Heart of Stone Studio Blog

A Review of the Denver Gem and Mineral Show

   The end of summer has been really busy for me, and Fall got off to a good start with my trip to the Denver Gem and Mineral Show, where I was buying stones for my website, www.heartofstonestudio.com. Every time I mention this show, which is held annually in mid-September, people ask how it compares to the Tucson show, and is it worth going to? This is my second year going, and I'd like to share my thoughts with you about it.

   The Denver show can't really compare with the February Tucson show--it's a fraction of the size, held in six or seven venues instead of Tucson's dozens. Having said that, I think that it still has merit. I'm finding that several of my suppliers now make it a point to set up in Denver as well as Tucson, so it's a worthwhile trip for me to visit them and stock up mid-year between Tucson shows.

   Let me tell you a little bit about the shows. Five of the six venues are within a mile of one another, and all of these are located in an industrialized area just north of the junction of interstates 70 and 25, which is about ten miles north of downtown Denver. Two of the shows are at hotels--the Holiday Inn and Best Western (although the sign at the top of the hotel says Quality Inn) which are within walking distance of each other. These two shows feature minerals rather than gemstones or finished jewelry, although a small percentage of those are available. Here, international dealers rent rooms and fill them with spectacular (and pricey) collectible mineral specimens. Some rough material is also obtainable. These shows are the first to open during that week. I suggest that if you're driving, you get there either a half-hour before the 10am opening time, or after 4pm, because the parking situation is horrific. These shows don't require any registration, and as far as I know, they are open to the public. Dealers will sell at retail prices, but will usually give wholesale discounts to qualified buyers who bring evidence of their resale tax status.

   Three other shows are ten blocks away at the Denver Merchandise Mart. The Mart is a huge complex, and unless you know where you're going, the shows are somewhat difficult to find. The upside is that parking is relatively plentiful.

   Toward the rear on the west side of the Mart complex is the Pavilion building, the site of the International Gem Show. This wholesale show starts a couple of days after the mineral shows, and the noontime opening was crowded and disorganized this year. The show is a mix of mostly finished jewelry, some cabochons, a few dealers in faceted gems, and some Asian dealers selling bead strands. It's not a huge show, but it does have a decent variety.

   The day after the Gem show starts, the Fossil Show opens at the Mart's Plaza area, which is on the opposite (east) side of the complex. This was the first year I attended the Fossil Show, and I was just blown away by it. Tucson has fossil venues, but to me they seemed more spread out and haphazard, whereas Denver's Fossil Show appeared large, well-organized, and in an attractive setting. Interspersed among the booths were full fossil skeletons of a 12-foot tall cave bear, a baby tricerotops, and several others. You could find 3-D trilobites complete with waving antennae, ammonites the size of hubcaps, bug-filled amber, and hundreds of fossil fish, including one whose bony head was turned as if to swim out of the limestone background. It was more fun than a museum, because you could buy the specimens if you wanted to.

   As I entered the fossil show, which is open to the public, I was dismayed to see a dozen schoolbuses disgorging hundreds of grade-school kids, but the show was so large they really didn't make viewing difficult. What's more, it was neat to see a 15-foot-long duck-billed dino skeleton walking among the crowds, bony tail waving above everyone's heads--It was a clever reproduction made by a dinosaur educator who straps himself into a harness inside the pelvis and literally makes the creature "come alive" to schoolchildren. If you and/or your kids are fossil aficianados and can get to Denver during this time of year, the fossil show is highly recommended. Plus, interspersed among the fossils were booths with slabs, cabs, carved stone boxes, mineral sculptures and art pieces. This was a very big, and very good show.

   Across the street from the Mart was a small miner's show that specialized in cut slabs and rough material. There were two other shows that I didn't have time to attend. One was the weekend Gem and Mineral show which was open to the public. Another was a bead show in a venue close to the airport. But that was pretty much it.

    In all, I would consider Denver a smaller but representative taste of Tucson. Plus, it is more manageable than the crowds, crammed hotels, and general insanity of the Tucson show. If you want to try the Denver shows next year and you're not planning to spend much time downtown, I would recommend staying to the north of the venues, preferably in or near the suburb of Westminster, which is literally a ten-minute drive (traffic permitting) from the venues and about 40 minutes from the airport. Motel accomodations are also available a few miles outside the Denver airport, but the drive in to the venues is longer. Parking is easiest at the Merchandise Mart, and a shuttle is available from there to the other locations.

   

 

   

   

The importance of cut in faceted stones

      Both diamonds and colored stones have something in common, and that's the importance of cut. An excellently-cut stone can dazzle the eye with light and sparkle, and distract from weaknesses such as inclusions and less-than-ideal color. Conversely, a poorly-cut stone is a sad thing, as though the material couldn’t live up to its potential.

     When I first began shopping for faceted stones, I really tried to carefully look at what I was purchasing. But it's hard: Try standing in front of a dealer's booth filled with gems, the halogen lights beating down on you, other shoppers jostling you and trying to get waited on, and you will soon realize that you have to make quick decisions on the quality of a stone. I made some mistakes and learned pretty quickly, and honed my skills by looking at hundreds, even thousands of faceted stones.

    What I came away with was the impression of how much drek there is out there, yet people keep buying it. I am especially disheartened by how bad much of the cutting is, especially with smaller stones. You would think that it's relatively simple, once you've learned how to cut a gemstone, to do it consistently and symmetrically, leaving out the bad inclusions and working to bring out the beauty of the material. Nope.

     One confounding problem is weight. Diamonds and colored stones are sold by weight, not by size or shape. A hundredth of a carat left on a stone may not seem like much, but multiplied by thousands, even tens of thousands of stones, that weight can add up to big additional profits. The problem is, that added weight has to go somewhere, and it might go into making the stone deeper than it should be for an ideal cut, or its girdle thicker, or the crown (top) higher or broader. Working to include that extra weight results a slight but definite change in the proportions of the stone, which in turn affects how light enters and bounces around before leaving to greet the viewer's eye.

     Another problem is perceived value. There is pressure to squeeze the last iota out of a piece of gem rough, because this is not material that anyone likes to waste. Regularly “editing out” and tossing material with inclusions and other imperfections would drastically reduce the yield. However, sometimes the problems are so noticeable that a cutter can’t possibly include them, so he or she is forced to “work around” a serious flaw, which again might alter the proportions of the finished stone.

     The third thing to keep in mind is that not all gemstones are cut by experts. Yes, larger diamonds are, but some less-valuable diamonds and many, many smaller colored stones are cut by beginners. Do I hear a gasp? Well, they have to start somewhere. And unfortunately, many student efforts in gem-producing regions don’t end up on the rubbish heap. Most often, they are tucked into lots, which are larger quantities of stones made available to wholesale gem dealers. Back when I started as a jeweler, I purchased some lots of faceted stones, which seemed like great deals at the time. When I got them home, I found that 10-20% of each lot was composed of really fine gems, about half of them were OK—eye-clean, and the remaining 30 to 40% were what I would call trash—badly flawed and/or poorly cut. By the time I had sorted out only the good stones, my per-stone price had increased dramatically. I set the “trash” stones aside for students to use for practice, but some dealers will go ahead and put them into lower-priced jewelry.

     Now, I don’t want to give the impression that gem miners or cutters or dealers are unscrupulous people “out to get” the consumer. I prefer to look at it this way: Natural gemstones can be a crapshoot, from the minute someone gambles on locating a mine, to whether the inside of a piece of rough is as great as it seems on the outside, to whether a stone will hold together during faceting, through all the other risks and pitfalls involved with cutting, transporting, and marketing stones. This element of risk continues right on down to the consumer.

     Generally speaking, my sense is that the attitude among this world of gem dealers is: If you know what to look for, they can provide you with excellent gems. However, if you don’t know what you’re doing, they are not going to go out of their way to enlighten you. Never has the motto, “Let the buyer beware” applied so aptly as here.

     On my Heart of Stone Studio website, I do my utmost to present really top-quality cabochons, faceted gems, and drusies. If the stone is less than perfect, I disclose that right up front. Not every retailer will do that, but it has really proved worthwhile for me in return business because my customers know they can trust me. And that’s why I’m writing this blog, because I think we can all benefit from being better educated about gemstones. I’m learning all the time!

In my next post, I’ll try to explain how I evaluate the cut of a faceted stone.

More thoughts on PMC settings for stones

        PMC expert Bridgette Rallo has responded to my idea about using prefabricated faceted stone settings and incorporating them into a PMC design:

Prong bezels and bezel cups work well for a lot of different stones and can even be pushed a bit to fit stones that are close to the calibrated size. Be very careful with prong settings, though. Make sure that you have good contact between the stone and each prong. Dichroic glass is a wonderful alternative to a natural stone,

especially when it's an accent stone. Using a glass cab "dot" eliminates the need for two bezels. This saves a lot of space in your design. It is really worth it, after all is said and done, to learn how to make bezels for natural stones. There's a big learning curve but nothing comes close to a custom setting for a gorgeous freeform cabochon.

   

If any readers have had any experience with this, please write in and I'll add it to the discussion.

Restrictions on firing gemstones in PMC

     My previous posting with Rio Grande's chart on survivability of gemstones when exposed to the heat of a PMC firing has sparked a response from Bridgette Rallo of The Greenwoods Studio. Ms. Rallo is a jeweler, educator, Heart of Stone Studio professional customer, and expert on PMC. She says:

You know, Judy, I really question exactly how the stones they fired at Rio looked after they came out of the kiln...I have never heard of a stone that can survive a firing at the temperatures needed for PMC 3, never mind PMC+ or Standard. The only exception is calibrated hematite, which can take 1100 degrees for 30 minutes. I had an assistant who put a bezel into the kiln without removing a Mexican lace agate and I noticed it after about 5 minutes...the temp had reached 1030 degrees and I was able to salvage the stone but it did darken quite a bit. When Rio says the stone survived, they mean it didn't blow up in the kiln. But I will guarantee you that it had considerable color change. I get color change even on pieces of sea glass, which is why I make pre-fired bezels for them now.

    So, it appears that great care and discretion needs to be practiced when planning to include gemstones in any PMC firing. I am listing some other approaches worth considering:

--Firing only synthetic gemstones and CZs (Cubic Zirconias), although there is no absolute guarantee that these stones won’t change color or at least darken, in the kiln.

--Pressing the gem into plasticine to make a mold, then filling that mold with plaster of paris, popping it out when dry, and then substituting that for the gemstone during firing. After firing, carefully drill or chip out the plaster and you have an automatic seat for the stone. (I suggest drilling a hole through the bottom of the metal seat so that light gets into the stone from the back.) However, unless you’ve set up a bezel or other way to trap the stone in place, you’d have to glue it in, something that you wouldn’t want to do with an expensive stone because it is certain that it would eventually fall out.

--A third option that I’ve thought of but don’t know if it would work with PMC, is to purchase a pre-made prong setting (that fits the stone) and fire the bottom of it right into the clay of the piece, making sure that a bit of clay anchors the setting in permanently. Then you can set your gemstone safely into the setting after firing. Might be worth experimenting with...Any other comments or tips are welcome.

Next posting, my thoughts about the importance of cut in faceted gemstones…

Gemstone suitability for use in PMC

      Now that I have begun to offer melee diamonds and semi-precious colored gemstones on my website, Heart of Stone Studio, people have written to ask which gemstones can be used in firing precious metal clay. Genuine diamonds can, of course, and CZs (cubic zirconias) as well as synthetic stones, but real colored gemstones are another matter. For one thing, if the stone contains any major inclusions that heat and cool at a different rate than the surrounding stone, they can cause the stone to crack or explode. Or, a small fracture, when heated, can expand to become a big, damaging fracture. The other possibility is that the crystalline structure of the gem does not lend itself to firing. Regardless the reason, the result is a double mess--a damaged stone that's also locked in place in your piece.

     So, I called the folks at Rio Grande, a large and reputable jewelry supplier out of Albuquerque, NM. Their research department experimented with firing a variety of different stones in two types of PMC.  I've made up a chart of their findings that I hope the PMC enthusiasts will find useful:

Gem Suitability for Use in PMC	Information provided by Rio Grande
Gemstone	Dry Fire	PMC 3
Chrome Diopside	not available	Survived
Garnet: Almadine	Survived	Survived
Garnet: Pyrope	Survived	Survived
Garnet: Rhodalite	Survived	Survived
Garnet: Tsavorite	not available	Survived
Hematite	not available	Survived
Moonstone	Survived	Survived
Peridot	Survived	Survived
Black Star Sapphire	Survived	Survived
Tourmaline	Survived = iffy	Damaged = iffy
Denim Lapis	Survived = iffy	Damaged = iffy
Lapis Lazuli	Damaged	Damaged
DO NOT TRY THESE STONES
Amethyst
Aquamarine
Black Onyx
Blue Topaz
Blue Misty Chaldecony
Cameo
Carnelian
Citrine
Iolite
Jadeite
Malachite
Mexican Fire Opal
Rhodochrosite
Rose Quartz
Tiger Eye
Turquoise ------------------------------- Any information that PMC experts might like to add would be welcomed.

Evaluating diamonds

      Diamonds are such a mystery to people. They are beautiful, sparkly, extremely expensive, and many people own at least one, yet understanding how the experts assign them value seems to be some sort of inside knowledge that most of us feel excluded from. And, actually, that's somewhat the truth--Certified gemologists, diamond dealers, and jewelry-store owners have their own techniques, their own terminology, their own tests, and we pretty much have to take their word that they know what they're talking about. But then, isn't that true of many professions? That special knowledge is what makes the true insider, and allows one professional to recognize another instantly.

      Well, I'd like to share some insider secrets to help you to understand diamonds. The biggest and best-kept secret is: They may be gorgeous, but they're far from perfect. In fact, if you swept your garage floor and dumped the dustpan contents into a big 55-gallon drum of jello, stirred it up and then chilled it solid, that's pretty much how much of the world's diamond rough would look--filled with bits and pieces of things. Of course, there are those renowned "fabulous finds"--large chunks of clear material, but those are very rare.

     So the bottom line is, the majority of diamonds have "stuff" in them--bits of other material, tiny fractures, discolorations, pieces of diamond crystal grown in a different direction, little chips, etc. etc. This should actually not be surprising, because diamonds are a natural mineral material, and natural material of any type is seldom perfect. That's what makes it natural, after all. Master cutters can cut around the worst stuff, but diamonds are so precious that each and every bit of rough that can be used, is used. The poorest pieces are slated for industrial use, because there, only hardness counts, not clarity or color. But think about it--other than gold and platinum, what materials do you know of where even their dust is valuable?

     OK, this train of thought leads to certain important truths: One is, the larger the diamond, the more difficult it is to find one without any flaws, and the more precious that stone is going to be. Many people dream of getting a flawless diamond, but the reality is, if you could ever afford a truly flawless diamond (flawless inside and out), you could never wear it. It would have to sit forever in the darkness of a bank vault, because one bump of your hand, one tiny nick, and it's no longer flawless. In fact, the few truly flawless large diamonds in existence aren't even set in jewelry. It's too much of a risk. And, to me, the very worst thing about such perfection in diamonds is that it can now be easily duplicated by synthetic diamonds. If they can grow "perfect" diamonds in the lab, I tend to think that detracts from the allure of a flawless genuine diamond.

    The second "secret truth" is that internal flaws (which diamond experts never never call flaws or imperfections; that's too negative, so they call them inclusions), can be, in small amounts, a good thing. You know how on the TV commercials, the snobby diamond expert intones that "no two diamonds are alike," implying that this uniqueness is what adds to their value? Well, you know HOW they can tell that no two diamonds are alike? Yep, by their flaws--sorry, inclusions. If you were to cut the dirty jello in the 55-gallon drum up into ice-cube-sized pieces, every single piece would be unique, too.

    What gemologists do when they inspect a diamond for certification, is take a finished diamond and put it under a microscope. They look at it from the top, the bottom, and the side. On the desk next to the scope they have a drawing of each view of that diamond with all the facets outlined, and they map every single inclusion, every nick, every thing and its exact location in a special code that they mark onto the drawing. They also evaluate its color, and its cut. When they are done, they have noted every single characteristic of that stone in such a way that it's almost like a fingerprint--an absolutely unique picture of that stone. That's important and valuable for two major reasons:

   1. It proves that that diamond is not a synthetic produced in a lab in four days, but a real gemstone produced by mother earth over hundreds of millions of years.

   2. It protects the owner of the diamond. Without a diamond certificate, you have no way of proving that the diamond ring you brought in for resizing still contains those same diamonds when you get the ring back a week later. (That's another reason why, as a buyer, you always want to build a good relationship with a reputable jeweler whom you can trust.)

    So I hope these insights are getting you to think differently about diamonds. More in my next blog. And, just to let you know--I am now selling small, incredibly gorgeous diamonds on my website, Heart of Stone Studio.

      

care and cleaning of drusies

     To effectively clean drusies, it's best to remember what they are--Essentially, they are groups of tiny crystals that grew out of a mineral matrix. Some drusies, like those of azurite, are really crumbly and unstable, which is why I won't sell them on my website. They would fall apart at the slightest touch. Others, like quartz drusies, are both hard and relatively tough, but even then, they're not damage-proof. You have to picture the individual crystals sitting like little teeth in the bone of your jaw--a hard enough knock, or rough abrasion, or lateral pressure back and forth, and that "tooth" can come out of its socket. A few missing crystals, with a dark matrix showing beneath, can detract from the look of a druzy cabochon. That's why proper cleaning and storage is so important.

      First, let's start with coated drusies--titanium, gold, platinum, etc. The coating is very thin--it starts out in vapor form and attaches to the quartz crystals in a vacuum. With proper care, the coating should never wear off. To ensure the full life of a coated druzy, I never put it in a sonic cleaner. Instead, this is how I clean it:

     I make a bath of warm soapy water. I use a dishwashing liquid without any moisturizers in it, something straight like Dawn or even liquid Dial soap. Various jewelry suppliers sell special jeweler's cleaning solution which is also good. I swirl the druzy through the water, or, if it's especially dirty, I let it soak for ten minutes. I don't use brushes on coated stones--the abrasion isn't worth the risk. 

     Next, I rinse in distilled water. Regular tap water has mineral deposits that dull the sparkle of the druzy. If you're doing more than one piece, fill a plastic container with some of the distilled water and place the cleaned drusies in it. Again, you can swirl the stones around or let them sit for several minutes. Try to match the temperature of the soapy water and the rinse water--You don't want to thermal shock the stone by washing it in hot water and plunging it into a cold rinse.

    The next step: Remove the stone and place it right side up on a paper towel, and pat the back and sides of the stone to remove excess water. Don't place the paper towel on the front of the stone because the crystals will snag small fibers from the towel.

     Immediately afterwards, using a hair dryer set on a warm or cool (but not hot) setting, blow dry the stone. I usually hold the stone in one hand and move it around as I hold the dryer in the other hand, rather than trying to dry the stones while they're lying on the paper towel--things blow away that way.

     Clean natural drusies the same way as coated ones. In the case of natural quartz drusies, I get bold enough to use a soft toothbrush and gently brush it across the druzy crystals, especially in areas that might be discolored. Rinse and dry as described above. With other natural drusies, such as pink cobalto calcite and hemimorphite zinc, I refrain from brushing the crystals.

    The cleaning method described above also works for drusies set into finished jewelry. A quick cleaning does wonders to revitalize the sparkle and color in a druzy piece. The only thing you might want to avoid placing into soapy water are pieces containing pearls.

    The safest storage for a piece of jewelry with druzy in it is sequestered from other jewelry pieces that can bump against it. I recommend storing it in a little plastic bag and/or its own storage box.

     Drusies may look delicate, but if cared for properly, most of them are tough enough to last forever in pendants, earrings, bolas, and dressy bracelets that aren't worn often. As always, I recommend that people avoid setting them in heavy-wear items such as rings or belt buckles. You can see drusies in every color of the rainbow on my website: heartofstonestudio.com

Sonic cleaners

    I've used sonic cleaners in the past and have always passed up buying one for myself. "Too much money that I can better spend someplace else," I would tell myself. So I spent years laboriously cleaning off stones and jewelry by hand. Maybe not such a wise decision, considering the time I wasted.

    Finally, I found a sonic cleaner on sale at the Tucson gem show and made the investment. Of course, this is not one of those plastic jobbies that you can buy in the drugstore, but a real one, made of brushed stainless steel. Sonic cleaners are basically little tubs into which you put soapy water, and when you turn them on, they bombard the stones with soundwaves, which knock loose stubborn dirt particles. They really do get faceted stones and jewelry much cleaner than by hand. It's always nice to clean friends' diamond rings for them, because they come out sparkling.

   Sonic cleaners do have pros and cons, however. Another pro, in addition to how sparkling they get faceted stones, is that they are very useful in removing greasy buffing compounds when you're in the process of polishing up a metal jewelry piece you've made. They also loosen gummy glues and tapes that might be attached to the backs of cabochons. (These tasks are made much easier if you use a sonic cleaner model that also heats up the liquid in the tub.) And, even with a small version, you can clean quite a few pieces of jewelry, or gems, at one time. Most items clean within only 5 to 10 minutes.

   The main drawback to using sonic cleaning machines is that you can't put delicate things into them such as opals, pearls, or soft stones such as turquoise. And I would not sonic clean drusies--although its matrix might well keep the stone together, the sound waves might force some of the crystals to spall off, and you'd be left with a stone with noticeable "holes" in its surface. Also, I recommend against the sonic cleaning of coated drusies--that coating is thin and you don't want to abrade it with sound waves. In addition, you absolutely should NOT sonic clean any stone that has fractures running through it--the sound waves can cause the stone to break apart. I've got some lovely Laboradorite cabs that were perfect going in, but because they contained hidden fractures, they came out in pieces. Lastly, you don't want to bombard your fingers with these waves, so be sure to turn off the machine before you reach in to pick up your piece.

  On the positive side, diamonds, most transparent faceted colored stones, most cabs that are hard and without fractures, and most gold, platinum, and sterling silver jewelry responds well to sonic cleaning. If you are interested, I recommend investing in a professional one that you can buy from a jeweler's supply. You don't have to get a big one--I spent less than $100 for mine. I also recommend investing in one that has a heater so that you can warm up the water, which helps as well.

   My bottom line on sonic cleaners is that they can be a big time saver, especially for cleaning jewelry pieces with lots of nooks and crannies. But when in doubt, I suggest that you insure the safety of the piece or stone by turning off the sonic cleaner and doing it by hand.

   If any other jewelers out there have input on sonic cleaners, I'd sure like to hear from you. If you'd like to see some really beautiful--and clean--stones, stop by my website: www.heartofstonestudio.com

next....cleaning drusies

    

How to clean gemstones

  Sorry to be quiet so long; I've been traveling and most recently, publishing one hundred new gemstones to my Heart of Stone Studio.com website. But now I'm back and thinking of things of interest to share with you.

  Something that I thought would be helpful is to talk about cleaning and storing gemstones. I handle literally thousands of stones a year, and it is important for the stones to look their best when they arrive in my customers' mailboxes. Here are the ways that I clean gemstones:

  For cleaning cabochons, people use many different things. I've heard of people using Windex, ammonia, and a variety of glass cleaners. My choice is something I learned from a lapidarist: denatured alchohol. This is not rubbing alcohol or any alcohol that you can buy off the shelf. Unlike rubbing alcohol, denatured alcohol doesn't contain any extra ingredients, and the concentration of real alchohol is much higher. The only place I can get it is from a pharmacy, sometimes by special order. It is more expensive than rubbing alcohol, but is still affordable and a bottle lasts quite a while, as long as you don't let it sit open for more than a few minutes at a time (it evaporates quickly if exposed to air). I order two bottles at once; as long as the bottle is kept tightly closed, it will keep for months. Be sure to store it away from heat, direct sunlight, or open flames.

   The denatured alcohol works great on agates, jaspers--any dense, non-organically-based stone. It cleans off glue, tape, dirt, grease, fingerprints, and reveals any shine that might be hidden under grime. If you have a stone with lots of gunk on the back, you can put the denatured alcohol on a 3M green plastic scouring pad and use that to get things clean.

     For the fronts of stone, I wouldn't recommend using the scouring pad--you don't want to risk scratching areas of the stone that might be softer. Most people grab a paper towel or a soft cotton cloth, but I've found that both of these leave a ton of lint behind (which shows up in my closeup photographs). Instead, I use microfiber cloths, which leave very little lint.  Microfiber cloths are sold in the cleaning section of most large supermarkets. After they get dirty, these can be washed, although they should be washed separately to avoid picking up lint from other clothing.

      Now I might be overly protective, but I prefer not to use the denatured alcohol on corals, fossils, turquoise, and copper fire bricks. For these stones, I like to use a glass cleaner called Cinch. It seems to contain components that clean nicely and leave a shiny surface. I also use Cinch for cleaning my fused glass. After cleaning, I store the cabs in little plastic bags.

     One caveat of denatured alcohol--you don't want to use it anywhere near pearls. In fact, you don't want to use any strong cleaner near pearls. That would really damage them.

      Next, sonic cleaners....

Cabochons front to back

       One of the best things about running a website is that I get to dialogue with my customers, mostly by e-mail, but occasionally by phone, too. Sometimes it's a very educational experience for me.

     An issue came up this past week: A customer bought a stone that she thought was beautiful, but she couldn't use it because the back wasn't polished. Of course she was able to return it to me, but it made me realize something: "Tradition" is shifting yet again in the stone world. Here's what I mean:

    As long as I can remember, cabochons generally were never polished in the back. A lapidarist would slice a  1/4" thick slab from a chunk of rough, draw the outline of the stones he wanted to cut onto the slab, and then cut them out. Then he would meticulously grind away the excess and form the piece into a typical rounded cabochon with a nice smooth, graduated surface. But his work was far from over--He still had to polish the stone. This involved laboriously working the stone through a series of finer and finer polishing grits (washing one polishing compound off before applying the next), until he could bring it to a high shine.

     If you consider all the labor that went into producing one single cabochon, you would realize that polishing the back of the stone was not cost-effective for the cutter--After all, the stone would be bezel-set, and once that was done, no one would ever see the back of the cab, anyway. So why waste time (and thus money)polishing the back? In fact, one pretty sure way to tell a stone is hand-carved and polished is by the back.

    But as I learned from my customer, times are changing. In the past few years, wire-wrapping has come into its own as a way to set stones. Talented wire-wrappers are doing really fine, artistic work that can be more individualized and graceful than traditional bezel-setting. Problem is: Now you can see the backs of the stones, and they have to be polished. Strangely enough, this really didn't dawn on me until I corresponded with my customer this week.

    I still carry a few stones that don't have polished backs. And I will continue to carry them for a couple of reasons: First and foremost, they are really beautiful. Second, they were cut by traditional lapidary artists, and I want to continue to show support for this art form. However, as I post these types of stones to the website in the future, I will mention that they don't have polished backs, so the wire-wrappers out there will know.

    This doesn't mean, of course, that all stones with polished backs are not hand-crafted. In most cases, they are. If the entire stone has been polished by hand, then most likely that extra effort will be reflected in the cost.

    But another new lapidary development is that some of the top cutters are designing, carving, and shaping their cabs by hand, and then polishing them by machine. They do this by putting the stones in rotary tumblers, along with polishing compound. They have to rotate the stones among several different tumblers, each with a successively finer grit polishing media, and the whole process can take several weeks, with the tumblers running 24 hours a day. But they can put several dozen stones in a tumbler at one time, instead of working on them individually. It saves them time, and keeps the cost down for hand-cut stones that are polished on both sides.

     There are some drawbacks to this process: The cutter can't really mix stones of varying hardnesses, because the harder ones will scratch and possibly break the softer ones. Also, with all that tumbling, one or two stones per batch will most likely be lost due to breakage. Also, not all species of stones lend themselves to tumbling.

      But the biggest challenge is that 99 percent of tumbling media can't bring out the same high level of shine as individual polishing. Most lapidarists who have tried it, have failed. Fortunately, I've been lucky enough to find a couple of lapidarists who are not only artists at cutting, but who also have discovered the right recipes for tumbling media, as well as the right techniques, that will bring out that fantastic high shine. And let me tell you, those media recipes and tumbling techniques are closely-guarded secrets. They wouldn't even give me a hint. That's OK, as long as they keep selling me their fabulous stones, so I can make them available to you, I won't complain.

    So those are the ins and outs, front to back, about polishing cabochons. Perhaps you'll see yours with new eyes now. Oh, and if you are a wire-wrapper and need to ensure that all your stones are fully polished, please write me a little note to that effect when you check out from my website, OK? (www.heartofstonestudio.com) That way I can make sure you get the right stones for your needs.