Q. for Michael E and other optics experts

[raddygast]

Apologies for this post; it may be both too technical to be interesting to most people, and too vague to be comprehensible to the technical people. But I really need some help because I have to contact my jewellery designer ASAP if I want to switch from a semi-bezel to a full-bezel.

Ok, I am now beginning to seriously wonder what the best setting would be for my red spinel.
(pictures here)

Here is the situation. It is very well cut, in a modified emerald step cut. Well proportioned as well. 7.61 x 6.21 x 4.79mm. Very good brilliance for this cut: 65% brilliance, 35% extinction, 0% windowing.

Here''s the problem. I have been observing it in different lights for a week now. Most of my observing is done by tilting the stone to the optimum angle for color flashes and light return. All of my pictures were also taken with this method. But I have noticed (especially when there is a lot of ambient daylight inside my apartment) that sometimes/often the color of the stone appears to bleed at many viewing angles.

At first I couldn''t tell if it was officially windowing, since I don''t fully understand the term yet. I know that a window is due to poor cutting (and low R.I. makes this worse), and is where you can see through a gem to the other side. In a sense this means that the light from near your eyes goes all the way through and doesn''t reflect back (so in theory it should be extinct). But on the other hand, light from the other side comes right back through the window to your eyes (so it should be half as saturated, roughly, as the "good" light which comes through the table, bounces off facets, and returns to your eye).

Now I don''t understand it fully because I don''t grasp how one can read, for example, text printed on a page, through a window. If the light bleeds through the gem, hits the text, and reflects (from the paper) back through the gem, should it not in that case appear fairly saturated since it travelled twice through the depth of the gem? Perhaps the saturation is the result of constant bouncing back and forth at precise angles before it comes back to the eye.

Anyway, to get back to the point. My stone is officially not "windowed" (0% windowing according to Richard). However, I am sure this is a measurement taken at the optimal angle perpendicular to the table. As Michael_E was describing, when you tilt the stone even a moderate amount, the window is instantly visible. It is largest through the large chunky sides of the stone (the big triangular looking sections along the length dimension). There is a miniature version of this along the "width" side too, but the length side is more severe. To me this seems like either light leakage or the reverse -- light entry from the sides of the stone, not the crown facets, that ends up coming to my eye. It is very unsaturated pink, which is what I would expect viewing light for example through the pavilion facets (as expected).

Now, in this state the gem appears quite dead -- not brilliant, and of a very dull, transparent lifeless color. But I have noticed that in this situation, which usually arises depending on how much diffuse light there is and where the light is coming from, if I cup my hands around the side of the stone (which is in a little plastic case and held with the table perpendicular to the ground, i.e. not tilted) then the stone suddenly appears quite beautiful again and the "dead facets" shine to life. Almost like the gem is generating its own light.

I think what is happening is that I minimize light entering through the side windows, so that the only light I see is the ambient light that has properly entered through the table and crown facets, and then reflected properly back to my eye. If I leave my eyes and the stone in the same position, and remove my hands, suddenly the stone goes "dead" again.

So my question is -- I am considering setting the stone in nice semi-bezel, where the bezel would cover most of the north and south ends of the stone, and just a tiny bit of the length dimension. Since the length "windows" are much larger than the width ones, maybe this is a bad idea? Maybe the bezels should cover the length dimension and leave the width one open?

And maybe, just maybe, it''s a dumb idea to have a semi-bezel at all, and the full bezel is the only way to go? Is there any way to know? Does my description make any sense to anyone? I hope I can get some advice on this. I initially wanted a semi-bezel to show off more of the stone, and its beautifully cut parameters and dimensions. Now I am worried that maybe the stone will look lifeless the more it is exposed on its sides, and the best setting would be a nice full bezel (thin, and only slightly reaching above the girdle, so that part of the crown facets and the table would be elevated above the bezel walls'' level).

Any help?

 

[Michael_E]

raddygast,
Emerald cuts are the toughest cut to show what you refer to as "life" from a wide range of angles. Scintillation, or the multitude of sparking lights that are displayed by many gems, are actually minimized by the arrangement of facets and their angles on almost all step cut stones. As you have noticed, in more diffuse lighting situations, you will see more life in your stone, by covering the sides of the stone and allowing the low levels of reflected light to be more easily seen as it is reflected off of the sides of the stone and is not overwhelmed by any light being transmitted through the stone. Usually the lighter hue of light that is reflected off of the side facets is more than enough to offset the darker body color of these deeper colored stones like spinel, sapphire and garnet. Part of it depends on the color and brightness of the background that you are holding the stone against and the fact that even though you are moving the stone, you are still looking through a window which does not show any change in color as you move it slightly, hence you see good color, but no "life". This life comes from the rapid changes in light level as you see different light sources reflecting from the pavilion facets at angles that may have interference from stronger light coming through the "window". The life is like a light being flicked on and off, whereas the window color never changes.
Your comment about light going through the stone, hitting a printed page and then bouncing back through the stone, kind of had me smiling. The light actually does not go through the stone initially. It is ambient light that hits the text and then shines through the window to your eyes. Try sitting the stone table up on a white business card with a bit of clay, beeswax or something sticky on the culet, that leaves most of the pavilion free. If you shine a penlight onto the stone, in a dark room, until it falls on text that you can read in a lighted room, you will see that the angle of the light going through the stone is at the same angle as your eye would be and that there is not enough reflected back through the stone to make it possible to read the text.
Those numbers that you sighted for brilliance, extinction and windowing are ONLY judged in diffuse light when the stone is viewed perpendicular to the table. The idea of windowing in judging a stones cut is only valid when viewed this way. All other windowing, such as when a stone is tilted are more a function of the stones R.I. and not of it''s cut. These numbers don''t mean much when you start moving the stone around anyway, because those zones of extinction and windowing can be reversed when the stone is moved and those zones become reflective and bright. Those numbers are more designed to tell you if a stone has been cut too shallowly, which your is not. Nothing compares to just plain looking at the stone. We don''t spend time dealing with these things so that we can compare numbers and statistics. We hold these things in our life for a while because they are beautiful and perhaps have some meaning. If they are durable and rare, well so much the better. Because of this focus on beauty, which you obviously hold, you need to decide which method of setting the stone looks better to you. I personally like to look at a stone from many different angles, not just from the top dead center. I like to move it around and watch how the light changes as it moves through it. Pick the stone up with tweezers and look directly through the side. Is it beautiful ? There''s very little "life" at this angle, but the stone is still very attractive, I''ll bet. There is no right way, wrong way or even a perfect way to set your stone. If you like to have the sides open, then I say do it. You can always shade the stone with your hand if you want to see the "hidden" life that it possesses.
Just as a side note here. I think that your spinel is as beautiful as any ruby. The clarity is fantastic and although I''m sure that the screen color is not right on, the color is undoubtedly tremendous too. Too often we get caught up in the names and numbers of what we''ve got and what it''s worth and forget about the pure intrinsic beauty of the piece itself. You''ve got a great one there, so enjoy it for a long time !

 

[valeria101]

You have spent quite a bit of effort finding the spinel... no wonder you want whatever setting to keep the stone on permanent display and nothing more. That can be done too. On the other side, the terrific red piece may well become the main attraction of a ring that''s quite impressive on it''s own. A gem collector may never set and wear his prizes, but this one gem is supposed to be worn as one component of a ring. Whatever style will look better with a better stone, no matter what

 

[strmrdr]

Michael disagreed with me in another thread or maybe im just not explaining it right but some stones look better in an enclosed setting where it is dark behind them.
My theory is that you get a mirror effect which returns some light.
I know the window in an oval garnet I have is 1/2 to 1/3 the size with a dark area behind it for the same amount of tilt and it takes more tilt for it to become visible.
When I have it mounted im thinking of having the inside of the bezel enameled black or red.
Maybe its just the lack of contrast in the background behing it that hides it instead of a mirror effect but it does seem to look brighter.
dunno.
Not sure if my reasoning behind it is currect but I do know what I see.

Maybe Michael has a better explaination of why it does that.

 

[raddygast]

Thanks guys, for the replies.

Michael, I''m pretty sure I understand what you''re saying now. You personally prefer to be able to see more of the gem. Yes, when I view it from the side, I do see a big window, and the window color (i.e. not "life", but more consistent) is pretty. But personally, I find it too subdued for my tastes -- like when you view a stone from the pavilion as opposed to the table. Initially I thought a semi-bezel would make the stone seem bigger and show off its proprtions and cutting more nicely. But now I see that the more open the stone, the more the compromise between "showing" more of the stone''s shape, and allowing the true and proper light (that enters through the table/crown) to be overwhelmed by light that leaks in from other areas.

Now, truth be told, I actually think that a full bezel might offer me pretty much everything that I want. I have made a little bezel setting for the stone (out of aluminum foil), based on curiosity and strmrdr''s comments. Now I actually think I want a full bezel that is polished to a high shine so that it almost acts like a mirror, i.e. it doesn''t fully allow light to escape through a window; it bounces some of it around. But more importantly it doesn''t allow light to leak in through the sides in harsh lighting.

What I''ve discovered is that the bezel actually makes the stone seem redder. Either it is deepening the color in conditions where it''s liable to look pinkish or darkish mauve, or something else, I don''t know. But, to my eye, it definitely looks beautiful.

The full bezel almost makes the gem look more mysterious and flirtatious. Only a tiny bit sticks out beyond the bezel, but it''s the most beautiful bit -- basically the crown facets (since mine is an emerald step-cut, it seems, it has two sets of facets -- one directly above the girdle proper, quite thin, then another thin one above the first crown facet, then finally it turns into the table). I love the look.

Incidentally, it seems like the bezel actually makes the stone look bigger, not smaller as I had previously assumed. It gives it this wonderful definition and accentuates its squareness. And keep in mind this is just a horrible makeshift job I did with aluminum foil -- I can''t imagine how beautiful it would look with a well-crafted but extremely thin, precise, and feminine bezel made of 95 plat/5 ruthenium.

Does this make any sense? As you say I suppose it''s personal preference. My jeweller is making sketches of a couple half-bezels, but a full-bezel thrown in there too, so I should be able to compare. Of course, once the wax is made, it won''t be reflective nor the color of white metal so it won''t really capture the final look, and I think it''s a good thing that I played around with the aluminum foil today.

P.S. I hope to god the aluminum foil isn''t going to scratch my stone. Since its hardness is 8, I think it''s fairly durable, but I''m not sure. Aluminum foil is paper-thin, but I wonder when it gets crumpled and has little sharp peaks and valleys, if I press too hard against the stone or drag it, could it possibly scratch it? Probably not -- I''m just being paranoid. I think.

 

[raddygast]

ridiculous "bezel" pics

 

[Michael_E]

raddygast,
That is one fine Alu-bezel you''ve got there. A little super glue and you won''t need anyone to make a setting for this.

I think that anything you do with this will look good. Make sure to post the finished pictures !

 

[canuk-gal]

HI:

On the topic of bezels/optics--I went today to see the wax of the ring I want to set my tourmaline into. To make a long story short, I did NOT like the half bezel at all! She did find some lovely cushion shaped peridots to go with it, but I just couldn''t groove on what I saw.

Now I am back to a full bezel route. Will that be my final answer--I hope so!!

cheers--Sharon

 

[raddygast]

Michael E: Thank you. I really should look into an alternative career in kitchen-supply jewellery.

canuk-gal: I wonder. If you veto certain designs, does that cost you extra? I mean it takes the designer more time to do alternate sketches. What''s more, if you go all the way to the wax stage then realize you don''t like it, that''s an even bigger setback isn''t it? I know the wax is for precisely that -- getting a feel for what something looks like, 3D, tangibly. But I''m worried that my custom design costs will skyrocket after I veto my 42nd wax!

Anyway, what was it about the half-bezel you didn''t like? I think I''m leaning full bezel rather heavily now too.

 

[canuk-gal]

Date: 1/28/2005 5

2:51 PM
Author: raddygast
Michael E: Thank you. I really should look into an alternative career in kitchen-supply jewellery.

canuk-gal: I wonder. If you veto certain designs, does that cost you extra? I mean it takes the designer more time to do alternate sketches. What''s more, if you go all the way to the wax stage then realize you don''t like it, that''s an even bigger setback isn''t it? I know the wax is for precisely that -- getting a feel for what something looks like, 3D, tangibly. But I''m worried that my custom design costs will skyrocket after I veto my 42nd wax!

Anyway, what was it about the half-bezel you didn''t like? I think I''m leaning full bezel rather heavily now too.

HI:

Before we even got to the wax design stage--I fully disclosed to the designer that I was unsure about the 1/2 bezel setting, hence I wanted to know if she was interested in completing the wax as I didn''t want to waste her time should it need changing. She assured me that is was AOK should I change my mind, and at no time was I told there would be incremental costs involved for two waxes. Not that that would be a problem, but she has not mentioned anything to date..and I "know" this girl as she just made me some fab briolette garnet earrings; so our communication is fairly clear.

I don''t know how to articulate my uneasness with the design--it seemed unfinished some how. Does that make sense? Absolutely no WOW factor, none of that "I have to have it" feeling. Granted waxes are not hugely appealling but I couldn''t talk myself into believing even when finished it would be great. Thing is I have tried on many full bezels stone rings and liked them, whereas I only had a photo of the style of ring the wax was based on, and it wasn''t afterall what I expected. But isn''t that what "custom" work is all about?

cheers--Sharon

 

[Michael_E]

I don''t know how to articulate my uneasness with the design--it seemed unfinished some how. Does that make sense? Absolutely no WOW factor, none of that ''I have to have it'' feeling. Granted waxes are not hugely appealling but I couldn''t talk myself into believing even when finished it would be great. Thing is I have tried on many full bezels stone rings and liked them, whereas I only had a photo of the style of ring the wax was based on, and it wasn''t afterall what I expected. But isn''t that what ''custom'' work is all about?

cheers--Sharon

Well, from my perspective as a jeweler I would have to say that custom work done for a particular client should not be done as a hit or miss thing. It has to be something that you as the client will absolutely love when it''s done, or I haven''t done my job. Even if you can''t articulate exactly what you are looking for, it is still on my shoulders to make the direction that a piece is evolving into, understandable to you as the client and then take direction from you to make it "just right".
Once I have your general style requirements I can then make up sketches and get very close to what you want before ever starting on the wax. With the new technologies in CAD, 3D rendering and computer controlled model making, there is no reason for you not to know exactly what you will be getting before it is ever committed to wax. Many traditional jewelers still balk at the use of these tools because they feel that it takes away their creativity somehow. The reality is that it can make a client perfectly satisfied with a design with much less effort than what it would take to make numerous waxes. Some clients who are ultra picky and could easily drive you nuts before, can now be given a complete virtual "tour" of their ring, make any changes that they might want, as often as they want, and be very satisfied with the end result since there can''t be any surprises. Even if your jeweler doesn''t use these tools, many aspects of this design technology are available to the end user right now from different Internet vendors. There''s absolutely no reason not to have a clear idea of what your custom piece will look like.

 

[canuk-gal]

HI:

I appreciate your candor Micheal. Fact is, no one is more "guilty" than I for not liking the wax for I must own to having been mistaken in my enthusiasn for the original design--it was just too "open" afterall; a perspective I could not acertain from the printed picture and subsequent drawing of the same. I know the creation of the wax is time consuming, and perhaps had comptuter software been used there would have been less margin for "error". That said, I do want to give the designer credit for being very talented and successful--I have bought many "drop dead gorgeous" pieces from them that I just "had to have". Unfortunately this first attempt was not one of them....but luckily it can be rectified.

I find this forum very useful....as I buy and ponder buying more and more colored stones.......

cheers--Sharon