners. It may seem that just three cuts will completely Smoothing Bring your machine up to speed and cover the stone, except for maybe a tiny Once you’re satisfied with the shape of your gem, you’ll start sanding out the get your chosen wheel thoroughly wet area right in the center. That’s not good coarse scratches. If you’re using diamond, this will take a series of steps. Typically, before starting to cut. The water serves enough. If you have even a tiny area you’d use a combination like 260, 600, and 1,200 grit. Inspect your gem after each two important purposes. It acts as a that’s flat and not properly domed, the step. Look for proper curvature, as you did before. Also, make sure you’ve removed lubricant, keeping the friction and heat cab won’t take a proper polish. To make all the coarse scratches from the previous step. This is very important. If you don’t down, and carries away the swarf (the matters worse, the flat area will be right get them all out before moving to the next step, you’ll either have to do it again or cutting debris). This keeps the wheel on the very top, where it shows settle for a low-quality finish. from clogging. Most manufacturers the most! recommend you use an additive for ad- The gem needs to be dry for you to see the progress. In a humid environment, this ditional lubrication. Unless your machine You have to be patient and learn to get can be challenging. If possible, warm the room before starting. If you can’t warm is made entirely of stainless steel, you’ll the entire stone evenly domed. Look at the room, at least use warm water. Have plenty of towels available. Dry your hands need an additive with rust preventative the stone from both ends and both sides. before trying to dry the stone.If you are using silicon carbide, all you need is 600 properties as well. The curvature should be even in every grit. It wears fast and becomes the finer grit you need for a pre-polish. direction and all the way to the center. Unfortunately, these have limited uses. You may need to keep two 600 belts. Use Use the lower quarter of the wheel You should make this inspection at every one for shaping and another, well-used one for pre-polishing. when grinding. If you try to work above step, but especially in the first, coarsest the centerline, the gem will probably be stage. Any irregularities are easier to cor- The quality of your pre-polish, the final fine sanding, can’t be overstated. This is the pulled out of your hands. “Pulled” is a rect now than later with the finer grits. tame word for what actually happens. single most important element in getting a high polish. The surface should be ultra The gem will be yanked violently from smooth, with no visible scratches at all. Any time you’re having trouble getting a your hands and flung to the far reaches high polish, go back to the pre-polish step. Soft materials like lapis and opal scratch of your shop. If you can find the stone, readily with diamond. 1,200 diamond is a fine pre-polish for agate, but you might it’ll likely be broken. need something much finer, like 3,000 or 8,000, for softer gems. Polishing can be very confusing for a beginner. There are hundreds of methods. If you buy a new cabochon cutting machine, it’ll probably come with a polishing Polishing system. That’s a good place to start. Cabochons Here are some tricks of the lapidary trade: • Use aluminum oxide on suede, soft side out. This is the most versatile polishing method available. It’ll put a high polish on more materials than any other method. • Quartz responds best to cerium oxide. This does well for opal, too, but be very careful about heat build up with opal. Stones get hot quickly during polishing, and heat can destroy opals. • Jade, on the other hand, needs a lot of heat and friction to polish. Use chromium oxide on leather or felt. • Diamond polish can be used on leather or specially made pads. However, it has never gained the popularity with cab cutters that it has with faceters. It’s more expensive than aluminum oxide and doesn’t offer any significant improvements, except on ruby and sapphire.

These are the most common and most useful polishing methods. With them, you’ll be able to get a mirror polish on any material. That mirror polish is important. It takes a fair amount of work to procure a cabochon cutting machine, learn how to use it, find the rough, orient it, and finally cut a cab. Getting that mirror-high polish on a beautiful stone makes it all worthwhile.

When examining a cabochon, start by judging the polish. Look for any scratches or pitting that will reduce the amount of light reflected from the surface. Judging Next, judge the shape. How even is the contour? A cabochon should have an even Your curvature to its surface. Look at the cab from both ends and both sides. The shape (the curvature) should be a mirror image from side to side. No area should be thick- Cabochon er than its opposite. There should be no bulging. Cutting Examine the shape further by holding the cab so light reflects off its surface. Move the gem so the light travels across the top. If the surface is properly cut, you’ll see the band of reflected light glide evenly over its surface. The band of light will begin to snake if there are any irregularities.

Poor cabochon cutting as well as poor polishing will affect how light moves across the gemstone. You’re most likely to see a problem at the top of the cabochon. Of- ten, a small area will be somewhat flattened. From the side, this is hard to see. How- ever, when light passes over the area, it’s obvious. The fact that light doesn’t flow smoothly over this area is why the cabochon cutting would be considered second rate. (If you look closely, that area probably doesn’t have a good polish, either). Rock Tumbling: “Golden Rules” of Rock Tumbling “Avoid contamination” “Great results take time”

Directions for Turning There are three important rules You will use a different size tum- Don’t be in a hurry. Spend time that we follow in all aspects of bler grit for each step of the doing a great job. If you tumble rock tumbling. These are: Rough Rocks into tumbling process. If coarse grit a batch of rocks through the 1) “Garbage in means garbage Beautiful Tumbled Stones out”; 2) “Avoid contamination”; gets into your medium grit step, it coarse grind and they still have a and, 3) “Great results take time.” will scratch up the rocks and you few rough edges or are not nicely will need to do the medium grit rounded, don’t hesitate to run “Garbage in means garbage out” step over again. So be sure that them through that step again. you thoroughly clean the rocks, Also, spend the time needed to If you start with garbage the tumbler barrel, and your tools thoroughly clean your work area, (low-quality rough), you should when you change from one grit tumbler barrel, rocks, and tools expect low-quality tumbled size to another. between steps to avoid contami- stones. So, don’t hesitate to dis- nation of your rocks. card a rock that is porous, frac- tured, or that will not produce an Another way that contamination attractive tumbled stone. You will occurs is when you use rocks that “Garbage in means garbage spend a lot of time and valuable have a granular texture or are out.” A rock with voids should be supplies tumbling a batch of rocks. brittle. These rocks might break thrown away - the voids will trap Using quality rough saves time, or shed grains or fragments in the grit and contaminate your pre-pol- gives you better value for your tumbler. These grains and broken ish and polishing steps. Protru- Rock Tumbling Is Easy money, and produces tumbled pieces can scratch up every rock sions can be trimmed off with a stones that are of much higher in the barrel. Examine your rocks rock saw - and that might yield quality and durability. sing a rock tumbler to convert rough rock into before tumbling, and don’t tumble two nicely rounded rocks. Usparkling tumbled stones is easy if you follow a suspect rocks in the same barrel simple procedure and observe a few rules. We are with your best rough. Treat new If you don’t have small pieces of writing this to share the procedure and rules that we types of rough or suspicious rock to tumble, you can add small have been using for many years with a number of materials with caution. ceramic media to the tumbler different rotary tumblers. barrel. Ceramic media are used as small-size “filler” in tumbling. This procedure works well with the most commonly These tiny cylinders will also act tumbled materials. These include agate, jasper, pet- like roller bearings in the barrel rified wood, quartz, and other materials with a Mohs and make your load tumble with hardness between 6 and 8. a smooth action - that smooth action will improve the grinding in It also works well with materials such as natural and the barrel and keep your stones man-made glasses that have a hardness of 5 to 6. from being bruised. View our video Examples are obsidian, Apache tears, and landscape at rocktumbler.com to see about glass. With these materials, the coarse, medium, and selecting the right tumbling media. fine grit steps can usually be shortened to five days, but the polishing step should remain at seven days. The results are amazing! Inspecting Your Rough Loading the Tumbler Barrel

Remember the rule “garbage in means garbage Before you load the tumbler barrel, be sure that it is out.” Practice that by starting with quality rough, perfectly clean. There should be no grit or rock and you will have a chance to produce high-quality fragments left in the barrel from a previous tumble. tumbled stones. We prepare to tumble by examining To prevent leaks, the rim of the barrel and the lid our rough rock. If we find porous pieces that will not make nice tumbled stones and will carry grit from should be totally free from grit or rock particles. one step to the next, we discard them. Once you have a clean barrel, add enough rock to fill Rocks that are fractured will break while tumbling the barrel about 2/3 full. If you don’t have enough and scratch other rocks in the batch. When we see a rough to fill the barrel about 2/3 full, the rocks can be fractured rock in our rough we discard it or break it tossed around in the tumbler and bruised. (Obsidian along that fracture before it is placed in the barrel. and crystalline varieties of quartz bruise very easily). If you don’t have enough rocks, you can For best results, your tumbler barrel should add ceramic media to bring the barrel be loaded with rocks of mixed particle size (from about 1/4 inch up to about 1 up to a proper operating level. 1/2 inches in diameter for a 2-pound or 3-pound capacity barrel). If you have Now you are ready to begin what only small material that’s OK... just most people call the “Four-Step follow the instructions below. Tumbling Process.” This is described below for a rotary However, if you only have large tumbler with a three-pound ca- rocks, then you should add some pacity barrel such as the Thum- smaller material (small rocks are ler’s Model A-R1, Thumler’s needed to carry grit to all of the surfaces of the larger rocks). You Model A-R2, Lortone Model 3A, can also add some small ceramic or the Lortone Model 33B. tumbling media to get smaller par- ticles into theload. For best results, If you are tumbling with the any load that you tumble should have Thumler’s Model MP-1 tumbler at least 25% small particles. (which has a two-pound capacity bar- rel), you can follow the instructions given, Finally, tumbling works best when all of the but use about two level tablespoons of grit or rocks in the barrel are about the same hardness. If polish in each of the tumbling steps (Step 1 through soft rocks are tumbled with harder rocks, the softer rocks will wear away quickly. When loading the tum- Step 4). bler barrel, you should have pieces of rough with a range of particle sizes. We would mix the above sizes When tumbling you will place enough rocks in the together in the barrel. barrel to make it about 2/3 full. Then, add about two level tablespoons of grit for each pound of rock. If you load the barrel with just a few large pieces, Finally, add enough water to almost cover the rock. there will be very few points of contact between the Now seal the barrel and place it on the tumbler. rocks in the load. Those points of contact are where grit is trapped between the rocks and where grind- ing occurs. If you have lots of small pieces of rough between the big pieces, there will be many points of contact between the rocks of the load, and the tum- bling process will be faster and more effective. Artist Corner: “Some of Keith Cler on how my favorite he got started in materials Lapidary work are Koroit opals (and

apidary work started at an early age for me. I was learning to cut gemstones when I was ten years old. As a other Austra- Lkid, I cobbled together anything that would grind and polish a rock. Several men cared enough to mentor and share with me the skills that took them years to learn. I traveled to rock and gem shows with a neighbor who was also our family doctor and responsible for delivering me and most of my five brothers and three sisters. I attended rock club meetings, participated in gem shows and sold cabochons in my teen years. I began faceting lian opals), when I was in high school which added another huge lapidary challenge. In my mid-twenties I set my rocks and equipment aside to raise my family and work in the family business. I agates, worked as a machinist for many years then moved into design and engineering, eventually sales and then landed in a production management roll…all in the same family business. When our three sons left home, once again I had more time and for my interest in gem cutting. Since then I have focused on cutting and selling Koroit opals. jasper, Included in my quest to cut beautiful gems I have a strong interest and enjoy building my personal lapidary equip- ment. Some of my favorite materials are Koroit opals (and other Australian opals), agates, jasper, turquoise and jades. turquoise Outside of my interest in lapidary, I enjoy hanging out with my wife, love traveling, hiking in the mountains, riding my motorcycle, parks, camping, fishing, photography, building machines, video editing, wildlife, and playing the banjo. and jades.”

I have a passion for lapidary and the challenges that go along with cutting different types of gems. I hope you, your friends and your customers to enjoy the stones as much as I did cutting them!

I’m a guy that’s crazy about rocks...I am young at heart.

Connect with me: http://www.etsy.keithcler.com How to Identify Unpolished Agates Subscribe By Lanh Ma Lapidary Guilld is a quarterly magazine. Visit www.lapidaryguild.com/subscribe

gates are semiprecious gems Measure the stone. In most Feel for any waxiness in the Athat can be found all over cases, the average agate is less revealed stone. When you see a the world. Throughout history, than 3 inches in diameter. crack in the stone or a place where they have been valued as stones the rocky exterior has worn away, of impressive beauty and charm. Heft the stone. Most agate slide your fingers across it. Waxi- Most people recognize agate as a pebbles feel heavier than they ness is a sign that you might have highly polished, banded stone, but look due to their dense compo- an agate. recognizing unpolished agate on a sition. You may wish to compare lake or in a freshly plowed field is them with other stones that are Look for conchoidal fractures, a little tougher. Identifying unpol- lying close by. which are irregular fractures that ished agate is something that any occur in fine-grained materials amateur geologist can learn to do. Look for a pit-marked surface such as glass and obsidian. These on the rough stone. Agates can be fractures are often curved, with a Look for translucence in the formed in igneous rock, and they wavelike pattern, and they result stone. If the stone has been bro- can also be surrounded by softer in a very irregular profile to the ken and you can see telltale traces rock that has since eroded away. rock itself. Agates are prone to of a quartzlike mineral along with Both of these features can leave conchoidal fractures, and seeing a the red, brown and orange color the agate with some pitting. rock with a distinct profile can alert that comes with many types of you to an agate’s presence. agate, there is a good chance that you have an unpolished agate. www.lapidaryguild.com USD $14 CDN $17