Seraphinite Properties

The mica inclusions give the stone wonderful chatoyancy. The inclusions grow at different lengths, the longer ones give that feather appearance. Other times you get shorter growth patterns in rows that give the mystic forest appearance. The radial growth patterns in this stone are more highly sought after and make for beautiful designs in cabochons.

Finding Seraphinite

Although seraphinite is getting rather scarce to find, it is still available for sale at shows and online. Most of the time you can easily see what you’re getting, as the patterns will be quite visible on the outside. If you are looking for certain patterns and a higher grade, buying pre-cut slabs is the way to go. If you have never cut seraphinite before, know there are some pitfalls with this material. It’s soft and can easily break in the trimming or cabbing process. It also has varying hardnesses, so it can tend to undercut, as well as easily chip on the edges.

Cutting to Enhance the Patterns

When getting started on cutting slabs, there is a general direction to cut. Most of the time you will see radial or partial radial sprays at the bottom portion of the stone. That will give you a grasp of what is top and bottom, so you can cut north to south for your slabs. This will yield the best chatoyant patterns in the stone. I would also suggest cutting your slabs a slight bit thicker than the average stone because of its softness.

This gives you greater odds against it breaking in the cabbing process. Once your slabs are cut, many times you will get two predominant patterns for design. The top portion usually has smaller feather patterns that are tight together. The bottom portion will give you more radial sprays and longer feathery designs. Both sections are great to design cabs with but remember that the solid green areas are harder than the mica inclusions, and will tend to undercut. The lighter the color, the softer that portion.

Cabbing Seraphinite

Once your preforms are trimmed out and you are ready to cab, I would suggest a different routine than cabbing agates or jaspers. I like to start on a worn 80-grit steel wheel, or a 140-grit soft resin, as this material tends to grind away super easily and quickly. Use a soft touch to shape your outside design, then move to a 140-grit or even the 280-grit soft resin wheel to dome the top and clean up your edges and girdle on the cab.

Remember, the lighter the color, the softer it is, so beware when trying to cab thin cabs or long pointy cabs, it can break easily!

Once you have completed shaping and doming the cab on the 280-grit wheel, stop and dry it off thoroughly and be sure you have removed all the scratches by this point. With the mica inclusions running in a certain direction, you will easily see if there are any scratches, as they will stand out going against the feathery sprays.

From this point, start polishing gently on the 600-grit wheel, trying not to put too much pressure on the surface to alleviate any unwanted undercutting. Continue to the 1200 grit wheel and end on either the 3k grit or 8k grit wheel. At this point, it will give you a nice glossy finish where no added polishing compounds are needed.

This story about seraphinite previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Russ Kaniuth.

The post Seraphinite – What to Cut first appeared on Rock & Gem Magazine.

Although most people know this material for its beautiful blue color, it also can be found in pink and violet. Dumortierite can be found in various places across the globe, and at times, has been mistaken for sodalite, or lapis lazuli. Some variations that have gorgeous fibrous dumortierite sprays inside quartz crystals are rare. These tend to be very small pieces, usually ranging from one to five carats. Dumortierite is a good material for lapidary beginners to get hands-on experience. It’s available almost anywhere rocks are sold in a good variety of colors and patterns. It’s fairly hard, usually about seven to eight on the Mohs scale. It also cuts fairly easily.

Tips for Buying Dumortierite

When buying Dumortierite rough, the colors usually show on the outside, but it can have a thin brown rind that can be chipped away to expose the inner color. Many times the blues can be mottled with a lot of white. If a certain hue of blue or continual color throughout is needed, it’s best to buy slabs to be certain.

Cutting Rough Dumortierite

When starting out cutting rough, there is no certain direction to load the saw. This is helpful so that it can be loaded in a way that best fits the vice and yield the most material by cutting straight across the entire stone in one direction. Once the slabs are cut, there generally aren’t many fractures in this material. However, it’s always best to bench test before marking up the slabs for preform designs. Either flex the slab in hand to see if it’s stable or lightly tap it against the workbench or ground to see if there are any hidden fractures. This helps to avoid breaking while in the middle of trimming out cab shapes.

Cabbing Dumortierite

Once the preforms are cut and ready for cabbing, be sure to have a dry towel or canned air available to check for scratches along the way. Since towels get damp in a hurry and canned air can start getting expensive, one suggestion is to get a five-gallon air tank with a spray nozzle. It can be continually filled up by a personal air compressor or by a nearby gas station and it will last for quite a while.

Dumortierite tends to quickly show heavy white marks if scratches are still present. I suggest starting on an 80-grit steel wheel to shape and dome cabs and moving to either a 60-grit soft resin wheel or 140 soft resin. This material is fairly hard, so it will take a bit of time to smooth it out and remove all the scratches from the 80-grit wheel. Be sure to dry off occasionally and see if any white scratches are showing.

From this point, move on to the 280-grit soft resin wheel. A white or pale blue haze across the cab is to be expected, but not scratches. Make sure no scratches exist before moving forward. From this point, it’s fair routine to continue cabbing to the 600 grit, all the way up to the 14k grit soft resin wheels.

Finishing Gloss

A 50k grit polishing wheel works great to get an added high-luster gloss. Unless going slow in short increments, it’s not suggested to use polishing compounds on this material. Also, be sure not to allow the material to heat up too much. It can tend to fracture with heat.

This story about dumortierite previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Russ Kaniuth.

The post Dumortierite: What to Cut first appeared on Rock & Gem Magazine.

After 30 years of procrastination, I purchased a brand-new rock saw and grinder/polisher. Wow, did I have fun! For that first few months of cutting and grinding, I was in seventh heaven. All those lovely rocks I had lusted after for so long were finally put under my polishing wheel: lapis, agate, jasper, tiger’s eye, malachite, turquoise, chrysocolla and quartz.

But I soon began to experience a nasty and completely unexpected cavalcade of health problems: coughing, hoarseness, difficulty clearing my throat, breathlessness, and a dull ache in the pit of my lungs. Of course, I had always worn safety glasses with side protection, as recommended in every manual, but a mask seemed a cumbersome hindrance. As the situation worsened, I tried several dust masks, but there was little improvement. It was time to do a little research, so I hit the books and started talking to fellow rockhounds. It was a revelation. Rock dust from lapidary work turns out to be more than just a nuisance; it can be deadly.

Dangerous Dust

A single heavy dose can cause crippling lifelong problems. It attacks the lungs in a variety of ways: First, by coating the inner lining and blocking the transmission of oxygen into the bloodstream. Second, tiny sharp fragments slice and cut into the alveoli, which coat the inner lining of the lungs, causing irritation and inflammation. Fresh dust seems to be more harmful because the sharp edges have not had a chance to be softened by moisture. Some forms of rock dust are quite poisonous in and of themselves. Whether it is inhaled, ingested, or contacted by exposed skin, the effect can be injurious to your health.

Copper Oxide Minerals

Among the worst offenders are minerals containing copper (II) oxide (CuO), the higher oxide of copper, which can cause damage to the endocrine and central nervous systems. These minerals include some of our most colorful and treasured semiprecious stones: turquoise (9.8% copper oxide), chrysocolla (45%), and malachite and azurite (70%). These percentages are only close approximations; each rock has its own signature of impurities.

It is worth remembering that other closely related copper compounds are highly bioactive and have been used in pesticides, fungicides, and wood preservatives for decades. This is dangerous material. These high-copper rocks should not be licked to bring out the color, and oil mixed with the dust should be carefully cleaned off exposed skin.

Several lapidaries who smoke have described their own novel test for overexposure: Apparently, copper-impregnated dust combines with nicotine and tobacco tar in saliva to form a sickeningly sweet compound similar to saccharin. When their mouths start to taste like a candy factory, these rockhounds know it’s time to quit. Another sign is influenza-type symptoms. Symptoms of CuO dust poisoning mimic the flu, causing headaches, coughing, sweating, sore throat, nausea and fever. Skin, eye, and respiratory tract irritation are also common, along with a distinct “metallic” taste. A common name for these health effects is “metal fume fever.”

Silicate Minerals

Almost all the rocks most favored by cutters and polishers contain compounds that can be dangerous when inhaled. Silicates are the most common family of minerals on Earth, and silicosis has long been one of the chief hazards facing stonemasons.

The ancient Greeks and Romans were the first to observe its ravages and correctly associated the problem with mining and rockwork. Similar to the “black lung disease” of coal miners, it came to be known in later years as “grinder’s consumption.” The simple steps taken to prevent it were a major achievement in the modern field of occupational health. Ironically, although silicosis is well understood today, thousands still die from its effects every year, mainly from mining and sandblasting in the third world.

The symptoms of inhaling crystalline silica (SiO) dust include shortness of breath, cough, fever, emphysema, pulmonary fibrosis, lung scarring, and increased susceptibility to tuberculosis and cancer. Silicosis often takes many years to develop from repeated exposure to low doses of dust, but once established it is irreversible.

Widespread Silicates

The silicates include a bewildering variety of precious and semiprecious stones. In fact, it’s hard to imagine the world without them, as they can be found in every class of rock and occupy a niche in every conceivable geological environment on the planet.

The family includes quartz, chalcedony, jasper, agate, aventurine, bloodstone, carnelian, chrysoprase, amethyst, opal, onyx, beryl, petrified wood, obsidian, flint, chert, soapstone, sandstone, glass and tiger’s eye. In almost all of these, the content of silicon dioxide approaches or exceeds 50%.

It should be mentioned that African tiger’s eye also exposes the lapidary to another potent danger: asbestos. The vibrant optical effect of its chatoyancy is caused by parallel-oriented, finely fibrous amphibole asbestos. Serpentine has a high chrysotile asbestos content, but this is not considered quite as dangerous as the tiger’s eye. Some soapstone varieties also contain asbestos and should be cut or carved with caution.

Fossil Dangers

Radioactivity from fossils is a hazard that isn’t often top of mind. In a recent study of 300 randomly selected fossils from the Hagerman Fossil Beds of Idaho conducted by C. Neal Farmer, Ronald L. Kathren, and Craig Christensen, a handheld Geiger-Müller survey instrument detected discernible levels of radiation one to two orders of magnitude above the ambient level of background radiation in three-quarters of the specimens (“Radioactivity in Fossils at the Hagerman Fossil Beds National Monument”, Journal of Environmental Radioactivity, Vol. 99, Issue #8, August 2008, pp. 1355-1359). That is a huge difference.

In some areas, like the Hagerman Fossil Beds National Monument (Idaho) and the Morrison Formation at Dinosaur National Park (Colorado/Utah), fossils have even been hunted using Geiger counters.

According to the study, radioactive fossils seem to occur most commonly between 900 and 1,000 meters above sea level in ancient sandy riverbeds, while clay-rich deposits and those at other altitudes do not seem to show these high levels. Apparently, naturally occurring uranium produces radium, which decays into radon, an inert gas. Ancient groundwater transported these radioactive elements into sandy fossil-bearing areas, where they precipitated out of solution during the fossilization process. Even small fossils like shark teeth and trilobites can have significant readings.

The National Park Service is so concerned that it put out a “Conserve O Gram” with detailed instructions for handling and displaying specimens. While it is probably safe to collect most fossils, at the very least, you should wash up and change your clothes after leaving the field. And always wear a respirator when you cut or polish the pieces—radioactive dust is highly carcinogenic!

Tips for Safe Handling

But enough of the doom and gloom. A few simple precautions can almost completely eliminate the threat of injury from most rock dusts. Here is a list of suggestions that will make your workshop a lot safer and allow you to enjoy lapidary work in good health.

1. Wear a Mask

Always wear a National Institute for Occupational Safety and Health (NIOSH) approved respirator with replaceable cartridges and dust filters. Some cartridges today combine a prefilter with the cartridge, which makes things simpler.

Respirators provide a wide variety of protection against dusts, solvents, fumes and mists. They are designated N, R and P, depending on the cartridge’s ability to filter out oil; N stands for “no protection”, R for “resistant to oil”, and P for “oil-proof”. The number that follows the initial tells you what percentage of the particulates is filtered out by the cloth prefilter. For example, an N-95 respirator will not keep out oil spray but will screen out 95% of airborne dust particles.

Avoid cheap dust masks; they don’t fit tightly enough and they filter poorly. If you can, try on several different respirators at the store to get the best fit. Shave your beard, if you have one, to get an airtight seal. Store the mask in a closed container or plastic bag when it’s not in use, and occasionally wash it with warm soap and water, both inside and out.
Try this simple negative pressure test on your respirator: Block up the air inlets, breathe in, and hold your breath for 20 seconds. If the mask is still held airtight against your face, it fits. Cartridges should be changed after about eight hours of use.

2. Work Outside and/or Ventilate

An open window or air conditioner does not provide adequate ventilation for the lapidary workplace. The simplest solution is to work outside. This keeps most contaminants out of your workshop and costs nothing, but it is not always possible.

If inside is your preference, consider setting up a local exhaust ventilation system. This would include a dust hood to collect contaminants, ducts to carry them outside, and a suction fan to power the system. Adjustable blast gates would allow a dust hood to be placed next to each appliance. Ducts should be circular, with as few bends as possible, and should exit the shop. If you have close neighbors or are processing a lot of rock, provide a dust collector to remove contaminants from the vented air.

Setting up such an elaborate system can be expensive and time-consuming for the part-time hobbyist. Some woodworking tool suppliers have come up with an ingenious alternative. They have adapted a wet/dry-type vacuum cleaner with a High-Efficiency Particulate Absorbing or Arresting (HEPA) filter to collect shop dust using a little extra pipe and some suction nozzles. There is no reason this system should not work for rock dust, as well. The vacuum should be placed outside the house because the dust-laden air sucked into the intake will be blown out the vacuum’s exhaust port. Even HEPA filters fail or become clogged, and some dust will always slip through. It’s far better for it to be blasted outside than into the shop or another enclosed area. Kits, diagrams, pipe and suction nozzles are available on the internet. Search for “dust collection” and “dust collection network”.

3. Lubricate

Always use water or oil as a lubricant when cutting, drilling, polishing or faceting, but be aware there are problems with both fluids. When water evaporates, it stops holding the dust down, allowing it to become airborne. A fine oil mist laden with toxic dust can be kept out your lungs with a good respirator, but it will settle on skin surfaces and stick like glue. Also, most lapidary oils are highly irritating or downright poisonous to breathe. Some, like old-fashioned kerosene, are dangerously flammable, as well. Everyone has their favorite method, but I work outside using mineral oil and a P (oil-proof) respirator cartridge with a built-in 100% particulate filter.

4. Cover Up

Always wear a head covering and apron and/or coveralls when grinding, and change clothes after you have finished. Rock dust loves to stick to clothing and hair, and you will carry it around the house and breathe it all day long (as will your family) if you don’t change. Take a shower after your lapidary work, shampoo your hair and use lots of soap. Launder coveralls and work clothes frequently. Disposable clothing, coveralls, and an apron might also be an option.

5. Don’t Sweep

Never dry sweep the workshop. Most of the dust will just become airborne and migrate elsewhere. Use a vacuum cleaner with a HEPA filter instead. If you really want to get down and dirty, use a wet mop on the floor and a wet rag with a water bucket on other surfaces.

Not all of these suggestions need to be slavishly followed. If you grind infrequently, you can probably forget some of them, but if you are an addict like me, you might want to implement most. Individuals vary greatly in their tolerance to rock dust. Some will go through life with nary a problem, but others can be extremely sensitive. Low doses on a daily basis will slowly accumulate, and that dust isn’t going anywhere once you breathe it in. Smoking and living with a woodstove or in an area with poor air quality will make you that much more vulnerable to problems. Listen to your body. If your lungs start to complain, take more precautions; you only have one set to last a lifetime.

FURTHER READING: Health Hazards Manual for Artists, 6th Ed., by Michael McCann Ph.D. and Angela Babin (Lyons & Burford Publishers, 2008)

This story about how to handle lapidary minerals safely previously appeared in Rock & Gem magazine. Click here to subscribe. Story and photos by Douglas Hamilton.

The post 5 Tips to Handle Lapidary Minerals Safely first appeared on Rock & Gem Magazine.

Purchasing Ghost Fire Agate

Since this is a new material, it’s not readily available everywhere just yet, it can be found mostly on Facebook in some of the rock sales forums. When buying ghost fire agate, it’s best to buy from pictures that show at least one side faced, or cut in half, so that you can see what you are getting inside. This material has a great deal of matrix on the outside, and a greater portion inside. It’s best to see how much agate is there before committing to a price that might not yield enough usable agate area to cab since it’s purchased by the pound.

Slabbing Ghost Fire Agate

When starting to slab this material, I cut from two sides, north and west. This way I could see if there were drusy pockets or completely agate-filled nodules. I was able to choose which patterns I liked best. There is no definitive direction to load the stone in the vice, as there are no north-to-south types of patterns in this stone. Start off with the flat sides held tight in the vice. Once you get it cut, if there are large areas of the matrix in the center, I like to cut through them, and downsize the larger stones, so that I can cut smaller ones on a 10-inch trim saw. That way it’s much easier to switch directions with each slab cut, instead of continually loading a vice on the larger saws.

Once your slabs are cut, and it’s time to draw preform designs, you can include some of the matrix that’s still solid enough to cab and not worry about undercutting too much. I have noticed that the plumes grow from areas of the matrix, so I designed them in a way that the matrix is used as a partial framing of the cab. Other times, you can run into patches of beautiful purple and blue agate and isolate that as your cab. The other pitfall to look out for is the calcite that seems to border some of these areas. It’s much softer than the agate and will undercut fairly easily, especially if it’s on the edge of your cab.

Cabbing & Finishing

The cabbing process is fairly routine to most agates, but there are still several ways you can go to obtain the same results. Most lapidaries use a 6-diamond grit wheel setup. For those who still have, or use silicon carbide belts on a poly arbor, they seem to work well in the beginning stages as long as they are on two separate machines, and you rinse the cab off before going back to diamond grit, to keep from contaminating the machine with diamond wheels.

Start shaping and doming on the 80-grit steel diamond wheel. Once you have that portion done, you can continue to a 140 soft resin diamond wheel, or switch to a poly arbor set up, with 100 and 220 silicon carbide belts. The 100 will quickly smooth out the cab and remove all the deep scratches from the 80-grit. The 220 will completely remove any remaining scratches, making it quick and easy to finish the rest of the way on the diamond wheels, starting back on the 600, and all the way up to the 14k.

This story about ghost fire agate previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Russ Kaniuth.

The post Ghost Fire Agate: What to Cut first appeared on Rock & Gem Magazine.

Why Hand Polish?

Hand polishing is something even the most novice and/or youngest rockhound can easily do. It requires only a few materials, doesn’t cost much and results in beautifully polished stones. Some people find the rhythmic motion of hand polishing to be relaxing, offering almost a Zen-like experience. Using the Mohs Scale of Hardness, softer stones like turquoise and amber work best for hand polishing. These stones often don’t fare well in a tumbler anyway, which is one more reason to polish them by hand. 

How to Polish Rocks

Step 1

Start by cleaning the rock(s) by hand. Fill a small bucket with hot, soapy water to clean off dirt. If the stone has a lot of crevices or stubborn residue, an old toothbrush works wonders. Once the rock is thoroughly cleaned, rinse off the soap, then throw out the soapy water and refill the bucket with clean water to use throughout the process.

Step 2

Round the corners and do some rough shaping with 220-grit sandpaper. Begin by moistening the sandpaper and placing it grit-side up on a cutting board or other hard, flat surface. Wet the rock, hold it in your dominant hand and begin rubbing it along the sandpaper to remove the hard edges. Continuously wet the rock to remove fine particles and continue the sanding process until the edges become smooth and rounded or you achieve the desired shape.

To shape and polish harder substances, opt for something coarser. Some people begin with an 80-grit, but sandpaper this coarse shouldn’t be used on softer stones because it could add more scratches than remove. A quick reminder – the lower the number, the coarser the sandpaper.

Step 3

Refine the shape and remove heavy scratches with 500-grit sandpaper. Moving up to finer sandpaper helps remove significant scratches and helps further refine the shape. Keep the rock wet throughout the sanding process for better results.

Step 4

Remove lighter scratches and begin polishing with 1200-grit sandpaper. Using extra-fine sandpaper buffs out tiny scratches on the stone’s surface. The shine will start forming during this step. Make sure to keep the rock wet, rinsing it often to expose anything that’s been missed. 

Step 5

Dampen a square of thick cloth, preferably denim or similar material, and add a good dab of toothpaste. Work the stone through the toothpaste and over the fabric to create a beautiful luster. Depending on the stone, add more toothpaste several times until the desired shine is achieved.

“There are lots of polishing compounds out there,” said Allen McGhee, long-time rockhound and hand polisher. “But I’ve found that toothpaste works just as well, and it’s cheaper. Pretty much any toothpaste works, so don’t buy the high-priced ones.”

Step 6

Rinse off the toothpaste and coat the newly polished stone with mineral oil or a commercial rock polish to bring out the luster. Once the rock dries, it’s ready to show off.

Augmenting with a Dremel

A Dremel is a popular motorized rotary tool that’s handy for grinding and smoothing sharp edges and completing extensive shaping of hard stones, especially those with lots of crevices.

“You can shape and polish rocks and gems faster with a Dremel if you want,” said McGhee. “They make heads for them with all three levels of grit you need.”

When using a Dremel, protective eyewear is a must. Even small chips can damage an eye. Gloves should be used to protect hands. Sharp edges on the rock and the rotating tip of the Dremel can break the skin. Wearing a mask prevents inhaling the tiny particles coming off the rock as it is ground. 

Using a Dremel comes down to personal preference. Some prefer a more natural shape, so they do very little shaping but want to give their rocks a nice bit of shine. Alternately, a Dremel comes in handy for a perfectly smooth and/or rounded stone or for harder rocks that will take a long time to smooth by hand. 

Tumbling Vs. Hand Polishing

Many people inadvertently think rock tumblers offer the fastest way to polish rocks. In reality, rock tumbling is a lengthy process that generally takes anywhere from several days to several weeks. The larger and harder the rocks, the more time tumbling takes. Hand polishing offers a quick turnaround for softer rocks. 

On the other hand, rock tumbling is less labor-intensive since the machine does all the hard work.

Merits of Polishing Rocks by Hand

Although hand polishing can be time-consuming based on the hardness of the rock, it gives more control over the finished product. This control can be especially important if the final result will impact the quality, value and/or overall appearance of a rare or expensive rock or gem. Hand polishing can also give a desirable sense of accomplishment. 

This story about how to polish rocks previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Moira K. McGhee.

The post How to Polish Rocks by Hand first appeared on Rock & Gem Magazine.

For the last two weeks, I have been teaching advanced lapidary bench classes with the California Federation of Mineralogical Societies at their beautiful, forested site called Camp Paradise in the Sierra Nevada mountains. Multiple subjects are taught there including faceting, lapidary, advanced lapidary, soft stone carving, silversmithing, lost wax casting enameling and fused glass.

As a part of my classes, I teach making the tools used in carving the back and fronts of cabs. To my knowledge, these techniques are not commonly taught elsewhere.

Materials Needed

There are four different materials that I use to make my tools: 

• Wood dowels or wood wheels 
• Cratex rubberized wheels (with silicon carbide embedded into the rubber wheels) 
• Silicon carbide Mizzy wheels 
• Silicon carbide sanding blocks 

Wood Dowels

The wood dowels that I use are one-half-inch in diameter. If I have a small hole to work on I use a three-eighth-inch diameter dowel. I cut them into one-half-inch length pieces and drill a small hole into the end to accept the screw end of a half-inch threaded point mandrel. I then shape them by spinning the dowel in a flex shaft unit and applying a coarse wood rasp. I use these rounded shapes to sand and polish the decorative holes that I carve into the back of cabs. To sand the sides of a groove I shape the inside of a wood wheel and use tumbling grit for the sanding media.

Shaped Wheels

The second tool that I use is made from Cratex rubberized wheels. I shape them on a diamond T-bar stone wheel dresser by holding it at an angle to the back side of the spinning Cratex wheel. I use this wheel to sand the sides of a groove.

The third tool that I make is a shaped silicon carbide Heatless Mizzy wheel. It is shaped in the same manner as the Cratex wheel. This wheel is used to carve a groove in a cab.

Silicon Carbide Sanding Blocks

The fourth tools I use in my cab-making process are silicon carbide sanding blocks. They are made from silicon carbide material and are about three-eighth-inches square and four inches long. They come in various grits from about 220-grit through 600-grit. They also come in soft binder and hard binder which is determined by how the grit is bound together. I only use the hard binder. They are used to smooth out the lumps and low places in a carving after the grinding steps. I use them to round out the top shoulder and the V of a V-shaped groove. 

I cut up silicon carbide grinding wheels on my slab saw to make silicon carbide sanding blocks. When I have finished carving the top of rounded grooves on a carving, I shape the end of a silicon carbide carving block with a cylinder diamond bur to sand the top of the rounded grooves. 

I find that by making my own specialized tools I can make the work on my carvings go quicker and with a better overall outcome.

Steps By Photo

This story about making cabochons previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Bob Rush.

The post Making Cabochons with Handmade Tools first appeared on Rock & Gem Magazine.

Many of us have some level of barely started or otherwise unfinished projects stashed away in our studio or shop waiting for the idea or motivation to work on them. Usually, I make my cabs somewhat larger for displaying at shows. I don’t often make my cabs for jewelry use, but this month’s jewelry theme gave me an excuse to resurrect a long-buried, but not forgotten project. 

After struggling to remember what I did with a particular pair of preforms five years ago, I found them together surprisingly quickly. The intended design was to have one piece nested into the larger one. The larger one is a slab of Brazilian agate with contrasting color bands. The smaller piece is a small cab of Laguna agate.

Making the Cabochon

I started with shaping the Brazilian agate slab into a semi-circle with an inverted curve in the bottom to accommodate the smaller cab. I also sketched a design at the top so I could carve a tab that I could drill through for stringing the piece on as a necklace. I shaped the Laguna agate into a pointed teardrop shape sized to fit into the bottom of the larger cab.

I shaped the curve in the larger piece with a silicon carbide Mizzy wheel. The Brazilian agate piece was ready for carving the ridges across the face. I started carving the ridges in the face of the Brazilian agate with a small diamond wheel. I followed this by enlarging and shaping the grooves with a shaped Mizzy wheel. The next step involved sanding the groves with a shaped 220-grit silicon carbide sanding block. The final sanding was done with various shapes of wood bits and a slurry of 220-grit tumbling media. The polishing was done with shaped wood bits and a slurry of cerium oxide.

I drilled the inside curve on the bottom of the Brazilian agate and the top of the Laguna agate cab with a 1mm diamond core drill so I could install a silver wire loop in each of the holes.  I used Epoxy 330 to glue the wire loops into the stones. I assembled the stone pieces by connecting the silver loops. I’m pleased with how the project turned out. 

Steps by Photo

This story about cabochons for jewelry making previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Bob Rush.

The post Cabochons for Jewelry Making first appeared on Rock & Gem Magazine.

Selecting the Right Rock

For hand carving, you want a relatively soft stone, on the order of calcite, or no more than three on the Mohs Scale of Mineral Hardness. Here are examples:

• Soapstone (talc-schist) has Mohs hardness of one. It’s the preferred stone for beginners because it’s soft, inexpensive and common,

• Alabaster (a fibrous form of gypsum) has a Mohs hardness of two. It comes in pastel colors and sometimes exhibits translucency. Alabaster has been a desired carving stone for centuries.

• Marble and travertine can be plain, colorfully mottled, or banded, making them extremely attractive. But at Mohs hardness of three, these take more effort to carve.

• Petoskey stones (the fossil coral Hexagonaria) are carbonate-based and are easily polished by hand. Small cobbles are just the right shape for producing toadstools, which can be found in tourist shops all across Michigan.

Using the Right Stone Carving Tools

Once you have a stone, you’ll need a basic tool kit. Consider including:

• Hacksaws (large ones for slabbing; small ones for trimming)

• Coarse-toothed wood rasps and large steel files (for removing large quantities of stone and basic shaping)

• Small diamond files, straight and curved (for fine work)

• Carving knives, scribes and dental tools (for detailing)

• Sanding boards and wet/dry sandpaper in grits ranging from 180 to 1200 (for smoothing)

• Brushes (for clearing dust off a piece);

• Leather, denim, or cotton flannel infused with aluminum- or tin-oxide (for polishing)

Safety First!

Sawing, filing and sanding raises dust, so work in a well-ventilated area or outdoors and/or have a venting fan and wear a face mask to guard against inhaling dust. The finer you sand, the less dust kicked up, but even if you can’t see it, you’re breathing it. Also, consider wearing fingerless gloves to help guard against nicks when working with knives and scribes.

Getting Started Stone Carving

Most beginning carvers start with a thick, flat rectangular rock slab. They use a marker to draw an outline of what they wish to create. Sketch the proposed object on all sides. Some suggest making a clay model for a 3D guide to follow.

Proceeding Step-by-Step

Step One: Sawing. Use a hacksaw to remove as much excess material as possible from around the sketch on your stone. Proceed carefully so as not to cut off too much or produce deep gouges. This “rough shaping” can be the most time-consuming of all the steps.

Step Two: Filing and Shaping. Turn to rasps and files to round your sculpture into its more-or-less final shape. Start with rasps to take off large edges, then shape with files. Use progressively finer files as you go, starting with steel files and ending with diamond files. It helps to “nest” your rock on a sandbag to keep it firmly in place while working.

Step Three: Sanding and Smoothing. Grits of wet/dry sandpaper go from coarse (40- 60), to medium (80-100), fine (120-180), very fine (220-240), extra fine (320-360) and super-fine/polishing (400-1200+). Hardware stores carry packets with a variety of grits. With softer stones, start with medium-fine grit since coarse grit may leave deep, hard-to-remove scratches. Move to ever finer grits, occasionally brushing or rinsing the rock to remove dust.

Step Four: Detailing. If you want a lot of detail in your work, use steel knives, scribes and/or dental picks. Engraved lines can be smoothed out if desired with very fine curved diamond files.

Step Five: Polishing. Start with extra-fine/ polishing sandpaper. Then thoroughly wash the stone. Mix a paste of water and polishing compound (like tin- or aluminum oxide) and brush it into a bit of leather, denim or flannel to rub a final polish. Sometimes, rather than a polish, colorless beeswax is rubbed in.

Proudly Sharing & Displaying Your Stone Carvings

Carving takes patience. Early efforts might look crude and rudimentary, but don’t give up! With practice, you’ll take pride and satisfaction in transforming dull rocks into dazzling works of art to share at a gem show.

This story about stone carving and polishing by hand previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Jim Brace-Thompson. Carvings by Junior Rockhound Rylee & His Grandpa Dick

The post Stone Carving & Polishing by Hand first appeared on Rock & Gem Magazine.

Faceting Different Versions

The Hoshi’s (Japanese for “star”) size and symmetry of facets on the crown and girdle provide the opportunity to add ornamental facets. I faceted two versions of Marco’s Hoshi for this article. The first one used the design provided and the second was embellished with frosted facets and concave girdle facets.

I jazz this design up a little differently each time I use it. I recommend faceting the design as seen in the faceting diagram first because the girdle is very different and the small crown facets need some time and finer grits to get lined up. Once you facet the diagram, then cut another, adding embellishments to it.

Gem Faceting – Two From One

I used the same piece of Ouro Verde quartz (AKA lemon quartz) rough for both gemstones to show the difference between the two styles in the same color. I did this by using a single longer gemstone that would normally be used for a long rectangle or briolette shape. I preformed the rough and then cut the gemstone in half, giving me two identical preforms. This is a good method for making matching earrings and using longer materials without waste.

I use the Hoshi design in my gemstone faceting lessons. The student facets a round brilliant design for their first gemstone. For the second gemstone, they select either Marco Voltolini’s Hoshi or Maya Drop design. Students get to decide how they want to embellish the gemstone by choosing different facet patterns and the shapes and placement of concave facets on the girdle. This allows the student to try frosting facets, use the ULTRA TEC Fantasy Machine and add their distinct personality.

Ouro Verde Quartz

I like to use Ouro Verde quartz for the majority of my small to medium test cuts. It is a beautiful and affordable gemstone rough that shows off the stone’s best attributes. I recommend my friends at Storied Gemstones when buying gemstone rough. When you call, please tell them I said hello!

If you have any questions about faceting this design or would like to make suggestions for future gemstone designs, please contact me at www.hashnustones.com and use the contact form.

This story about gem faceting the Hoshi gemstone design previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Mark Oros.

The post Gem Faceting: Hoshi Design first appeared on Rock & Gem Magazine.

Andrew’s design is more about the overall appearance, using facets that provide a pleasing and complex composition. The combination of both round and triangular symmetries invites the beholder to reflect on a unique and inviting set of patterns.

Andrew paid special attention to the low refractive index (how much light will bend when entering the gem) for quartz to minimize windowing (losing the reflective nature of the gem’s facets), allowing the gemstone to be seen at greater angles without losing its reflective properties.

For modern jewelry designs, the first place I look is at Andrew Brown’s five gemstone design books. In my opinion, Andrew’s innovative and well-performing designs are on the cutting edge. His designs are either new impressions on classics or a complete break from tradition.

The Super Star design is straightforward and should pose no big challenges to faceters of any level. The design is created for quartz and looks better in a larger gemstone. Larger quartz gemstones can be frustrating to polish so I recommend that you take your time and establish a superior pre-polish before polishing.

Andrew is a prolific gemstone designer and author, having completed five gemstone design books and currently working on his sixth. I had the honor and pleasure of working with Andrew on the faceting book Twelve Easy Gemstone Faceting Designs – A Guide for the Beginner Gemcutter. You can find our book collaboration at https://www. hashnustones.com/twelve-stones1.html. You can find Andrew’s books at https://facetingdesigns.com.

If you have any questions about faceting this design or would like to make suggestions for future gemstone designs, please contact me at https://www.hashnustones.com and use the contact form.

This story about gem faceting the Super Star gemstone design previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Mark Oros.

The post Gem Faceting: Super Star Design first appeared on Rock & Gem Magazine.