Thursday, January 6, 2011

Lapidary Degrees of Fineness

Working in stone was a different sort of attraction to me than metal.
Initially and Continuously.
I first approached stone way before jewelry. Just the awe it would inspire. The way things mineraly were formed and their stunning beauty and variety.
After being into jewelry quite awhile and purchasing gems at an ever increasing disappointment level as my metal work surpassed the quality levels I could find in obtainable stones,  I knew I needed to approach mineral gems from a different perspective.
I couldnt get what I wanted because the cutters were making such a mess out of perfectly good materials.
Or they were doing fair work on stones they used little or no creative vision to layout. Designs obviously put together to achieve the most pieces from a slab.
The dreaded "cookie cutter" approach.
I knew I needed to get into making my own precious stone cabochons if I was going to achieve what I wanted out of my metalwork.
Achieving fineness in stonework is a lot more oriented to rudiments of technique and repetition than metalwork. Dues need to be paid in terms of much time spent in getting it right. That's ok though.  Much harder to overwork a stone than a piece of jewelry.
They have a wider latitude of being reworked again and again till its right.
A lot of what I see in handcut lapidary is sorely lacking in enough time spent.
Thats probably the biggest single cause of poor stonework.
And those specifics arent as variable, as you are essentially creating by releasing, not fabrication.
Its removal not,  construction.
You arent the master, The stone already is. Its up to you to gently bring its inner potential to light.
You arent really creating anything.
But its also true that you hold the keys to a focal stone that will be an exemplary definition of the mineral species, or a chossy, pitted, undercut, uneven, half sculpted, poorly polished, hack job.
Its up to you.
A stone needs a decent and even surface, and symmetry of radius to have visual continuity.
Look at it often as you sand. Even it out. If its a freeform - fine, it can have a lot of latitude, but if its a specific shape, use a template.
But either way the surface must blend smoothly.
Long tube fluorescents overhead are nice as they reflect two long parallel lines you can judge curvature evenness with. Moving around should show smooth transition over the whole visible face.  And the back should be like a mirror to that light, the tubes should reflect two parallel lnes all across it. A stone with an unfinished back is an unfinished stone. It removes the option to the jeweler of setting that stone in an open backed or even a double sided setting. Finish the backs.
Undercutting is a very common fault and is difficult if not impossible to completely eliminate in every stone.
It comes from having variable hardness materials or zones side by side, the sanding wheels will obviously wear away the softer material first. The greater the contrast in hardness the more pronounced and difficult it is to remove. A light touch, the use of flat laps, and concave hardwood wheels and diamond paste is all in the bag of tricks against this "firescale of the lapidary world."
All this takes time. And many lapidaries, knowing they are selling a supply try and kick it out fast.
I remember one fellow whose first day on a popular handmade sight came into the thread with a bold
"Howdy, how long does it take you guys to cut a stone? because I have it down to ten minutes per cab."
His stuff is far from what his moniker claims it to be.
Its not a race.
True enough you can get good at repetition, but each stone is unique as well. It takes some stones a long time to be sculpted well, and given the proper attention. Several hours or more on a complex stone is not uncommon .
And a small but even solder bevel should be sanded on the bottom edge of all cabochons that are to be bezel set. This provides relief for the little solder fillet that is inside the bezel, without this you subject the stone to unven presures on the edge when setting, possibly leading to fractures.
The only time this can be overlooked is if the cabochon is to be prong set. Typically reserved for colored clear stones. It allows them to be st flat on the seat with no unsightly gap.
In a sideview the stones profile, which is generally a parabola of some shape,  sometimes with an edge sometimes smooth, can follow any number of configurations but one.
And that one is straight sided.
I am sure there are a lot of fine Lapidaries out there that would challenge this.
So be it.
Most of them are not metalsmiths that have done complex bezel settings.
Setting a straight sided stone has distinct disadvantages and the only advantage is to the cutter on speeding up the process by not having to be as accurate in creating a smooth bezel bevel.
When the stones side is straight, it forces the bezel to be vertical, with no ability to hold. Thus the bezel must be folded over a sharp lip, with attendant difficulties at the corners with buckling and wrinkles. That stone is held in by the downward pressure of the bezel after folding, NOT by a cinching due to a taper which is MUCH less prone to loosening. And the straight sided bezels are limited to thin bezel gauges to be effectively set.
The other thing straight sides do is to void the abilities of optional setting techniques. Such as using thick walled bezels that are hammer set below the edge, or down low on the radius if no edge is on the stone. Or thick bezels that are flush edged with the dome edge of the stone to leave a clean face and very smart clean visual.  Or such things as partial bezels which require a taper to have any grip at all on the stone. And prong settings where the prong is snug to the sides of the stone but not folded over the top to keep the face of the stone clean. None of these types of setting are possible with a straight sided stone. Thus to cut one eliminates all the options a jeweler has to utilize the stone in their designs except the fold over. This is going to limit its sale potential. And lower its value.
Which brings us to finish. POLISH THE STONE. Bring it up to the highest gloss that the material will allow. And then some. I wont go into specifics on techniques as they are enough to fill a book by themselves, but basically use a 10x loupe and check the stone over. if you see scratches, its time to go back and rework it.
Lastly is layout. It is one of the areas where real creativity beyond the limited effects of good sculpting are evident. Get a good fine drafting pencil and sketch a bunch of different potentials before finally settling in on a final design. Slabs have a nice soft roughness that accepts pencil nicely.
Forget about how many you can get out of a slab.
Thats not the point. And make the shape work with the design.  Look at what you are doing, look at what the stone has to offer. If it doesnt seem right, lay it aside and come back to it later. No hurries, No worries.
Take a tour of sites and shops and get a critical eye to the way folks cut. It wont be long till you can start to see why an 8.00 cab is an 8.00 cab
Good enough is not good.  Good enough may be ok for you.  You may even be able to sell a lot of good enough cabochons. But as those jewelers that buy such stones get better, they will graduate to better lapidary.  Good enough isnt stiving for excellence. Good Enough is not a Degree of Fineness

1 comment:

  1. Thanks for sharing your wisdom. I am slowly learning about what to look for in quality stones. Now I know a little more. Your stones are amazing. I hope to be able to obtain more of them in the future.