Narrator: This small blue gemstone
is one of the rarest in the world.
And because of the unique way it forms in the earth,
benitoite sparkles even brighter than diamonds,
making it incredibly expensive.
A single carat can cost over $12,000.
But you can only really find this gem in one place.
So why is benitoite so hard to find?
And what makes it so expensive?
How is benitoite different from other gemstones?
It has a brighter vitreous luster.
Narrator: That means it looks like glass,
but brighter, shinier.
It also has a high dispersion, or fire,
meaning it can sparkle more than other gemstones.
Dave: So, here we are on the top of the mine.
Narrator: This is a private mine.
It's part of Benitoite Mining Company,
owned by John and Dave Schreiner.
The company is stationed here
because facet-grade benitoite can be found
in only one location:
San Benito County, California.
That's why it's the state's gem.
There have been microscopic deposits found in Japan.
But so far, this is the only place where you can find it
where it's actually big enough to hold in your hand
and to put in jewelry.
Narrator: Not knowing how rare it was,
miners used to extract benitoite just like any other gem,
with explosions and blunt force.
And now the supply is finite.
Gemstones like benitoite are generally scattered,
but sometimes there's a vein underground
where concentrated amounts of the gem collect.
Benitoite formed when an oceanic plate
and a crustal plate came together.
One plate slid under the other,
and water got trapped in the fault line.
Magma then intruded into the fault line
and mixed with the trapped water.
As cracks and veins formed in the surrounding rock,
the superheated mixture flowed into them.
Here, the rare element barium bound with titanium,
silica, and other elements.
Together, they formed benitoite.
But finding the gem is a bit of a guessing game.
And if John and Dave guess incorrectly, the cost is high.
To help them find where benitoite might be,
they look for this.
The white part of the rock is natrolite,
and the dark part, blueschist.
These are two minerals that surround
and protect benitoite.
If they see the white,
it may mean they've found a benitoite vein.
And when the vein breaks out onto the surface,
it's referred to as an outcrop.
A big vein, or a big outcrop, of benitoite was right here
and had fallen against the mountain.
That was dug out, dynamited.
All the material off the top of it's gone.
That doesn't mean there's not stones here.
They're all over the place.
Narrator: Yet a benitoite vein hasn't been found here
since the late 1990s.
So today, John and Dave are mining in a location
they think has potential.
They have to narrow down where they think the vein is,
because excavating and drilling is expensive,
and they can't afford to be wrong.
Core drilling alone will cost them $200,000.
John: Funding is always an issue.
Mining is not a cheap venture.
Normally that's what's holding us back,
just having the funds to actually move forward.
Narrator: So as they work up to that funding,
they're also working to confirm exactly where the vein is.
After they load all the material they excavated,
they can begin processing it
to see if there's a concentration of benitoite.
That starts with sorting.
This is the first stage of the wash plant.
Right over here is where the material
gets dumped in originally.
So, everything above inch and a half
gets stopped right there.
Narrator: After this, John can locate
larger specimens that need to be acid-etched,
where acid is used to carefully break off the benitoite
from its surroundings.
They also screen for everything under an eighth-inch,
and the sorted material goes up a long conveyor belt
to be washed in the trommel.
The trommel shakes and cleans the rocks
before they hit the black-light room.
Benitoite is fluorescent, so the Schreiners use UV light
to identify the gem without damaging it.
After, he screens and washes all the fluorescent pieces
and collects the best ones.
John: There's one of them.
That is a benitoite.
Narrator: Even though John found some good pieces
of benitoite, today's excavation was just OK.
John: This is good. We've done better.
Narrator: Still, he and Dave remain hopeful.
They're confident that they're getting really close
to locating that vein.
Finding another benitoite vein would be outstanding.
It would change a lot of things.
That is the direction we're going in
and that we want to go in.
It's financially hindering,
but we are getting there.
Narrator: But even if John and Dave find a vein,
it doesn't mean all the benitoite they excavate
can be sold for top dollar.
Benitoite is a naturally small gem, like diamonds,
so most of the rocks they find can't be faceted
into a clean, clear gem.
John: On average, you lose about
80% of the stone during the cutting process.
It also depends on how clean you want the stone to be.
Narrator: But the remarkable
and highly valuable properties of benitoite
make all this work worth it.
Starla: What's also very unique about benitoite
is that it is doubly refractive.
So when the light enters the stone, it splits into two rays.
Narrator: This creates a doubling effect,
giving benitoite a complex internal appearance.
Yet on the surface,
it looks like light bounces off the gem on all sides.
The depth these qualities create is enriched
by the stone's color, which shows in the price.
Starla: In a color gemstone is color.
Color, color, color is the first and last
and most important factor affecting value
in a color gemstone.
And depth also holds the color.
Like, a deeper stone can have a deeper color,
and that makes it more valuable.
The darker the color, the more valuable
the stone typically is.
It is amazing.
Anytime you look at something like this
and you think, "How in the world did this ever happen?"
That I could be holding something in my hand
that represents
such an amazing geological
formation and event,
and what had to happen for all of this to occur.