Your rock looks to me like Pietersite lacking chatoyance because of the bit of orange. (I’m assuming that if it were chatoyant, you would have said so.) Nellite also can have orange streaks running through it, and is mined near Pietersite, but is too newly-found to date back to your father’s collection, I suspect. ID’ing rocks from photos is always a challenge.
I have a block of what I’m told is sodalite, but instead of having the occasional white streak, it contains yellow crystals throughout, and is “chippy” to work. It is a beautiful block indeed, which is good, as it is likely to remain a block. (-:
Thanks! I have a lot of blocks that will remain blocks. While lapidary is an interest, at nearly 70, my main focus is making jewelry. I do have a lot of fun cutting and polishing, but it is with putting the results into a piece of jewelry that moves me to do so. I will look at the site that you suggest and also research Pietersite. Thanks again…Rob
Work simply. Use fine silver for bezels. And if that doesn’t get half the people to roll their eyes to heaven, try using a nylon rod as your pusher. You can shape it as you like. If you slip and ride over the stone, it will not scratch. I have various diameter rods and usually taper the end and flatten one part to ride along the base plate. Again, it leaves no scratches to add to your labors.
Nearly forgot, I always hit the tip of those pushers ( brass & copper) with a Pillar file of #1 or #2 grit, why so? This will give a “texture finish” to that tip. You don’t want that pusher to slip off of the stone a.k.a. “Whoops!” Further more a 3/16” inch dowel works best for my hand, with a Tapered shaped like a square style of point!
That’s a good idea sram. That nylon is pretty tough. If its a thicker gold bezel that won’t work but taller thin walks it would be good. I like the copper or brass idea also. I’ve gotten good with steel but it feels risky with some gems. I think being in a comfortable position with serious magnification is a must. Makes everything so easy. SD
Yes, I know that aluminum oxide and silicon carbine are all harder than most gemstone materials. That’s why we use them (and diamond) to grind, sand, and polish our stones with. And the silica in pumice is also harder than most of what are considered the softer gemstone materials. So in the context being discussed in the OP’s question it is the grit size of the abrasive that is more relevant than the hardness of the abrasive. Most soft cabbing materials like Turquoise, Lapis, Howlite, Malachite, etc. can be polished straight from a 600 grit sanding. So if there is a slip when cleaning up a setting with a soft stone, and the stone gets rubbed, light scratches from the F and FX Craytex wheels are so fine that they should fairly easily be buffed out of the softer cabbing materials with ZAM or Fabulustre on a muslin wheel.
As for the facet junctions which you mentioned, I wouldn’t attempt to use Craytex wheels on a setting with a faceted stone regardless of the stones hardness. But I don’t think that faceted stone setting was what the OP was asking about, and wasn’t what I was referring to when suggesting using the Cratex wheels. I was using the Craytex wheels on cab prong settings but realize that wasn’t stated clearly enough.
And I choose to use lacquer thinner over acetone because lacquer thinner is a little more powerful solvent than acetone. Lacquer thinner will break down and leach dye more quickly (assuming the dye isn’t mixed and set with a hardening agent), and will more likely cause a more colorfast type dye to leach better than acetone will. Also lacquer thinner will evaporate without leaving a residue equally as well as acetone. But I do see your point for those doing contract work for others needing to be more cautious when testing a customer’s or dealer’s stone for dye or wax.
For what it’s worth, I use a chasing hammer and steel punch for setting every single bezel I do (yes, this includes opals). No real reason other than I’m just comfortable using it and I like the predictability of it. I used to use brass, but didn’t care for the lack of feedback I felt. With steel, there’s a distinctive sound the hammer makes when it is moving the metal vs already against the stone and I find that to be the biggest help of all.
Like Erich, I use a chasing hammer and steel punch for most bezel setting, and I’ll add especially for soft and delicate stones like opal. I get much better control with a hammer and punch than with a powered hammer (air is my preferred power source when I use it) or a pusher or burnisher. If the punch is sufficiently polished, properly shaped and used properly, it can leave the bezel smooth enough it needs only a touch of rouge to finish.
I never use Cratex or any other type of abrasive wheel to finish the bezel of a soft stone. Or get one anywhere near a delicate stone for any purpose for that matter. Even if the stone is undamaged by the use of a wheel, the dust they leave behind can do more damage to a stone than the wheel itself when wiped away with a dirty finger .Cratex dust on a fingertip can seriously scratch a tanzanite or demantoid garnet in a heartbeat.
Nothing beats a radiused, sharp and polished #42 flat bottom graver for cleaning up bezels near soft stones. The finish usually doesn’t even need to be touched with rouge if the graver is polished well enough, and the top edge of the bezel stays nice and crisp. Abrasive wheels just round the top edge and expose the stone to greatly increased risk of damage. They also can’t get into corners or smooth any bezel that’s too far away from a round or oval shape without causing it to come out wobbly.
Dave!
Finally someone tells it like it is! You are using a Flat Graver… congratulations on you choice of tools. My personal choice of a Flat would be a #40.
But whichever you use, you should be comfortable with it. If it works and with no stress or struggle, if it gives you great results, why not?
So happy you’re using & telling others about your findings… Happy Holidays!
Larry Cashatt,
I recently posted and no one responded.
On Minddat.orghttp://Minddat.org pumice is listed as volcanic
glass, mohs hardness of 5-6.5. No silica in
pumice.
Silica is listed at 8.
Silicon carbide at 9+
Aluminum oxide is a 9.
My question was in reference to something
Gerry said, that was not answered.
How can pumice, volcanic glass,
5-6.5 scratch quartz at 8?
Has anyone using pumice caused damage
to any gem that is 8 or above?
Pumice can cause damage to soft stones,
usually fixed with felt wheels and Zam.
I had bad luck 40 years ago with Cratex,
rubber embedded with silicon carbide
before I understood what they were made
of, I never used them again after causing
damage to gems.
My experience, once a gem is damaged
during setting, remove, sand and polish,
or replace.
I do lapidary work, I have never been
successful at repairing damage caused
during setting without removal that
met my standard.
The exception is repolishing the table
of a very lightly scratched faceted gem
using my faceting machine, at the
sacrifice of losing part of the star facets.
Larry.
First of all, I’m very busy writing 3 intensely difficult essays. I just scan over the emails!
“I avoid touching any stone with any pumice wheel.” These wheels will never get near any stone! I’m not into looking up the chemical compounds of these wheels. I leave information for others to search.
All I know is these wheels came from volcanoes.
Many setters I know don’t give ‘rats tusch’ how they are made. Just as long as they work… All I use are the #180 & #1,000 grit!
BTW, I’ve been taking very difficult photographs at 175 magnification, just for Ganoksin!
If you think I have been slow in returning inquiries, so sorry…
Gerry! On my Teaching iPhone!
Here are a couple photos of the business end of my favorite #42. It’s hard to see, but the radius refers to the shape of the belly, or bottom at the cutting edge. It’s not flat, the leading 2mm or so is curved from flat to about a 10 degree angle at the cutting edge. The face or top of the graver is sharpened at about a 50 degree angle to the flat, so the cutting edge is somewhere around 60 degrees. I polish it with a fine ruby stone with the graver chucked up in a GRS sharpening jig.
The bottom photos show a couple of the bezels and channels that I cut and finished with it…
Re: sramsdell17h
Work simply. Use fine silver for bezels. And if that doesn’t get half the people to roll their eyes to heaven, try using a nylon rod as your pusher. You can shape it as you like. If you slip and ride over the stone, it will not scratch. I have various diameter rods and usually taper the end and flatten one part to ride along the base plate. Again, it leaves no scratches to add to your labors.
I have used the beheaded stems of clear toothbrush handles. Cheap and shape-able. Good handles make to take teeth cleaning pressure and more.
???
I believe you misread Richard Hart’s post in which he begins it by addressing me by name, but latter references you, as being a post written by me. It wasn’t.
The link to Mindat you posted isn’t working for me but I believe you must have either stumbled onto a page with erroneous information or misread it. Pumice is defined in Mindat’s words as “Glassy, highly vesicular, mostly silicic igneous rocks.” https://www.mindat.org/min-48576.html
The term silicic means “rich in silica”. And silica has a hardness of 7 on the Mohs scale, not 8. Download Our Particle Hardness Table - Prater Industries
The hardness of pumice varies from source to source. While the mineral composition of pumice tests 5 - 6.5 on the Mohs hardness scale, it does contain silica particles which are Mohs hardness 7. And the higher the silica content of any given pumice, the harder the overall composition will be.
But it is not necessary for one material to be harder than another material in order to abrade it. For example, one could etch a piece of glass (with a Mohs hardness of 6) using granules of any one of the minerals from the five lower Mohs scale levels. It’s just that it would take longer to do so with talc granules (Mohs 1) than it would with calcite granules (Mohs 3) of the same particle size. Also abrasiveness is effected by the velocity of, and pressure being applied to the use. Steel can be cut with high velocity water jets. Any dentist will tell you that people who use excessive pressure chewing show more wear on their teeth., etc… So to answer your question if pumice can damage a stone with a hardness of Mohs 8 the answer is yes it can.
But for the sake of our discussion the particle size of a commercial abrasive being used on a stone softer than the abrasive itself is just as relevant, if not more so, than particle hardness. While a SC particle will more easily cut a scratch in a softer material than a silica particle will, a scratch is still a scratch. And all other factors being equal (speed, pressure, etc.) the size of that scratch is largely influenced by the particle size of the abrasive material. Obviously 180 grit abrasive particles can cut much deeper and wider scratches than 600 grit abrasive particles can under the same circumstances. (Craytex makes wheels in 4 different grit textures). And the deeper and wider the scratches are, the more difficult they are to remove. Light scratches from a fine abrasive like 600 grit can usually be buffed out of soft materials with ZAM or Fabulustre on a muslin (Not Felt) wheel as long as the abraded area isn’t dug in too deep into the stone’s surface. Muslin wheels can get into close tight corners, and closer to seams, better than felt can. With harder gemstone materials scratches can not be buffed out in this way. But even on the softer gemstone materials, and even with finer abrasive sizes, if the abraded area has been dug in too deep into the stone’s surface then yes the stone will have to be removed t to be repaired.
If you’re having problems controlling rotary tools while cleaning up prongs or bezels, and don’t want to give up abrasives and try one of the techniques others have suggested, then you could always use emery sticks for better control.
Beautiful work! Thanks for the sharing those pics!
On a side note to any others that may be interested, the radius referred to here is also known as a “heel” in engraving circles. Just another term for anyone that comes across it.
