|
|
Post by Tweetiepy on Mar 17, 2005 12:44:50 GMT -5
Not that I'd be able to ever get any equipment to cab or facet... but how does faceting work? - I know that you cut little slices on an angle so that the light hits the stone - but I guess my question is this... If you have a rock - let's say an emerald since everyone's tumbling them lately - it's still a rock, the outside may become shiny & mirror-like by tumbling but the inside is still like a rock - solid & non-see-through - how does faceting make it look more like glass? or is the way it's cut hide the rocklike inside of the stone?  Since I've seen rubies, garnets, emeralds & all these precious stones in their natural state (how does anyone distinguish these things from normal rocks?) I've been wondering about stuff like this. |
|
chassroc
Cave Dweller 
Rocks are abundant when you have rocktumblinghobby pals
Member since January 2005
Posts: 3,586
|
Post by chassroc on Mar 17, 2005 13:10:31 GMT -5
Hello Tweety,
That's a good question. I'm not a faceter either but I've looked at some fateing machines and I believe I know how it works.
First you need a plan for the final result, . e.g., "I'm going to make a brilliant cut" on this stone. This determines how many facets(faces or flat sides) the stone will have and what the angles of those faces are.
If your faceting machine has the capability you either mount the stone and let the machine cut all the facets or you mount the dop at the proper angle, set the depth, and grind each surface flat. Like tumbling you will have to use successively finer grits then polish.
I'm sure a real faceter will tell me where my guesses are bogus. Let the real experts speak.
csroc
|
|
|
|
Post by Alice on Mar 17, 2005 13:20:09 GMT -5
tweetie
in some cases (like emeralds) they use oil to polish the stones and it also hides all the fractures. The oil is shiney which makes the stone look like glass.
If you ever buy an emerald ring, don't be surprised if the jewler warns you about washing your hands / dishes with it on your finger. In time the emerald would start to dull, and fractures would become visible.
|
|
|
|
Post by Tweetiepy on Mar 17, 2005 13:51:05 GMT -5
I guess my real question would be - how do they get the inside of the stone to look like glass? - is it that the outside hides the inside ugliness? - i mean the inside is not glass-like it is still a rock - I guess I don't really need to know how to facet as such, but more like how do they hide the inside?
|
|
|
|
Post by Alice on Mar 17, 2005 14:03:25 GMT -5
The glass ones that you see, actually look like glass in the rough. After getting all the matrix off you will discover some gems do appear see through, and some that aren't see through at all.
The ones that are see through are usually the ones that make it to be faceted.
|
|
|
|
Post by docone31 on Mar 17, 2005 18:02:43 GMT -5
I love reading this post so far. Good guess work, even with oiling stone.
Faceting is a precise science. There are meet point faceters, and preform faceters. Those two schools won't be discussed here.
The stone to be faceted, is an item. Within that item is a ratio of Critical Angle, Isometric Adjusted offset, ISO, and Plane Schematic.
The Critical Angle of a stone, depends on its type. Stones today have a listed Critical Angle.
A gemologist is a person who specializes in the study of gems.
A facet, is a plane cut into a gem/stone. In most cases, the facet becomes a mirror that reflects light out of the stone. In other words, the light would enter the table, and crown facets, the top of the stone above the girdle. It also enters from the culette.
The pavillion facets reflect light through the stone finalizing by exiting through the table, or crown facets in designed order.
Like tumbling, the gems/stones are cut, and polished in descending order. The difference is, the facet is cut to precise proportions with the final polish ending at the coordinate.
Oiling, and treatments, seal the stone to be faceted. They add transparency by closing the fractures, pores, grains so the final stone looks flawless. Most treatments today are accepted as a flawless product. Diamonds are treated, emeralds, rubies, saphires, amythist, topaz, all beryls, tanzanite, iolites, quartz, alexandrites. It is actually rare to find an untreated stone in today's market.
A faceter designs, uses an existing design, to enhance colour, design, fire, and total appearance. A faceter also cuts a stone to utilize the most grain/ct weight, and fit a particular setting.
The polish process grinds the final scratches left by the Final Lap. That is the last lap used to cut the stone. I use a phenolic lap with Cerium Oxide to polish my stones.
Cutting a cabachon displays the outside of the stone. A few of us I would consider masters at this. Faceting displays the inside, and the light collection and specific properties of a particular stone which is cut to fit a setting maximising faceting qualities.
So, tumbling, cabbing, shows the outside, and if we are lucky shows the inside also. Faceting bends light inside the stone.
No particular school is better than the other. Each application has its purpose. Some designs I do are around a cab. Some are around a design that uses the properties of a stone to complete. Each has its purpose.
Tumbling can be more frustrating than faceting. Faceting a stone can take as long as tumbling. The emerald I did took 18wks to complete.
We should all be proud.
|
|
rollingstone
starting to spend too much on rocks
Member since July 2009
Posts: 236
|
Post by rollingstone on Mar 17, 2005 18:32:19 GMT -5
I guess my real question would be - how do they get the inside of the stone to look like glass? - is it that the outside hides the inside ugliness? - i mean the inside is not glass-like it is still a rock - I guess I don't really need to know how to facet as such, but more like how do they hide the inside? For gem quality stones, the kind that are faceted, the stone is transparent like coloured glass to begin with, there is no internal ugliness. As Doc says, the facets form little mirrors for the light to bounce around inside the stone and then emerge in a planned pattern or "fire". The kinds of emerald that people are picking up cheap on ebay for tumbling are not the kind of quality that will produce gem-quality faceted emeralds -- those are very rare and very expensive. Well, they may get lucky and find a few that are facetable, but most will just be tumbling quality only. |
|
rollingstone
starting to spend too much on rocks
Member since July 2009
Posts: 236
|
Post by rollingstone on Mar 17, 2005 18:46:30 GMT -5
Here's a link to somewhere that sells facet quality rough.... scroll down to find the emerald pics. Note that these folks are selling facet quality rough emerald for $30 to $75 per carat. (A carat is 0.2 grams... so there are about 142 carats in one ounce, so an ounce of facet quality emerald pieces would cost roughly $7,000 here.) This is very different than the stuff people are tumbling. www.facetingrough.com/rough_c-k.shtml |
|
|
|
Post by docone31 on Mar 17, 2005 18:49:58 GMT -5
With all due respect, I have found a very high quantity of facetable material from the mine run gems. Most people I make jewelery for, like the faceted mine run better than the "gem" grade emeralds. They like the rich colour. Most of the mine run emeralds have internal stress fractures and look like hot spots when faceted up. They set as well as any emerald, and the deep green ends up being a real enhancement. People are only buying the light green, and transparent green as it is all that is currently available.
I have faceted the "priceless" transparent green emeralds, and, put a mine run and a "priceless" one together and I would sell the mine run before I sell the others.
My best seller is a blend of clear/grey/deep green batch. When I facet the stone, I blend the design to the colour blending. I am doing one now, that is a spinning triangle. I am putting the lighter banding behind the spinning facets. I have high hopes.
That is what it is all about. I tell my students, if you like it, it will sell. I am the most critical judge I have ever met. Most folks do not see, even when studying, the defects I see from a distance.
I think the mine run stones make the best faceting of all.
|
|
|
|
Post by Tweetiepy on Mar 17, 2005 18:54:12 GMT -5
Doesn't Alice have a piece of clear emerald stuck to some bit of matrix? It's the one she was keeping an eye out for
|
|
rollingstone
starting to spend too much on rocks
Member since July 2009
Posts: 236
|
Post by rollingstone on Mar 17, 2005 18:57:15 GMT -5
Hey Doc, you're miles ahead of me on this subject, and I'm not surprised that you can work your magic with some lower quality stones. I just meant to point out that emeralds that as Tweetie said are "solid and non see through" are very different than the kind that are faceted. I take it that the mine run stones you use are still transparent, but just have some internal flaws you find a way to work around?
|
|
|
|
Post by docone31 on Mar 17, 2005 19:31:45 GMT -5
One of the reasons I do not like gem grade quality facet rough is the amount of waste. A facet has to deal with 60% of the stone that goes up in dust or in the waste tank. A 100ct piece of facet rough MIGHT end up with 35cts finished! That is if there is no unseen fracture.
Top Alexandrite rough is 6500$ a carat. Mine run rough is per pound.
Faceting is no special art, or arcane skill. It is keeping the machine clean, aligned, listening to the cut, and just getting used to the whole process. It is filtering the drip water, even household tap water has grit, measuring the planes and distances. Designs are availabel and there is Gemcad for those who want to design. Stones have known critical angle, ISO, and moment.
To be honest, at my shop, Once I set my first cut, the other matching cuts I just plop down on the stone, the machine does the rest. I will set the stone, get up, wait on a customer, walk around. Polishing is different. Each facet needs direct attention. I have been seen repairing jewelery, faceting, and designing at the same time.
It is like anything else. My first facet cut, I sweated small children. The stone came out miserably. Once I did it once, it got better. I learned a 3000$ lesson. I chewed up my laps second time out. I had to get my machine re-aligned. Today I do some from memory.
With the machines available today, even I can make some great pieces. It is just learning how, and I will help anyone who wants to learn.
I have faceted Lapis. What a beautiful stone faceted!
Every thing we do is easy once we know how. Believe me, if I can do it, so can anyone!
I also sharpen my gravers on my facting machine. Bad boy but what a precise point it makes. That turns a tool into a precise instrument! A graver sharpened on a faceting machine cuts gold and silver like a razor blade on wax.
I have done faceting with a tinker toy round joint. It worked pretty well but it was not as precise as a floating tool rest, index, and protractor.
If you can see it, you can make it.
|
|
stefan
Cave Dweller
Member since January 2005
Posts: 14,113
|
Post by stefan on Mar 18, 2005 11:24:12 GMT -5
Cool thread! Doc I am gonna visit you someday! I have never been to rattown so I figure I should make the trip! Anyway- Tweet- Do a web search on Herkimer Diamonds- Are These more of what you are thinking about? Just remember there are variuos Grades of material- Tumbling rough- is Low grade material- cabbing rough- a bit better- faceting rough still better- Gem quality- probably the highest grade! If I get a chance this weekend I will take some pixs of various grades of Herkimer Diamonds.
|
|
|
|
Post by docone31 on Mar 18, 2005 19:36:41 GMT -5
Stefan, you will like Port Richey. It is one of the few undiscovered places in Floriduh left. House prices are still reasonable, and doubling every moment. Jobs are everywhere, and being a suburb of Tampa, there is a lot going on.
On the flip side, Punta Gorda was listed in Money magazine as the best place to live in the US., and we found it to be a snake pit. It was miserable. Over inflated houses, everybody was paranoid, nobody finished the job on anything, and people really drove like nitwits, everywhere, Ft. Myers, Port Charlotte, Punta Gorda, Venice, it really sucked.
No body knows Port Richey is here! Tourist season means a few more cars on the road than usual. Big deal.
You would love it here. Centrally located between Tampa, Orlando, Lake City, Silver Springs.
|
|
