What am I seeing in these gems?

[Odyssey44]

I saw this peridot which is listed as precision cut. I was wondering what that black area is, radiating from the center out, kind of like the two hands of a clock at 10 to 9 if the 12 mark is at the right side of the gem. Could this be a problem with the cut? Extinction? Something else?




Then with this bicolor tourmaline I think I see a window in the middle. Vendor says no windows. Am I seeing things?

 

[Autumn in New England]

With regard to the peridot, the gif is turning too quickly for my tired eyeballs to really be able to tell whether we're looking at normal extinction, a cutting defect, or something else. From the still, it doesn't look like a window, and I also don't think it's horrible extinction. Most every gem has a touch of it. But I'd need to see a better video. PSA: Even precision cut gems can window.

So these "bar" cut toumalines tend to have at least one long step facet in the pavilion that will not reflect when you turn the stone. You can call it a window, but it's almost impossible to avoid for some reason. I'd ask for another video in tweezers. A white background will minimize the effect.

 

[Odyssey44]

I cannot figure out how to post a video! I am gif-ing the videos because they won't post. I don't know how people do it. I'm going to try to search again to see how.

Oh, that is why I always think I see a window in these bicolor stones that all seem to be cut that way. I really don't like these cuts.

I am forgetting I have seen precision cuts with windows. I wonder why this happens.

Thanks a bunch!!

 

[Autumn in New England]

I cannot figure out how to post a video! I am gif-ing the videos because they won't post. I don't know how people do it. I'm going to try to search again to see how.

Oh, that is why I always think I see a window in these bicolor stones that all seem to be cut that way. I really don't like these cuts.

I am forgetting I have seen precision cuts with windows. I wonder why this happens.

Thanks a bunch!!

It's so frustrating, isn't it? I don't know why this site allows uploading photos but not videos (perhaps it requires too much RAM/memory?). So you have to use a video hosting site, like vimeo or YT. I've even seen some folks use their FB page. Then you can post a link or embed it here.

Yep, most bi-color tourms have that cut (as does mine). I'm not a big fan either, but I suppose it's meant to best show the color graduation.

Not all gem cutters are created equal, so while they may aim for correct proportions and angles, sometimes they miss the mark. Experience is king!

 

[Avondale]

I cannot figure out how to post a video!

One word - imgur.

 

[fredflintstone]

I saw this peridot which is listed as precision cut. I was wondering what that black area is, radiating from the center out, kind of like the two hands of a clock at 10 to 9 if the 12 mark is at the right side of the gem. Could this be a problem with the cut? Extinction? Something else?




Then with this bicolor tourmaline I think I see a window in the middle. Vendor says no windows. Am I seeing things?

The Peridot has a tiny bit of extinction. Nothing major. As already said, most stones have extinction to a more or less degree. Nice stone.

The Tourmaline is bar cut. These cuts I'm not fond of especially when they are shallow. Deeper cut ones are fine, but the shallow ones stay away from them as they just don't reflect well the color of the stone on all the long pavilion facets where the deeper cut ones at a steeper angle work much better.

The stone you show is hard to tell, it does not look overly shallow, but the white background really hinders the exact appearance. Ask for tweezer or finger videos.

 

[Odyssey44]

Ok, thanks Autumn and Avondale for helping me figure out videos. I needed to use an intermediary to get the videos off instagram, and then I could upload to imgur.
Here is the peridot:

https://imgur.com/KYlKKGC

https://imgur.com/fmL2MrO

https://imgur.com/oKnqzaR

It seems like those clock hands are always there, so not sure what to make of it.

 

[LilAlex]

I think a "bar cut" is something different. Tourmaline of course occurs in long, bar-shaped crystals, but I think of the pixel-cut when I think of bar cut. I guess technically it's the opposed bar cut. I have always wanted a big juicy red garnet cut like this:




For the peridot, I think it is almost precision cut and you are seeing the effect of asymmetry in those radial pavilion facets. Since the material is less precious, I'm accustomed to seeing finer peridot with better symmetry.

That tourmaline exhibits a lovely watermelon gradation but the shape (outline) weirds me out a little -- hard to explain. I would much prefer a step-cut tourmaline but I think this end treatment can minimize darkening at the poles (?).

 

[Odyssey44]

It is taking me forever to get the videos working since they are from Instagram. I think I may have finally cracked it. Publer to Imgur to Media. Sometimes video does not take, but usually will after a refresh. Here are hopefully 4 videos of the tourmaline:

https://imgur.com/a/XWV2Usf

 

[Odyssey44]

Here is a completely different bicolor tourmaline. It is a similar cut. Are all those black bars appearing on the end extinction?

https://imgur.com/a/V5Az4l6

 

[Odyssey44]

The Peridot has a tiny bit of extinction. Nothing major. As already said, most stones have extinction to a more or less degree. Nice stone.

The Tourmaline is bar cut. These cuts I'm not fond of especially when they are shallow. Deeper cut ones are fine, but the shallow ones stay away from them as they just don't reflect well the color of the stone on all the long pavilion facets where the deeper cut ones at a steeper angle work much better.

The stone you show is hard to tell, it does not look overly shallow, but the white background really hinders the exact appearance. Ask for tweezer or finger videos.

How can you tell shallow stones? Does knowing measurements help? Are we looking for depth to be a certain percentage of width?

I also wanted to follow up with you on the pink/red irradiation of so much Afghan tourmaline. Are you finding that true of green and pink bicolor tourmaline like this too, or does the green mean they are more likely to be natural?

 

[fredflintstone]

I think a "bar cut" is something different. Tourmaline of course occurs in long, bar-shaped crystals, but I think of the pixel-cut when I think of bar cut. I guess technically it's the opposed bar cut. I have always wanted a big juicy red garnet cut like this:




For the peridot, I think it is almost precision cut and you are seeing the effect of asymmetry in those radial pavilion facets. Since the material is less precious, I'm accustomed to seeing finer peridot with better symmetry.

That tourmaline exhibits a lovely watermelon gradation but the shape (outline) weirds me out a little -- hard to explain. I would much prefer a step-cut tourmaline but I think this end treatment can minimize darkening at the poles (?).

Here is some info:

“The opposed bar cut is a faceting design that is popular for its unique appearance and versatility. It is often used in materials like tourmaline and can be applied to various gemstones, although it is less common in natural sapphires, rubies, spinels, or emeralds. This cut is characterized by its ability to showcase color and contrast, especially in darker materials, and is known for its aesthetic appeal and ease of cutting.”



“A bar cut gemstone refers to a type of gemstone cut characterized by its unique design, which allows for maximum light reflection and brilliance.

• The Barion cut is a popular design that features moon-shaped facets at the girdle, enhancing the gem's sparkle.

This cut is named after Basil Watermeyer, who invented it in 1971, and it is particularly effective for colored gemstones, allowing for longer length to width ratios and deeper designs.

Barion cuts are preferred for their ability to maximize brilliance and are often used in engagement rings, beads, and other jewelry pieces.

Overall, bar cut gemstones are known for their stunning visual appeal and ability to enhance the natural beauty of the gemstone.”

 

[LilAlex]

Thanks, @fredflintstone. Odd that AI does not say what an opposed bar cut actually is -- picture vs. a million words, I guess. I don't think it's just a step cut with an elongated LxW ratio.

I love an opposed bar cut but the reflecting-pixel effect is only prominent (I think) in larger stones and the only larger stones I can afford are too soft for this very "exposed" design! Must be a lot of waste, too, since I have never seen a corundum opposed-bar cut.

 

[Autumn in New England]

For me personally, I LOVE that peridot and the cut looks great to me (despite the clock hands, which I bet will move depending on how the gem is turned). But you're fussier than me, so perhaps there's a better fit out there.

Both of those tourmalines have fantastic cuts, IMO! Don't confuse extinction (cutting defect) with obstruction (external interference). I think we're seeing just a bit of obstruction in these tourms because that one end is pointed away from the camera. Beautiful eye candy indeed!

 

[Odyssey44]

For me personally, I LOVE that peridot and the cut looks great to me (despite the clock hands, which I bet will move depending on how the gem is turned). But you're fussier than me, so perhaps there's a better fit out there.

Both of those tourmalines have fantastic cuts, IMO! Don't confuse extinction (cutting defect) with obstruction (external interference). I think we're seeing just a bit of obstruction in these tourms because that one end is pointed away from the camera. Beautiful eye candy indeed!

Thanks so much!! I do like the cut and color of the peridot very, very much! If the clock hands are not always going to be there, then that is fine for me.

On the tourmalines I think the window in the middle of the first may bug me. I don't see it in the second one, and if you say the end bars are just because of the angle, then that is also good enough for me.

Thanks for being my quality contol!!

 

[fredflintstone]

How can you tell shallow stones? Does knowing measurements help? Are we looking for depth to be a certain percentage of width?

I also wanted to follow up with you on the pink/red irradiation of so much Afghan tourmaline. Are you finding that true of green and pink bicolor tourmaline like this too, or does the green mean they are more likely to be natural?

Stones are to shallow when there is an obvious window. Though measurements help a lot. If the depth is relatively low as compared to the length and width, you can be pretty sure it is windowed. But with that said, there a certain cuts and very talented lapidaries who can cut a shallow stone with no window. Your eyes are your best tools and the more you get experienced in buying gemstones the easier it is to discern what is a great cut, what is a good cut, what is a fair cut and what is a poor cut.

Only pink and red Tourmaline is either heated or irradiated from Afghanistan as far as I know.

 

[Odyssey44]

I bought the peridot! I'm very happy with it. It glows in bright light!

 

[Autumn in New England]

Oh yesssss... that is perfection!!!!!!!!

 

[Odyssey44]

Oh yesssss... that is perfection!!!!!!!!

My consultant (i.e. YOU) was right!!

 

[fredflintstone]

I bought the peridot! I'm very happy with it. It glows in bright light!

Nice Peridot.

You did good!

 

[PrecisionGem]

How can you tell shallow stones? Does knowing measurements help? Are we looking for depth to be a certain percentage of width?

Trying to determine if a stone is too shallow by measurements isn't really very reliable or practical. When most people refer to the depth of a stone, they are thinking from the table to the top of the pavilion. This measurement doesn't really give you useful information however, unless you know how much is in the crown [C] and how much in the pavilion

. A more useful dimension would be the pavilion depth

but this is actually hard to accurately measure.

Two stones could have the same width and overall depth, but one with a high crown and shallow pavilion which may show a window, and the other with a deeper pavilion that has no window.

The window comes from the pavilion angles being cut below the critical angle for the material. You can compensate for this with some tricks on the crown, but these will involve small tables and higher crown angles.

The best way to judge if a stone is too shallow is, as Fred pointed out, look at it.

 

[Odyssey44]

Nice Peridot.

You did good!

Thanks so much Fred! Appreciate all your guidance along the way!

 

[Odyssey44]

Trying to determine if a stone is too shallow by measurements isn't really very reliable or practical. When most people refer to the depth of a stone, they are thinking from the table to the top of the pavilion. This measurement doesn't really give you useful information however, unless you know how much is in the crown [C] and how much in the pavilion

. A more useful dimension would be the pavilion depth

but this is actually hard to accurately measure.

Two stones could have the same width and overall depth, but one with a high crown and shallow pavilion which may show a window, and the other with a deeper pavilion that has no window.

The window comes from the pavilion angles being cut below the critical angle for the material. You can compensate for this with some tricks on the crown, but these will involve small tables and higher crown angles.

The best way to judge if a stone is too shallow is, as Fred pointed out, look at it.

Super interesting. I will try to eyeball from now on to see that the pavilion is about 2/3 of overall depth.
I have seen some stones with a very flat looking crown, so maybe the pavilion is too deep. Other than not looking right, what kinds of flaws show up in the stone because of this?

 

[Odyssey44]

Ok, I also bought the second bicolor tourmaline I posted. This is the vendor photo.

It arrived and no matter what light, I could not recreate that vivid pink. The pink part did not brown out, it just always looked a kind of rusty-orangey color. Not at all what i was after. I am going to return this one and would not buy from this vendor again. The peridot vendor just got a bicolor in that seems vivid reddish pink, which is what I think I have to get for the pink part to actually look pink in regular indoor/outdoor conditions. So I will try again.

 

[VividRed]

Ok, I also bought the second bicolor tourmaline I posted. This is the vendor photo.

It arrived and no matter what light, I could not recreate that vivid pink. The pink part did not brown out, it just always looked a kind of rusty-orangey color. Not at all what i was after. I am going to return this one and would not buy from this vendor again. The peridot vendor just got a bicolor in that seems vivid reddish pink, which is what I think I have to get for the pink part to actually look pink in regular indoor/outdoor conditions. So I will try again.

I stopped buying on IG because of stuff like this. Never big purchases, mind you, but I got tired of the endless and pointless discussions about the unfair representation of color, which seems to be the only thing one can consistently rely on

 

[Odyssey44]

I stopped buying on IG because of stuff like this. Never big purchases, mind you, but I got tired of the endless and pointless discussions about the unfair representation of color, which seems to be the only thing one can consistently rely on

I have had 3 purchases I have been very disappointed in. 2 are tourmalines with part/all pink. Pink tourmalines might be something that should be an in-person purchase because they are so difficult. I have a couple of vendors now that I like, who will also show me accurate indoor videos and that I think answer my questions truthfully.

 

[VividRed]

I have had 3 purchases I have been very disappointed in. 2 are tourmalines with part/all pink. Pink tourmalines might be something that should be an in-person purchase because they are so difficult. I have a couple of vendors now that I like, who will also show me accurate indoor videos and that I think answer my questions truthfully.

They are difficult because the market is flooded with vendors who try to make their stones look more attractive than they are (nothing new per se, the scale is just on another level). The pictures you took are most like capturing the truer color and, to be fair, would not make a great pitch vs what the vendor showed

 

[Autumn in New England]

They are difficult because the market is flooded with vendors who try to make their stones look more attractive than they are (nothing new per se, the scale is just on another level). The pictures you took are most like capturing the truer color and, to be fair, would not make a great pitch vs what the vendor showed

Exactly... the online market is oversaturated, and with a mediocre inventory, the only way they can stand out from the crowd is with better photos, accuracy be damned.

OP, if you see these lighter-toned bicolors with vibrant color, you can almost bet your life they will be lackluster in person. That rusty color you're talking about is very common and, IMO, very undesirable. Try to aim for medium tone, as vivid saturation is more likely to come along with it. Of course, the prices will increase (and perhaps clarity will decrease). But I've found it's much easier to find a fine bi-color (pink/teal) than fine watermelon (red/green). And they can be really beautiful. Now if you're specifically looking for pastel, that's a different story. They can be very pleasant too, just a different animal. But the most valuable is going to have a rubellite color at one end (that never browns out) and a strong, pure green at the other. Again, medium tone... not too dark. I look forward to seeing the new one!

 

[Odyssey44]

I hate that rusty color and it is some kind of alchemy the way the photos show it as strong pink.
This is the picture of my next try. The vendor says this is the finest bicolor he has seen in 6 years. It is bigger than I wanted (did I really just say that??) at almost 14 cts, and a lot more expensive. What do you think? My most wanted colors are vivid hot pink (as opposed to red) and vivid green (as opposed to teal).

 

[Autumn in New England]

If it is that nice in person, then it is also the finest I have seen in a while!