Pear Cut Bow Tie & Beryllium Questions

[endless_summer]

Hey Guys!

So, I have a couple of general questions (without a specific ring or stone in mind).

In your experience, do the bow ties that diamonds typically have in pear shapes show up as apparently in colored stones? Does the specific color minimize the effect at all (e.g., will it show more in yellow than in blue?). Any tricks to avoid them? I've read below 60% depth and they get larger, 62-63% is a bit of a sweet spot, and that 66%+ just results in a darker stone but minus the bow tie. Does that lw ratio on the pear impact it at all?

And…berylium, in regard to yellow sapphires - what are your thoughts? From what I gather, it's very typical for yellow sapphires to have been treated with beryllium - is it pervasive enough that one should assume beryllium if there has been heat, absent an AGL or GIA cert to say otherwise? And, I've read conflicting things about whether or not the color is stable - from: beryllium is permanent and the color is stable to beryllium-treated stones fade over time. I'm assuming it's best to avoid all together, but what has your experience taught you?

And, on yellow sapphires generally - I feel like a lot of them look to have a bit of an orange tint - is it possible find them in a more just yellow (like fancy light yellow/canary yellow) without the warmth that the orange brings to it?

Thanks so much for any thoughts, opinions, information you may have to share!

PS - I might have been inspired by pregcurious's new stone (please take it as flattery!)

 

[chrono]

Most coloured stone pear shapes will exhibit bowties. Depending on the cut, the size of the bowtie will vary. Depending on how light or dark the stone is, the bowtie can be prominent or less obvious. Darker stones (dark blue) typically do not show a bowtie as strongly as a lighter coloured stone (yellow). Unfortunately, depth% and/or ratio dictates practically nothing when attempting to predict the occurance or size of a bowtie.

For sapphires, BE diffusion is stable and permanent. I tend to be overly cautious and presume diffusion unless GIA or AGL says it is unheated or heat only. If the price is right and you like the stone, I have no issues with diffusion. Interesting that you've seen quite a few orangish yellows. My experience has been more greenish yellow rather than pure yellow.

 

[LD]

Pears don't just suffer from bow ties either You will often see pears that are lighter or darker at the tip. That's pretty common. I love pears but finding ones that are well cut can be challenging. No tip other than to use your eyes I'm afraid.

In terms of beryillium - years ago only the surface was diffused which would scratch off or fade. Now the treatment permeates the stone and is stable and permanent. As far as I know, they don't suffer from fading HOWEVER, are you taking about irradiation? In some stones (ie Kunzite) they can be irradiated but the colour fades over time.

The majority of lovely looking yellow sapphires are BE treated. If you see something that's a lovely yellow with little brown it probably has been treated. It's one of the few colour sapphires that's difficult to find untreated. However, you can find them and some of the more vanilla looking ones are scrumptious!

 

[minousbijoux]

In addition to what the previous posters have said, I would add that its not worth your while at all to focus on depths, but to just view whatever stones you are considering, because the bowtie will be evident. As to color affecting it, a bowtie is a bowtie regardless of color, though sometimes imo, lighter stones at least can take a bowtie better as they reflect more light back. In darker stones, it literally looks like someone turned off the color on the tip...

 

[pregcurious]

You can try to address bow ties (extinction) and general color variation in a sapphire pear by buying one with silk, like the stone you referred to. (Other posters, you can see my stone here: [URL='https://www.pricescope.com/community/threads/pear-sapphire.194201/']https://www.pricescope.com/community/threads/pear-sapphire.194201/[/URL])

I haven't seen many yellow sapphires that are orangey.

 

[minousbijoux]

I haven't seen many yellow sapphires that are orangey.

Its funny, because whenever someone describes sapphires this way, I immediately think of one particular vendor: ATG. I don't know if he specializes in them or what, but look at how many he has on this page! http://www.atggems.com/Photos_Sapphire2.htm

 

[minousbijoux]

and I hasten to add that to me, this particular color is a red flag for beryllium treatment; I always assume full treatment because nature alone seems to rarely produce this color.

 

[endless_summer]

Thanks all!

It must just be something about my monitor that makes me see a bit of orange - when I think of yellow, I think lemon colored; whereas with golden or almost honey, I see a bit of orange - I have no doubt that I'm probably throwing you all off using the wrong words or describing a monitor discrepancy

I do appreciate the thoughts on the pear cuts - I feel like with fancy shapes, there is no silver bullet, as I much as I wish that there were! I would love to go look at things in person, but B&M prices are beyond my reach, so I'm looking just from pics alone - it just means I can only pick vendors with no-questions-asked-type return policies. It is extremely helpful though to know what to look for - a quality like more color in the tip would be something that would take me a while to notice, let alone notice and think that it were the cut.

I really appreciate the information about the BE treatment - I really had read about it fading, and putting it into context about BE in the past versus now is really helpful for me. I have thought it safest to just assume all yellow sapphires are BE-treated, if heat, absent a lab cert, and from what I had read also thought to just avoid yellow sapphires all together because I was afraid of fading color.

Last question (hopefully for now) - can anyone explain the different between strong saturation and moderately strong saturation? Recognizing the vivid is ideal, is there an appreciable difference to the eye between these two? If a stone already has a medium-dark tone, how does saturation effect what the stone looks like? I saw the picture comparison one of you guys did with the blue sapphire and the 'awesome' caption and the photo-shopped version to show more or less saturation, and it looked like one was a soft violet whereas the other was blue. I feel like I'm missing the concept, other than vivid is the best, and the closer one gets to vivid, the better.

Thank you for taking the time to educate me and anyone else that might be reading - you really help a lot of folks out, and I appreciate it very much (you guys already helped me with the window!).

 

[pregcurious]

This thread explains saturation:

[URL='https://www.pricescope.com/community/threads/new-to-coloured-gemstone-buying-read-this-first.174284/']https://www.pricescope.com/community/threads/new-to-coloured-gemstone-buying-read-this-first.174284/[/URL]

 

[endless_summer]

Thanks Pregcurious - I have read the thread and just re-read it. I understand what the terms mean in theory - just trying to figure out if there is a difference that I or one would appreciate between moderately-strong and strong saturation, such that moderately-strong would not be a good choice. I recognize that its likely as hard for one to explain as it is for me to understand without having a number of real life in-person examples, but I just thought that I would try

There are two stones I'm thinking about - per NAGL appraisals (no other certs and both heat-treated, no other enhancement noted), both pear cut (1.3 lw, 61-62% depth), about the same face up size, between 3 and 4 carats, good cut/symmetry/polish, and transparent - but, one is dark yellow (no secondary color) with strong saturation (I think it may have a bit of a bow tie and the color does seem slightly more concentrated in the tip), and the other is medium-dark violetish blue (90% blue, 10% violet) with moderately strong saturation. The kicker is that each of them has a note of 5-10% windowing, though its not apparent to me from the pics, except on tilt angles, so I'm not quite sure how to interpret it. The yellow one looks like honey-colored sunshine, and there's just something about the particular blue that appeals to me.

If you or anyone has thoughts on the stats, I'd love to hear them, and if I pull the trigger on either of them, I'd certainly be posting pics upon arrival.

 

[LD]

Endless Summer - I have NEVER bought a coloured stone using stats. For coloured stones you need your eyes (and thankfully they're a free tool)! The reason is that stats only tell you a little - colour, uniformity of colour/tone and cut issues are much much more apparent with your eyes.

I'm going to show you examples of things to try to avoid.

The first set of photos below are examples of bow ties in pear cuts. You can see they appear either black or white.

The second photo shows you a beautiful gem but can you see how the tip is much darker? This can be either darker or lighter.

 

[minousbijoux]

Endless Summer - I have NEVER bought a coloured stone using stats. For coloured stones you need your eyes (and thankfully they're a free tool)! The reason is that stats only tell you a little - colour, uniformity of colour/tone and cut issues are much much more apparent with your eyes.

I'm going to show you examples of things to try to avoid.

The first set of photos below are examples of bow ties in pear cuts. You can see they appear either black or white.

The second photo shows you a beautiful gem but can you see how the tip is much darker? This can be either darker or lighter.

Yes! Let go of the stats, please and just decide when you see them. Make sure the vendor allows returns and then you're covered.

 

[endless_summer]

LD, the pictures are super helpful and help me to look for the pattern, even if less pronounced in vendor photos.

Minousbijoux - I promise I'm not attached to the stats - I was just hoping that they could be a good predictor or, at least, a rejection tool to make decisions before having something in hand

I'll use my eyes, and thank you both so much!

 

[minousbijoux]

LD, the pictures are super helpful and help me to look for the pattern, even if less pronounced in vendor photos.

Minousbijoux - I promise I'm not attached to the stats - I was just hoping that they could be a good predictor or, at least, a rejection tool to make decisions before having something in hand

I'll use my eyes, and thank you both so much!

You know one of the things I always do if I think its a likely possibility is to ask the vendor. The majority of vendors are honest and once they know something bothers you, they don't necessarily want you to buy it because they know its highly likely it will just get returned.

 

[endless_summer]

Thanks Minousbijoux - I had asked, and the seller just kind of never answered, but at least on of the stones, I'm pretty confident will have a fairly prominent bow tie most of the time, so I'll just skip that one. But, I did finally see an example of beautiful pear for sale today - the color was even through out, little to no bow tie, and no windowing even as the stone turned - so, of course, it's being sold for double my budget! At least, it's something to try to get close to

 

[minousbijoux]

Thanks Minousbijoux - I had asked, and the seller just kind of never answered, but at least on of the stones, I'm pretty confident will have a fairly prominent bow tie most of the time, so I'll just skip that one. But, I did finally see an example of beautiful pear for sale today - the color was even through out, little to no bow tie, and no windowing even as the stone turned - so, of course, it's being sold for double my budget! At least, it's something to try to get close to

I know you will agree, but that would be a huge red flag to me and enough to make me walk away from the vendor. Silence is very telling, I'm afraid.

 

[Lee Little]

Some writing mistakenly claims that beryllium treatment is the same as a dye and dyes can often fade, however, beryllium treatment is an element that has attached itself inside the molecular lattice thus it cannot be undone and cannot fade as it has become part of the stone. Dyes only fill voids, can often be removed and are not actually part of the stone.
The beryllium treated Sapphires come in many colors besides pure yellow including bright orange, red and even brilliant blues. The reds are not properly called Ruby even though they are red Corundum, Ruby has Chromium. Red Sapphires are usually orangish Red, I have not seen pinkish or purplish red ones. Best regards, Lee

 

[endless_summer]

Some writing mistakenly claims that beryllium treatment is the same as a dye and dyes can often fade, however, beryllium treatment is an element that has attached itself inside the molecular lattice thus it cannot be undone and cannot fade as it has become part of the stone. Dyes only fill voids, can often be removed and are not actually part of the stone.
The beryllium treated Sapphires come in many colors besides pure yellow including bright orange, red and even brilliant blues. The reds are not properly called Ruby even though they are red Corundum, Ruby has Chromium. Red Sapphires are usually orangish Red, I have not seen pinkish or purplish red ones. Best regards, Lee

That is a really nice explanation - thank you, Lee - I appreciate it.

 

[chrono]

I agree that a dye job is not the same as diffusion. Diffusion is stable and permanent but alters the sapphire greatly since the stone is brought almost to melting point for this treatment. The molecular structure is changed radically and this treatment is considered very invasive. It does, however, make a sapphire look very attractive with a low price point.