In the Steven Universe cartoon series, most of the characters are some kind of space alien gem or semi-precious rock. They don't just use the best-known gems, but dig deep into the collection drawers to pull out azurite, chalcedony, various kinds of agates, and even some questionable "gems" like flint.

This raises the question (or at least it does for me): which of the gems would make good lasers?

I've grouped the gems into four categories according to their pew-pew prospects, starting with:

D-tier

Sorry, no. Here's the thing about laser materials: light has to be able to travel through them. If it transmits light about as well as a brick, there's no way for light to survive and get stronger inside the gem. Even if the rock is a bit translucent, that's not good enough. Light will scatter away before it has a chance to form a strong laser beam.

Jasper (the Steven Universe character) looking miffed. The right half of the image shows a red laser beam hitting a chunk of jasper and being immediately absorbed.

These are your D-tier gems. They might be pretty rocks, but that's about it.

D-tier laser gems. Sorry, no. Lapis Lazuli Jasper Agate Snowflake Obsidian Obsidian Larimar Tiger's eye Serpentine Flint Chert Nephrite Jade Sardonyx Carnelian Pebbles Sugulite Malachite Rhodonite Azurite Spodumene Moonstone Chalcedony Desert glass Crysocolla

C-tier

At least these gems are clear and crystalline, so they won't stop a growing laser beam in its tracks. It might be possible to make a laser from these, but I don't know of anyone who's done it. A laser gem needs the ability to store energy and later release it as identical copies of the light that hit it. (This ability is called stimulated emission, and it's the SE in LASER.) Likely these gems can't do stimulated emission at all, or are really terrible at it.

Amethyst (the Steven Universe character) stomping placidly through a crystal cave. Right side of the image: A red laser beam hitting a faceted amethyst and passing through it.

Here are the C-tier laser gems. I'm sure they're trying their best.

C-tier laser gems. Unlikely. Rose Quartz Amethyst Peridot Aquamarine Topaz Zircon Rutile Sunstone Tourmaline Bixbite Albite Titanite Cherry Quartz Angel Aura Quartz

B-tier

These are bona fide laser gems. They may not be the most popular laser materials, but at least some researchers have managed to make lasers out of them. They're clear enough not to kill a growing laser beam, and they have some ability to do stimulated emission (or to host a material that can do stimulated emission). I'm presenting them from least to most promising.

Spinel

She barely makes the cut as a laser material. A couple of papers over the years have looked into spinel as a laser material and shown some promising properties. The fact that they didn't follow with more papers or lasers probably means that spinel was a pain to work with for some reason.

Spinel (from Steven Universe) looking triumphant. Next to her is the title and abstract of a 2006 paper "Potential candidate for new tunable solid-state laser between 1 and 2 micrometers: Ni 2+ -doped MgAl2O4 spinel grown by the micro-pulling-down-method.

Emerald

I found a couple of papers from the 1980s that made lasers from emerald, but they must not have been very good ones because I've found nothing since.

Emerald (the character from Steven Universe) looking vaguely excited. On the right is a 1987 paper titled "Highly Efficient Emerald Laser".

Fluorite

One of the first laser crystals was fluorite with uranium added! It didn't work very well, plus, uranium. Fluorite is hardly ever used for lasers anymore, but it can be made into laser components like lenses and windows.

Fluorite, the many-eyed, many-gemmed Steven Universe character, with a 1962 paper from Physical Review Letters about using uranium doped fluorite in masers (and optical masers, which are now called masers).

Pearl

This is a surprise answer. With Pearl's cloudiness you would think she would be D-tier, but she has a regular microstructure (from all that time being built layer by layer inside a mollusk) that can help form a laser cavity. According to Mandal et al (2022) if you form her into a flat sheet and soak her with fluorescent dye, then energize her with a green laser, you can get yellow laser light out.

Pearl looking serene next to an extremely busy figure from a laser paper with literally 22 subfigures and 5 more sub-sub-figures. It shows that they got weak yellow laser light out.

Opal

Similarly to Pearl alone, opal is cloudy but made of regular microstructures that can help make a laser cavity. Like with Pearl, you'd have to soak her with dye and energize her with another laser, but you might get some laser light out.

Opal, with her six arms and dual-wielded weapons, hovers majestically above the ground. On the right is a 2008 paper called "Tunable single-mode photonic lasing from zirconia inverse opal photonic crystals"
B-Tier Laser Gems. Someone, somewhere, has made them into lasers. Spinel, Emerald, Fluorite, Pearl, Opal

A-tier

Unquestionably laser material, and they are promising as lasers. Even if they're only in research labs so far, they have the potential to be more than scientific curiosities.

Diamond

People have made lasers from diamond, though they're still not very common. With their excellent thermal conductivity, the diamonds might one day make powerful lasers.

Silhouettes of white, yellow, blue, and pink diamond characters, shown next to a 2024 article "Unlocking the power: how crystal size transforms diamond lasers".

As-yet-hypothetical Bismuth - Desert Glass fusion

Bismuth is so opaque that you would expect her to be D-tier. But if she's distributed throughout glass fibers, she can help turn them into infrared fiber lasers. So far they're not common, but watch this space!

The bismuth character, colored in greens and desert tones, with an extra set of eyes indicating she's a fusion. Her head is on the end of a long green body (mostly out of view). To the right is a research article from 2024 titled "Supermode lasing and light amplification in multicore bismuth-doped fiber"
my rendition of what a bismuth/desert glass fusion might look like.
A-Tier laser gems. Decent laser materials! Diamond, Bismuth/Desert Glass fusion

S-tier

These are not only laser materials, they are legendary ones.

Ruby

Quintessential laser gem. In fact, the first visible laser was made of ruby. The laser that was menacing James Bond in Goldfinger? Ruby. Emitting a gorgeous red laser beam and still useful for certain hair-removal procedures, Ruby has earned her place among top tier laser gems.

Left: Garnet (the character) looking triumphant and strong while surrounded by red laser beams. Right: James Bond being threatened with a red laser in the movie Goldfinger.

Sapphire

Some of the most advanced lasers are made of sapphire. Medical and research lasers made of titanium sapphire make pulses of light so intense that during the brief period of time they exist, they carry more power than the world's power plants combined.

Left: Sapphire looking fierce, surrounded by red laser beams. Right: the inside of a laser, viewed through a giant titanium sapphire crystal. The laser appears to be off, but there are cool blue reflections from somewhere, and the crystal is a lovely magenta color.
Image on the right is a real titanium sapphire crystal in the giant ZEUS laser at the University of Michigan. Unlike many sapphires, titanium sapphire crystals are pink, and they emit infrared light. Photo by Marcin Szczepanski

Garnet

Combined, the laser power duo Ruby and Sapphire turn into another god-tier laser gem, Garnet. In fact, garnets in various forms can make intense pulsed lasers of all colors. They're used in dentistry, hair removal, research, and more. Ruby, sapphire, and garnet are such great laser materials that I can't help but wonder whether this is why writer Rebecca Sugar associated them with each other. Garnet's even wearing laser goggles! I propose there should be an entire new set of Garnet characters with various impurities and colors, each with specific powers.

The character Garnet raises her impressive glowing hands, while surrounded by six red laser beams. Right: A photo of an Nd:YAG laser (neodymium doped yttrium aluminum garnet) in a research lab. Much of the laser is glowing white because of the weird ceramic reflectors they were using. Unusual but very cool looking.
Right image: Figure 3 from 2012 conference paper "Development of 490 W average power long pulse Nd:YAG laser based on diffuse ceramic reflectors".

Alexandrite

In the show, Garnet combines with Amethyst and Pearl to make a giant being that happens to be another great laser crystal. Alexandrite can emit high-energy pulses of infrared laser light, used in laser hair removal.

Right image: an alexandrite laser system for hair removal. System shown is from Perfectlaser.
S-tier laser gems - legendary lasers. Ruby, sapphire, garnet, and alexandrite

I'm not done with laser gems, though! There are a couple of other minerals that aren't currently in Steven Universe, but since they are laser materials I propose they should be in future series. These are:

Perovskite

As a mineral, perovskite makes grey, shiny materials. There are perovskite lasers in research labs, where people love that they are highly customizable. If Perovskite were a character, she'd be an A-tier laser material.

Xenotime

The mineral xenotime makes very cool-looking brown-marbled black crystals that are sometimes radioactive. It's a major source of the element erbium. Erbium-doped glass fibers make powerful lasers and laser amplifiers, which is why we need a Xenotime character so she can fuse with Desert Glass and be very powerful.

Wakefieldite (also known as ytterbium orthovanadate)

As a mineral, wakefieldite makes small crystals whose color varies from yellow to pink to brown to black based on the exact elements involved. It makes extremely powerful pulses of infrared light, and is used for machining. Wakefieldite would be a rare but bonafide S-tier.

Conclusion

There is a clear difference between the different laser gems, allowing me to easily rank them into tiers. The S-tier results in particular leave me with one question: is writer Rebecca Sugar into lasers? Because if not, it's a huge coincidence!

Let me know if I left any major characters out of the ranking!

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