Lapidaryforum.net
Rock Art => Cabochons, Intarsias, Cameos => Topic started by: finegemdesigns on January 02, 2018, 11:57:34 AM
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I have included an image of both stones but a a second look is in the video to see reflections.
The material is lavender jadeite from Guatemala.
(http://www.zbestvalue.com/images26/2jadespolish3.jpg)
https://www.youtube.com/watch?v=OD6U9rwn_wo
I used 2 common finishing techniques to polish these stones.
The 2 techniques applied will be revealed at the end of the poll.
Please also cast your vote and opinions in the comments section here and at youtube.
:idea1:
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Teardrop on left is better. The surface is less pitted and grainy
Bob
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They look the same to me. :dontknow:
On the video the right kite looks more shiny, but I think it's from the shape and the way the light is hitting it. (My eyesight sucks!)
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Teardrop surface is smoother - but that could be difference in rough.
Light reflection is sharper in kite shape. Edge of light is more defined. If dome profile is same on both I vote for the kite.
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The one on the left is better. Send me the kite and I will try "scuff" polishing on it and then you can compare that to what you did.....
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I'm going to give a few more pieces of information.
One of these cabs was polished with all diamond to 1200 then Poly-Al-F (Aluminum Oxide) polish on leather.
The other was polished with all diamond to 1200 then 14,000-50,000-100,000.
Shaping and rough grind was the same on both with coarser grit diamond.
The back flat surfaces were used since they work better for reflections. But as we all know curved surfaces are easier to polish and gain a more reflective surface. But curved doesn't work as well in a test like this.
Both cabochons were cut from the same piece of rough jadeite.
Note to bobby1: There is no pitting on either of these cabochons lol.
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Hmmm. I thought this poll would generate more comments than it has. Over eighty views, but only nine votes. A bit of a surprise to me. Seemed like an interesting bit of fun.
Now - being from the "immediate gratification" generation - I just want to know the bloody answer... .
Finegemdesigns - that last bit was said in jest. Well, mostly, anyway. My Zen must be broken.
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4 more days. Want to get as many votes as possible.
:icon_study: :icon_study: :read: :icon_bounce: :happy3: :glasses2:
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If the 2 shapes were the same, then this world be a more equal judgement. The type of shape can give a different visual effect.
Karen
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The shape comment is good. Finegemdesigns' statement that the flat backs are shown helped me a little.
When first viewing it I had assumed we were seeing the face sides with some degree of low dome.
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The kite is closer so the flash shows more, but I'm not sure it is really better, or if my eyes are deceiving me. I think this is the kind of test that is easily resolved in person, but much harder to tell via video or picture. Perhaps if both were the same shape and the camera were focused between them so that the light source was equally distributed, I would know if the kite is actually better or not.
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The video does show the light (it's a fixed lamp) reflection moving across both of them. I still didn't pick up that we were seeing the flat backs even in the video.
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The kite is closer so the flash shows more, but I'm not sure it is really better, or if my eyes are deceiving me. I think this is the kind of test that is easily resolved in person, but much harder to tell via video or picture. Perhaps if both were the same shape and the camera were focused between them so that the light source was equally distributed, I would know if the kite is actually better or not.
Just a note: Both cabochons are the same distance from the camera. Also the light that is reflecting is to the LEFT so technically speaking the tear drop is closer to the light. Not much but it is.
I'm thinking I might do another test after this with something more uniform like clear quartz. This would allow viewers to see the shape of the light better to see which edges are sharper in the reflections. The internal chatoyance of the jadeite seems to create some slight blurriness in the reflections.
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i watched the video a couple times staring at the shine. they both look fairly even to me.
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The idea of using clear quartz wouldn’t completely resolve the question in my opinion, because some techniques work better for one material and other techniques work better for another. However, using as close as possible to identical pieces of the same material would resolve which technique to use for that particular material.
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Left Tear Drop was polished with 14,000-50,000-100,000 diamond.
Right Kite was polished with Linde A sapphire powder.
Thanks to everyone who participated.
Which has better polish?
Voting here:
Left Tear Drop = 3
Right Kite = 5
Same = 3
youtube votes - Right Kite is better = 1
Totals:
Left Tear Drop = 3
Right Kite = 6
Same = 3
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One more question about the polishing methods.
What type of lap (or wheel) was used for the diamond on the teardrop?
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One more question about the polishing methods.
What type of lap (or wheel) was used for the diamond on the teardrop?
It's a canvas pad like the one shown here:
https://www.kingsleynorth.com/skshop/product.php?id=96664&catID=1055
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Material used looks to have a un-stabilized surface, meaning hard an soft formation zones in material causing a under cutting of material during cabbing.
soft backing on pad well cause polish to carve deep concave dishing on the surface.
Wood polish wheels ( Maple clear grain ) are best for leveling the dome, Then the felt or wool pad - with your call of polish.
Jack
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Jack, do you know of anyone who sells maple wheels? I used to have a couple but they were taken in a burglary. I'd have some made but don't know anyone who does that kind of woodwork locally.
TIA, Rick
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Material used looks to have a un-stabilized surface, meaning hard an soft formation zones in material causing a under cutting of material during cabbing.
soft backing on pad well cause polish to carve deep concave dishing on the surface.
Wood polish wheels ( Maple clear grain ) are best for leveling the dome, Then the felt or wool pad - with your call of polish.
Jack
I appreciate your input but I'm not convinced that the theories involving undercutting and orange-peel are accurate. For example I have read pages where people believe that you can stop undercutting by use of different techniques and polishing. IMO there are physical characteristics that make this virtually impossible in some rocks like chrysocolla in quartz. You have softer 4-5 MOHs particles of chrysocolla floating in hard 7 MOHs gate. By definition a surface imbedded with abrasives will cut the agate slower than the chrysocolla thus creating lower surface areas on a polished surface. But is this really a problem? Really? I can cut and polish chrysocolla in quartz easily and it looks fine top down when viewed.
(https://www.finegemdesigns.com/images6b/nov17-CIQ.jpg)
Also nobody seems to have a problem with other gems like jaspers and turquoise that contain minerals of different MOHs that have minor surface undercutting. The only argument I can see is if you are cutting with a super hard polishing surface like phenolic and you are employing some kind of stop like in faceting. In this case it might be possible to keep undercutting to an absolute minimum. Again we are talking cabochons here not faceted diamonds or rubies.
As far as this experiment it is apparent that the lavender jadeite does have some slight inconsistency in MOHs and also some chatoyancy that makes it difficult to get a perfect mirrored polished surface reflection. Remember though that these are FLATS not curved surfaces. I have a handpiece of the same rough with curved surfaces that are more glassy which is expected. I can probably make a video of this later so people can compare.
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Jack, do you know of anyone who sells maple wheels? I used to have a couple but they were taken in a burglary. I'd have some made but don't know anyone who does that kind of woodwork locally.
TIA, Rick
Don't know where you are located but if it's anywhere near a large city, my suggestion would be to find either a wood workers supply or a lumber yard that sells a variety of hard woods. Ask them to direct you to the local wood turners club and then ask them who could make what you want. Here in the Tucson area the local wood turners society meets at Woodworkers Source every month so the contact would be easy.
Jerry
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Re under cutting, the sphere making process often seems to produce the best results on material prone to undercutting, presumably because the sphere cutting equipment produces a very even pressure across the whole stone, where as manually cut stones have uneven pressure applied to them allowing fibres, soft spots etc to under cut. CNC carved jade also seems to avoid undercutting, probably for the same reason.
David
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Jack, do you know of anyone who sells maple wheels? I used to have a couple but they were taken in a burglary. I'd have some made but don't know anyone who does that kind of woodwork locally.
TIA, Rick
Don't know where you are located but if it's anywhere near a large city, my suggestion would be to find either a wood workers supply or a lumber yard that sells a variety of hard woods. Ask them to direct you to the local wood turners club and then ask them who could make what you want. Here in the Tucson area the local wood turners society meets at Woodworkers Source every month so the contact would be easy.
Jerry
Thanks Jerry. I'll follow through on that. Hadn't thought of it.
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Here is a video showing more reflective surfaces of polished lavender jadeite.
https://www.youtube.com/watch?v=Tpx154Sa_Ps
:idea1: