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.

“Under the rocks and stones, there is water underground.” ~ Talking Heads

The answer lies in (among other places) the lyrics of the 1970’s art rock band, Talking Heads: Water.

Rock Tumbling Blow Up

Rock tumbling began millions of years ago, as waves and streams tumbled Earth’s first sediments. Over time, the more ingenious of our ancestors discerned how such natural processes shaped and smoothed some rocks more than others. Moving water became the first “rock tumbler.”  

For thousands of years we have respected the power of water but only recently has science explained how something so benign and malleable can wear away stone.

In April 2022, a first-of-its-kind study, led by University of Minnesota-Twin Cities researchers, announced it had taken a closer look at how water erodes hard surfaces and concluded that tiny droplets behave like miniature bombs. 

“There are similar sayings in Eastern and Western cultures that ‘dripping water hollows out stone,’” said Xiang Cheng, senior author of the research paper and associate professor at the University of Minnesota Department of Chemical Engineering and Materials Science. 

“Such sayings intend to teach a moral lesson: ‘Even if you are weak if you do something continuously, you will make an impact.’ But when you have something so soft as droplets hitting something so hard as rocks, you cannot help wondering, ‘Why does the drop impact cause damage?’ That question motivated our research.”

Their discovery, published in Nature Communications, outlined how a new technique called high-speed stress microscopy measured the force, stress, and pressure underneath liquid drops as they hit a surface. They found that the force exerted by a droplet spreads out with the impacting drop instead of concentrating in the center of the droplet, briefly exceeding the speed of sound as it spreads and creating a miniature “shock wave” across an impacted surface.

“Each droplet,” the team noted, “behaves like a small bomb, releasing its impact energy explosively and giving it the force necessary to erode surfaces over time.” 

And to think, all those micro-bombs were organically exploding as Egyptian slaves slushed rough-hewn rocks, for months at a time, in troughs filled with sand and water. Or, as Indian lapidaries rolled goat skin polishing bags filled with water and grit along the ground, or shook jars of water, abrasives, and pre-cut beads up and down on pre-tumbler “teeter-totter” boards. 

Rock Tumbling Glow Up

That said, not every type of stone is up to the task of enduring microscopic bombings in pursuit of that perfect shine.

“We were the first in the area to carry raw stones because it was growing more popular. People want to tumble their stones,” says Christine Seebold, evidential medium and owner of the Mind Body Spirit Center, with locations in Albany, Clifton Park, and Saratoga Springs, New York. 

“We try to give everyone a variety of stones to try, plus we do a rock tumbling kit for kids, which includes two dozen of the best basic choices.”

What makes the best basic choice? A great place to start is at that tried and true standard established in 1812 by German mineralogist, Friedrich Mohs. He chose 10 different minerals of varying degrees of hardness and assigned them a score of one (softest) to 10 (hardest). 

The ideal Mohs scale of hardness for rock tumbling success is between five to seven. One of the tumbling’s easiest tips to remember is ‘seven days for a hardness of seven,’ and standard rock tumbling instructions are generally based on material with a Mohs hardness of about seven (including agate, chalcedony, jasper, quartz, and petrified wood).

In Why Mohs Hardness Is Important, Hobart M. King of Rocktumbler.com wrote, that if you are tumbling a rough with a hardness of six, it will not take as long to shape and smooth as a rough with a hardness of seven. “Our opinion is that you can reduce the number of tumbling days by about one-and-a-half days for every degree of hardness under seven.”

Agate, Chalcedony, and Jasper, Oh Mohs!

Quartz is the benchmark mineral for a seven on the Mohs Hardness Scale and standing toe to toe with it is another top choice for tumbling, chalcedony. 

Don’t let its occasional delicate transparency and a wide variety of hues (thanks to impurities in an otherwise colorless state) fool you. Chalcedony can roll with the best of them and is the generic name for any kind of microcrystalline quartz, although its white and blue forms are most often referred to as chalcedony. (Fun fact: it’s also the “flint” used in ancient tools and weaponry.) 

Agate and jasper are varieties of chalcedony. All are colorful, durable, inexpensive, and deliver a satisfying luster after tumbling. An easy way to remember one from the other is that agate is any type of chalcedony that is translucent; jasper is chalcedony that is opaque, thanks to a greater degree of impurities mixed with its silica/quartz. Agate and jasper can form in the same volcanic environment so it’s not uncommon for a single rock to contain both translucent (agate) and opaque (jasper) portions.

Polished agate as ornamentation dates back to the Bronze Age (3300 BCE – 1300 B.C.) in Asia, and third-century B.C. Greece, it derived its name from naturalist Theophrastus, who named agate after the Sicilian shoreline of the Achates River where he found the stones. Popular agates include descriptive lace and moss agates, turritella (including petrified wood), and iridescent fire agate.

Varieties of jasper include imperial (green), the rarest — according to writer and rock seeker Jeremy Hall — so be sure of what you’re buying; brecciated (colorful red and yellow nodules); the dreamlike landscape; poppy, named for its distinctive tiny “blooms,” and ocean, found only at low tide in Madagascar.

Other types of chalcedony to consider for tumbling are aventurine, whose tiny inclusions look like shimmering flakes; carnelian and heliotrope (aka “bloodstone”); blue (Mt. Airy Blues or Mohave) or slightly lavender chalcedony, known as holly blue and found only in Oregon; and since the organic matter in petrified wood is often replaced by (opaque) chalcedony, it can technically be classified as jasper (and tumbles at roughly the same rate, four to five weeks, as agate or jasper).

Christine says other rocks her collectors love to tumble are quartz and tiger’s eye. Tiger’s eye, a crystalline type of quartz, can be polished to a high luster but experienced tumblers warn that tumbling pieces larger than an inch in size can result in “bruising” along the edges of the rocks, caused by quartz-on-quartz impacts inside a tumbling barrel.

Your best prospects are hard, dense, and smooth rocks like those mentioned above; avoid tumbling rocks with a gritty texture or that prove too soft after a “scratch test” (where a mineral, after being scratched by another mineral, will fall on the Mohs Hardness Scale).

Rockin’ Tik Tok

What’s hot in rocks is also being determined by younger, more social voices.

“We have kids come in the store educating their parents,” says Christine. “TikTok videos are teaching a lot of kids about stones and crystals. By the time they come in the store, they already know what they’re looking at and what they want. They say, ‘This way, Mom.’ They already know the stones they want.”

Driving popularity can also drive demand for certain rocks.

“Muldovite,” sighs Christine, citing a recent example of a rock so popular (thanks to TikTok) that it was hard to keep in stock or, from a metaphysical standpoint, align with the right energies.

“This is a really intense stone of transformation and spiritual awakening,” she says of the rare green tektite from the Czech Republic. “I had three people in one week come into my shop asking for it, and when I asked, ‘Are you sure? That’s a strong stone,’ they said, ‘Yes. We saw it on TikTok.’”

She’s not exaggerating. An April 30, 2021 article in Cosmopolitan by Rebekah Harding cited how muldovite, during the pandemic, racked up more than 280 million views on TikTok and its digital spiritual cousin, WitchTok. 

“There’s a neat reason this tektite became one of WitchTok’s biggest and most long-lived trends,” Harding wrote. “Moldavite removes blockages and obstacles on your path toward becoming your highest self. Often in the most chaotic way possible.”

So, muses Christine,  “If you can’t find a certain stone, it might be because it is selling out on TikTok as ‘Stone of the Week!’” 

TikTok trends are a long way from the days of goatskin bags and sand-filled troughs, and yet the attraction we feel for a pretty, shiny stone endures.   

This story about rock tumbling previously appeared in Rock & Gem magazine. Click here to subscribe. Story by L. A. Sokolowski.

The post Best Rock Tumbling Rocks first appeared on Rock & Gem Magazine.

Moving Headquarters

In January 2020, the company moved from Redlands, California, to Meridian, Idaho.

“We believe the timing of the moving was nothing short of miraculous. Because we moved when we did, we were able to continue the production of equipment through the pandemic. Our new factory allowed our employees to be socially distanced from each other, maintaining safety throughout the shutdowns,” said Ashlee Emoto, general manager of Covington Engineering. “Being essential to aerospace, oil field industries, and other scientific fields meant we had to maintain production, which was vital to many customers and to our employees.”

In 2021, Covington Engineering purchased the Ameritool line of products and supplies. According to Emoto, this  is considered a “match made in heaven.” In fact, in the spring of 2021 the company saw its biggest production list ever.

Buying Ameritool

With the Ameritool line of products complementing the Covington line, the accessibility serves the needs of a greater audience of customers and people of varying skill levels, according to Emoto.

“These machines are a great way to introduce people to lapidary work! We produce the machines and the pro sanding disc diamond pads in our factory in Idaho,” she said. “The Ameritool grinders and saws are a great introductory machine at a great price.”

Other Additions

Another addition to the Covington Engineering family is a line of ultrasonic drills. The company took over Cutting Edge Solutions in late 2020, which means customers have the opportunity to purchase ultrasonic drills, which are a great tool for quickly cutting holes through stones, added Emoto.

Covington Engineering also purchased a plasma cutter, which has reduced the time and labor involved in creating every piece of equipment the company makes. The company has added CNC mills, lathes, and a press break.

“Each of these items has allowed us to hold tighter tolerances while producing products more quickly and with higher quality materials,” Emoto said. “We have also been able to bring much of the work that used to be done by outside vendors in-house. This has increased accountability while decreasing costs.”

Asked what the founders might think about all these evolutions and expansions, the sentiment is a tremendous sense of pride.

“I think the Covington founders would be most impressed with the company’s ability to adapt to change over the years. The past decade alone has seen the business grow and adapt through countless changes,” according to Emoto.

Saws! Saws! Saws!

One of the long-time standards in the Covington Engineering lineup remains a top seller: saws!

“Saws of all sizes, from 6 inches to 36 inches, are a hot commodity,” Emoto said.

People discovering or rediscovering a love of lapidary during the pandemic hasn’t diminished with a return to pre-pandemic activities.

“People are still interested in the usual equipment such as flat laps, combo units and sanders but this year has definitely been the year for saws,” said Emoto.

Although much has changed from the early days of Covington Engineering’s story, the timeless commitment to creating quality equipment and materials remains at the center of the activities of this industry leader.

“Covington makes equipment that is designed to last a user for decades. We purchase high-quality materials and take great care to maintain tolerances and produce precision-based machinery,” Emoto said. “It is this care and dedication to our work that sets our equipment apart.”

Arrowhead Lapidary Supply

How long has Arrowhead Lapidary Supply used Covington Equipment? What items do you own and use?

We have used Covington equipment since about 2007. We also use a 16-inch saw, little sphere machine, maxi-lap, triple gallon tumbler and a Rociprolap.

What attracted you to Covington machinery and what impresses you most about it?

Quality construction and they are made in the USA. They are sturdily made, and they last a very long time. Also, Covington has great customer service and support on their products.

How does working with Covington machinery help your business? 

They make working on our products less time-consuming.

How did you get started in this line of work? 

It started in 1996 when we were in Montana. We visited a rock shop and saw all the interesting things that were made out of stone. Having an industrial background, we thought it would be fun, and then it made a good business.

Bob’s Jade & Gems – Bob Carman

How long has Bob’s Jade and Gems used Covington Equipment and what items do you own and use?

I have owned my Ameritool equipment for about seven to eight years. I have the universal grinder and the 4-inch trim saw. These machines are dependable and have given me years of enjoyment.

What attracted you to Covington Machinery and what impresses you most? 

The 8-inch grinder is a versatile machine that allows me to make standardized and freeform cabs and polish flat and rounded surfaces. The 4-inch trim saw is very useful for prepping cabs, freeforms, and preforms. The trim saw diamond blades are thin and will save expensive rough material. These compact machines conveniently run on water and take up minimal workbench space.

How does working with Covington machinery help your business? 

What I find challenging is using my imagination to craft new and unique lapidary art forms. With some creativity, these units offer a wide range of design potential.

How did you get started in this line of work? 

I was always interested in rocks and minerals. I learned to do lapidary from a young age. At one of the gem and mineral shows I attended, I bought my first piece of jade. I have since become hooked on collecting and working with jade. Most of the lapidary work I do now is with jade.

MARK BOLICK – ASHEVILLE, NC

How long have you used Covington Equipment? What items do you own and use?

I’ve used Covington equipment for 25 years, from flat lap grinders, to belt sanders, to lathes, and Rociprolaps.

What attracted you to Covington Machinery and what impresses you most? 

I’ve always been impressed with the build quality and customer service from Covington. They understand their equipment and what pieces will work the best for the process you need to accomplish, and you can count on the equipment to do the job. The nice thing about Covington equipment is that it is easy to operate and understand. I don’t have to spend working time trying to figure out how a piece of machinery works — it just works and allows me to increase productivity instead of re-training.

How does working with Covington machinery help your business? 

Having the ability to quickly accomplish things that need to be done opens up new opportunities to discover what we never thought might be possible before. It’s so easy to experiment and test new techniques, that it pushes us to discover new and different ways to manipulate materials with the equipment.

How did you get started in this line of work? 

Once equipment and tools were readily available to achieve an optically flat surface in a home studio, it expanded our ability to move from strictly blown work to a more constructed design.

This sponsored story about lapidary equipment and supplies with Covington Engineering previously appeared in Rock & Gem magazine. Click here to subscribe. 

The post Lapidary Equipment & Supplies – Covington Engineering first appeared on Rock & Gem Magazine.

One enjoyable form of lapidary arts is carving. I’m not talking about a sculpture of the sort that Michelangelo crafted from 10- or 20-foot slabs of marble, nor huge national monuments like the Lincoln Memorial or Mount Rushmore. Rather, think of small sculptures that can fit into the palm of your hand or even smaller pieces that might be incorporated into necklaces or wire-wrapped jewelry.

Carving hard rocks such as agate, jasper, or jade requires fairly expensive tools and machines such as a flexible shaft Foredom or Dremel with diamond bits and carving points, a gem lathe or fixed-shaft spindle, or more. Besides the expense involved in acquiring such machines and their associated bits, carving these harder rocks requires instruction with an experienced mentor and lots of practice.

Also, rough semi-precious gemstones such as jade or lapis lazuli don’t come cheap! Still, the pay-off and reward in the form of a beautiful, gleaming work of art are worth the expense and the effort.

But not all carving requires expensive equipment or materials. For instance, soft-stone carving with commonly available and inexpensive rocks such as alabaster, soapstone, marble, or travertine can be accomplished using simple hand tools. These include knives, scribes, files, sanding boards, various grits of wet-and-soft sandpaper, and polished-infused pieces of leather or cotton flannel.

Whether you opt for hard-stone carving with expensive machinery and high-priced rough stones or for soft-stone carving with hand tools and easily acquired rocks, you will be able to take great pride and satisfaction in transforming somewhat dull, ordinary rocks from nature into shining and dazzling works of art that are wonders to behold!

The post R&G Kids: Gemstone Carving first appeared on Rock & Gem Magazine.

I have been making more cabs lately that have included some features that involve carving techniques. Much of my carving is done with 1” diameter Mizzy silicon carbide wheels which are used dry. The material removal goes rather quickly, but the sanding activity that follows requires quite a bit of tedious work.

Some of the work can be accomplished with rubberized Cratex wheels with various sizes of silicon carbide grit embedded within. The wheels do a good job of smoothing the previously ground surfaces, but there is more precise work that needs to be done. Usually, I use wet or dry silicon carbide sandpaper sheets to finish the sanding job, but as I said, it’s a slow process. The grit on the sandpaper wears down rather quickly, and you need to start with another small piece of sandpaper repeatedly. Overall, it is a slow, tedious process.

Making Discoveries at Shows

A couple of years ago, in June, we went to the Monterey Jade Festival in Monterey, California. It had many dealers from domestic and foreign locations. Many carvers were selling their products and carving tools. A dealer that I frequently see at various shows — Dave Clayton — was selling carving tools. I have purchased many tools from him over the years. His business’ name is Jade Carver.

One time I asked him, “How do carvers smooth rounded or flat surfaces when they are carving?” He responded by showing me some small silicon carbide carving blocks that he uses. They come in various sizes and grits as well as hardness. I bought a set of four with the soft binder. They came in 220, 400, 600 and 1200 grit sizes. Then, I proceeded to bring them home, put them in a drawer, and forget about them until recently.

I started this month’s project, and while I was carving a groove down the center to make a heart shape, I was contemplating how I was going to shape the shoulder of the groove. I wanted it to have a dome shape, and I knew I could grind the shape with my Mizzy wheel, but the result was a rather rough, bumpy surface. As I was dreading the process of sanding the surface with sandpaper, it dawned on me that I had those silicon carbide sanding blocks.

The blocks come in a hard binder used to carve sharp edges or grooves or a soft binder used to smooth curves or domes. After I ground the basic groove and shaped the edges to a dome, I used the 220 soft binder carving block to start the sanding operation. I used this process to get the coarse grinding scratches out and further refine the dome’s shape. I did this activity dry, which I found out later in a phone call with Dave, works better if done wet. These soft blocks quickly ground the surface and helped me get to the desired shape and surface finish. I touched up the piece with the 400 grit and took it to my polishing wheel that quickly brought up the final polish.

Adding Touches of Decorative Carving

I later decided to add some decorative carving from the back in the form of multi-sized

holes that were ground and polished to let a light pattern show through the piece.

If you have any questions about using the carving blocks or anything concerning carving and polishing jade, don’t hesitate to contact Dave at www.jadecarver.com. I found him to be very sharing of his carving knowledge.

The post Bench Tips: Finding a New Tool for Carving first appeared on Rock & Gem Magazine.