January 24 Through February 4—TUCSON, ARIZONA: Annual show
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 Post subject: Weird and interesting synthetics
PostPosted: Thu Nov 10, 2022 9:24 pm 
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Hi everyone. I haven't been posting as much, and the big reason has been that it's been a really busy year. Starting around march my brother and I have gone all-in on selling lab-created stones, particularly weird and exciting industrial materials repurposed for gem usage. That's gone rather well so far, and we're actually going to be selling at Tucson this year (Y13, 22nd street's new north tent). But it keeps bugging me that I haven't posted about it here, so I'm finally getting started.

It may take me a bit to get more detailed information filled in since it's a lot of photos, etc. I'm going to start with my favorites.

First up are what we call 'lumogarnets'--these are lab-created garnets with extreme fluorescence which are typically used to help detect radiation (a broader class of crystals known as 'scintillators'). It turns out it is difficult to directly detect things like x-rays and gamma rays, but easy to detect visible light, so if you want a digital gamma ray sensor (ie, for a PET scanner) you get an array of light detectors like you'd have in a normal digital camera and then put long square pixels of something fluorescent in front of them. If a gamma ray hits it lights the pixel up and the sensor can easily detect that, while also being shielded from being pizza blasted by radiation.


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Ultra bright neon yellow Ce:YAG will be familiar to some gemologists--its industrial use goes back to the 70s iirc, with gem usage not long after. This material is sometimes directly grown for gem usage (or the similar but cheaper-to-grow YAC, yttrium aluminum ceramic), but scientific-grade material is highly optimized and glows much brighter. However things have continued to advance beyond the limits of YAG, with two further generations with even cooler properties!
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The first of these is Ce:LuAG, lutetium aluminum garnet. It is much like YAG in base properties: hardness 8.5, slightly higher RI of 1.84, all around good to cut and polish. It has a higher SG of 6.7 making it pretty hefty, and its base and fluorescent colors are both a neon yellow-green. Its output isn't really much higher than Ce:YAG in terms of photons, but the eye being more sensitive to green means it looks significantly brighter. This might be our number one gem--it has a strong eye-grabbing quality.
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But there's an even newer one! Introduced to industry in 2014 (and to gems just this year by us) is Ce:GAGG! This is an evolution of GGG with added aluminum, taking its hardness all the way up to 8. It has excellent optical properties too, though I don't remember the numbers off the top of my head--not quite as crazy as GGG but still good. It is yellow, similar to Ce:YAG but noticeably brighter to the eye (and much brighter in base specs). It also has another cool feature: it can glow in the dark! They actually work hard to suppress this so most of them only glow a bit, but occasionally we have found a piece where the chemistry was mixed up and it can actually glow in the dark fairly well.
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And to cap off the lumogarnets we have two that are a bit different. First up is Cr:YAG, which is actually not used as a scintillator at all, but as a q-switch in lasers. Some form of this material was known and documented in the gem world back when YAG was a bigger player in the synthetic space, and its best property was briefly noted though not elaborated on: it has a rich, tsavorite-green base paired with very strong red fluorescence. When you mix those together you end up with a stone that shows flashes of both, with one or the other dominating based on light spectrum, light angle and background color (black backgrounds favor red, white favor green). We call these 'christmas garnets' for obvious reasons.
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There is also the much more obscure Pr:LuAG, or 'christmas LuAG'. It has a pale green base and strong salmon fluorescence under blue light, as well as green fluorescence under UV. The combination gives you a similar look to Christmas YAG, but with a paler green and salmon color combo.

That's it for the lumogarnets (so far! we're always looking for more). I've got a lot more weird and interesting stuff though.

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 Post subject: Re: Weird and interesting synthetics
PostPosted: Mon Nov 14, 2022 6:49 pm 
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These have been my vice in 2022, lol. I've purchase a new UV flashlight just for these stones.

What started out as a plan to just pick up one as a random "fun" stone has become a bit of an addiction. I now have a collection of these weird synthetics from Stephen and have been sharing them around the office with my staff all year. Once my wife found out, she has claimed several for herself as well :lol:

Looking forward to seeing more in Tucson!

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 Post subject: Re: Weird and interesting synthetics
PostPosted: Mon Nov 14, 2022 9:37 pm 
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Interesting, yes!
Spooky, :shock: more than a little bit.


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 Post subject: Re: Weird and interesting synthetics
PostPosted: Thu Nov 17, 2022 12:22 pm 
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I got a coupla nice pieces from you as well.

I work with scintillators, but I've to admit that for my applications (XR micro-imaging) LuAG is superior to Ce:YAG. :D The scintillators trend in my field seems to go towards CsI, somehow. Which is not something I'd like to facet, since it does not like water too much... :wink:

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 Post subject: Re: Weird and interesting synthetics
PostPosted: Thu Nov 17, 2022 3:11 pm 
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That's really cool! I'll admit I'm curious about the ruby being bomarded with x-rays.
Yeah, CsI is one of those that we have to keep away. Anything water soluble or toxic, of which there are a few. Fortunately they haven't been too hard to avoid.

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 Post subject: Re: Weird and interesting synthetics
PostPosted: Tue Nov 22, 2022 4:57 am 
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Well, the ruby was a test for building sapphire windows for specific XR energies. I needed a monocrystal with a variable thickness in the field of view, ideally a cone (to be able to spin it), and the pavillion of a faceted ruby was the quickest solution to that problem (I can also test the 3D reconstruction of it, which was one of the tests). It survived the XR beam (synchrotron source) unaffected.

I had "Himalayan salt" samples turning brown and then black, in the past, when irradiate with that kind of beam.

There is a problem with optical glass, e.g. microscope objectives (which is bad :lol: ). The radiation causes browning of the lens, but you can reverse it with (SW)UV light. It also happened with my borosilicate glass windows.

I'm keeping your LuAG piece for when I'm inspired, but I really want to cut that Cr:YAG. Still not sure if I want to make a single chonker stone, or split it into two small and one large piece, as the rough seems to suggest. But I have to find a fitting design as well. You have some nice materials for sale.

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 Post subject: Re: Weird and interesting synthetics
PostPosted: Mon Nov 28, 2022 10:19 pm 
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I'm so glad I kept asking you two to keep finding these weird synthetics for me - you've turned into the major player of rare synthetics in the market! Definitely a solid replacement for the niche Uriah used to fill. :D

Now let's start running some custom growth runs! :mrgreen:


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 Post subject: Re: Weird and interesting synthetics
PostPosted: Mon Jan 09, 2023 3:22 am 
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Not only are the Christmas garnets interesting, but they provided me with some insight into how light travels through a gem. Sure, there are computer programs that do that, but it's more intuitive when you can see it in real time.


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