At Turtle’s Hoard we specialize in lab-made gems that were produced for scientific and industrial purposes.  These include rare crystals that haven’t been seen in the gem trade before, as well as old classics which have been grown with extreme care and purity. Here’s a little info on some of the crystals we have in stock!

Material properties


"Lumogarnet" is a term that describes any highly fluorescent garnet - specifically, one where the fluorescence contributes significantly to the normal appearance of a cut stone.  There are several different varieties with unique compositions and properties.  All of them glow under both UV and blue light, and some of them will even glow in the dark!

We'll start with the cerium-doped lumogarnets, which are the brightest stones we have.  These stones were designed to detect high energy radiation by fluorescing whenever an x-ray or gamma-ray hit them. However, they're so sensitive that they also glow when UV light or blue light hits them.  Under indirect sunlight they glow so bright that they look like they've been photoshopped into real life.


Lutetium Aluminum Garnet

LuAG has an intense neon-green fluorescence which is incredibly appealing.  This photos is of the biggest known faceted LuAG in the world, cut by Eric Bardwil. It currently lives in the lab where it was grown.


Gadolinium Aluminum Gallium Garnet

GAGG is paramagnetic, so you can actually pick it up with a rare earth magnet! While all GAGG:Ce have at least a little bit of glow-in-the dark phosphorescence, the best glowers are visible for hours.


Yttrium Aluminum Garnet

YAG is a classic lab stone, with the purest yellow of the lumogarnets. It glows so bright that the first time I saw one, I scanned it with my Geiger counter just to be sure it wasn't radioactive (it wasn't).

Christmas Garnets

Christmas garnets are a kind of lumogarnet where the green base color of the stone doesn't match the red fluorescent color.  The result is an amazing mixture of both colors, which varies depending upon the angle.  There are two varieties of Christmas Garnet.  Cr:YAG has chromium in it, and is used in lasers as both the core laser crystal, and as a 'Q-switch' (which is a component that prevents the laser from firing until it's fully charged up, allowing for powerful pulsed lasers).  Pr:LuAG has praseodynium in it, and is a radiation detecting scintillator crystal.  It has an unusual dual fluorescence - it glows red when exposed to blue light, but glows green under UV!


Lutetium Aluminum Garnet

LuAG:Pr is an alternate scintillator material to LuAG:Ce. With a paler green base and orange/salmon fluorescence, it's a more pastel christmas garnet than Cr:YAG


Yttrium Aluminum Garnet

With an intense green base color, and strong red fluorescence YAG:Cr has an amazing and unique look not found in any other gemstone. This crystal is used as a 'Q-switch' in pulsed lasers - basically, it helps charge up the energy so it can be released all at once in extremely powerful bursts.

Color Change Gems

Crystals with rare earth elements often show color changes under different lighting, due to having very different responses to different frequencies of light. 


Purple Nd:YAG is one of the original commerically produced laser crystals. In recent years, additional codopants (including Ce and others) have been added, widening the range of colors to include peach and pinks. They also glow under UV!


Erbium YAG is another laser crystal, which shows a fantastic color change between pink and orange, and showing a rich padparadscha orange-pink under mixed lighting.

Other Lab Crystals


Blue Sapphire


Ruby and sapphire have long histories of synthetic production. Czochralski crystal growing was first developed largely to produce laser-quality rubies – old flame fusion rubies weren’t good enough because any impurities would get caught in the beam of the laser and shatter the crystal. We have classic red laser ruby (colored with Chromium), pink titanium laser sapphire, plus some Czochralski-pulled blue sapphire grown for optical filters.

Lithium Niobate

Lithium Tantalate

Bismuth Germanate

Several crystals are used for opto-electronics, converting between optical and electrical channels.  BGO, Lithium Niobate, and Lithium Tantalate are found in cellphones, fiber optic networks, and motion sensors - all of them have extremely high dispersion, making them throw rainbows when faceted.  


Last by not least, moissanite (also known as silicon carbide) is used in computer chips, LEDs, power tools and, of course, to cut gemstones.