CosmicOpals
Notes from the bench

Blog

Opals, cutting, and how this shop came to be. Written at the same bench the stones come off.

Rough Ethiopian crystal opal — before any grinding begins, the stone is attached to a dop stick to control its angle against the wheel.
The bench · 3 min

Dopping: how to mount a stone for grinding

Before you grind a cab, you need to hold it. Here is how dopping works and why the alignment matters.

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Full-spectrum Ethiopian Welo opal rough — the raw material before any cutting begins.
The bench · 4 min

The cutting process: rough to cab

What happens between a piece of rough opal and a finished cabochon. The full sequence.

Excavated bentonite clay at the Rainbow Ridge mine in Virgin Valley, Nevada — a full day of digging before any finds come out.
History · 4 min · 1 views

How Virgin Valley opal is mined

The opal is in bentonite clay, not hard rock. Here is what a day of digging looks like on the claim.

Map of Australia showing the major opal mining regions: Lightning Ridge in NSW, Coober Pedy and Andamooka in South Australia, and Yowah in Queensland.
History · 4 min · 1 views

The opal fields of Australia

Lightning Ridge, Coober Pedy, Andamooka, the Queensland boulder fields — a map of where Australian opal comes from.

Dark-body Ethiopian opal — natural dark body and smoked material can look identical until you put the stone in water.
Opals · 4 min · 1 views

Smoked Ethiopian: what it is and how to spot it

One of the opal market's most common frauds. Here is how it works and how to test for it.

Carved Ethiopian crystal opal fish on white quartz and garnet matrix — the whole translucent body glows with blue and violet play-of-color.
The bench · 3 min

August on the bench

What's come through the shop this month, what got cut, and what's heading out the door.

A cabochon showing a dense field of tiny play-of-color points across the face — the pinfire or 'still water' pattern.
Opals · 3 min

Pin fire

Pinfire is the densest play-of-color pattern — thousands of tiny points packed across the face. The still water stone is one of the better examples on the bench.

A freshly unearthed Virgin Valley crystal opal just out of the bentonite clay, wet, color firing through the surface.
History · 3 min

Planning the fall trip

Virgin Valley in the fall. What the claim looks like in late summer, and what we go in expecting.

Dark opal rough held between fingers — the handling that wears stones comes from rings, not from being held.
The bench · 4 min

Opal care, practical

What actually damages opal, what doesn't, and what to do if you wear it every day.

Excavated bentonite clay and rock at the Rainbow Ridge opal mine in Virgin Valley, Nevada — the raw material of a digging day.
History · 4 min

Where opal comes from

Lightning Ridge, Coober Pedy, the Ethiopian Highlands, Virgin Valley. Different places, different stone.

Three slabs of Koroit boulder opal — dark Queensland ironstone with intricate opal color networks winding through the matrix.
Opals · 3 min

Koroit

Boulder opal from Queensland's ironstone country — where the matrix is the point, not the inconvenience.

A slab of rough Ethiopian Welo opal with the color bar exposed on the cut face — this becomes a solid cab or nothing.
Opals · 4 min

Solid, doublet, triplet

Three types of opal jewelry stone. The one question every buyer should ask before handing over money.

Rough dark Ethiopian opal with red and orange play-of-color — the color caught at one angle, one moment, one light position.
The bench · 3 min

The camera problem

Every opal photo lies a little. Here's what a camera can't capture and why it matters when you're buying.

Full-spectrum Ethiopian Welo opal rough showing red, orange, yellow, green, and blue play-of-color across the face.
Opals · 4 min

What opal costs and why

The price range in opal is enormous. Here's what actually drives value and what to look for at any budget.

Rough Ethiopian crystal opal — before any setting decision comes the question of what shape the finished stone will be.
The bench · 3 min · 1 views

Setting an opal

Bezel, prong, wire wrap — the setting choice affects how long the stone survives and how it looks. Here's what works.

Rough Ethiopian crystal opal photographed next to a U.S. quarter — the physical size reference that carat weight alone can't give you.
Opals · 3 min

What size means in opal

Carat weight tells you less about opal than it does about almost any other gem. Here's what matters instead.

Rough dark-body Ethiopian opal showing red and orange play-of-color against a near-black body — the contrast between the color and the ground is the story.
Opals · 3 min

Fire on black

The same play-of-color on a dark body and a light body are not the same thing. Here's why dark body opal looks the way it does.

Rough Ethiopian Welo crystal opal with green and red fire across its face, dark matrix attached at the back.
The bench · 3 min

What you see in the rough

Evaluating an uncut opal is a skill. Here's how to read a piece before the wheel touches it.

Ethiopian Welo opal rough with a warm honey-amber body, fire visible through the golden translucent body, most of the stone still in sandy matrix.
Opals · 3 min

The honey body

Body tone in opal is usually talked about on a black-to-white scale. Then there are the ones that don't fit the scale.

Rough Ethiopian black seam opal showing intense red and orange play-of-color on a very dark, near-black body.
Opals · 4 min

Ethiopian black seam

Not all dark opal comes from Lightning Ridge. Ethiopian black seam opal is its own thing.

Ethiopian Welo crystal opal rough with a translucent milky-lavender body, green and blue play-of-color showing through the stone, sandy matrix still attached at top.
Opals · 3 min

The crystal look

Crystal body tone is the most transparent opal gets. Light goes through it the way it goes through water.

Large rough Ethiopian Welo opal with vivid red, orange, and yellow play-of-color across a milky cream body, sandy matrix at edges.
Opals · 4 min

Reading red fire

Red is the rarest spectral color in play-of-color opal. Here's why, and what it looks like in rough.

Rough Ethiopian Welo crystal opal with vivid blue and green play-of-color, glassy transparent body, sandy matrix still attached.
The bench · 3 min

Blue in the rough

Blue-green fire in crystal opal — and why this piece is still sitting on the shelf.

Large rough Ethiopian Welo crystal opal with a gray body, red, green, and blue play-of-color running across the polished face.
Opals · 3 min

Gray body, full fire

The gray-bodied Ethiopian crystal opal that doesn't photograph the way it looks in hand.

Macro close-up of opal druze — tiny crystalline opal formations covering a surface, green and blue fire visible between the structures.
The bench · 4 min

How to read rough opal

Before anything gets cut, it gets watched. What you're actually looking for in rough, and why it matters.

Rough Ethiopian Welo opal held in a hand, green and blue fire visible through the translucent body.
The bench · 3 min

July on the bench

A look at what's come through the shop this month — rough in, rough evaluated, some of it cut.

Rough Ethiopian Welo opal on sandy matrix, green and blue fire visible through the translucent body.
Opals · 4 min

What opal actually is

Opal isn't a crystal. It isn't a mineral in the usual sense. Here's what the silica is actually doing.

A carved Native American headdress in boulder opal — intricate feather and bead detail in dark ironstone matrix with opal color peeking through.
The bench · 4 min

The headdress

Of every piece that's come off this bench, the headdress is probably the most hours per square inch.

A large Virgin Valley crystal opal photographed through its water dome — full-spectrum green, orange, and red fire, with a dark streak of petrified wood still embedded in the center.
History · 4 min

The Nevada dome

The biggest piece we've pulled from Virgin Valley lives in water permanently. Here's what's inside it — and why it will never be cut.

A wire-wrap pendant holding two opals in a single silver wire frame — a dark blue opal on the left and a lighter crystal opal with pinfire on the right, set in coiled fine silver wire against a quartz crystal.
The bench · 3 min

Wire wrapping: setting without heat

Standard settings use heat somewhere in the process. Opal doesn't like heat. Wire wrapping is how you set a stone cold.

Polished Queensland boulder opal slabs — dark ironstone matrix with Koroit-pattern color running through in ochre, brown, and flashes of green.
Opals · 4 min

Boulder opal: why the ironstone stays

Most opal work is about separating the color from its host rock. In Queensland boulder opal, the ironstone is the point.

A 25.8-carat piece of rough Ethiopian Welo opal on black — rolling red, orange, and green flash across a crystal body with matrix at the base.
The bench · 3 min

A fresh parcel on the bench

Nine pieces of Ethiopian Welo, 17 to 59 carats each. What goes through your mind before the wheel touches any of it.

Large raw Ethiopian Welo opal resting in quartz matrix — brilliant orange and green fire burns through a water-clear crystal body.
Opals · 4 min

Welo, Ethiopia: where the fire lives

Most of the gem world learned Ethiopian opal existed around 2008. Here's where it actually comes from — and what makes it different from everything else.

The potch-and-matrix back of a rough Ethiopian Welo opal held in fingers — sandy host rock visible at the top, a sliver of color showing at the bottom edge.
The bench · 3 min

What the back tells you

Everyone photographs the face. Turn a rough opal over and you learn what you're actually working with.

Two faceted Ethiopian crystal opal teardrops on a white foam pad — the left showing broad floral color, the right electric pinfire.
Opals · 3 min

Faceted opal: the other way to cut

Most opal cutters cab. Here's why — and the one type of material where faceting actually makes sense.

A small carved Ethiopian crystal opal turtle resting on chunks of white quartz — green and red fire runs through the body of the carving.
The bench · 3 min

When the stone tells you the shape

With a cab, the cutter decides the shape. With a carving, the color bar gets a vote.

A large polished Ethiopian Welo opal cabochon photographed against purple flowers and green foliage — red, green, and blue pinfire fires across the oval dome.
The bench · 4 min

Opal care: the actual list

Twenty-plus years of answering the same question. Here's what you actually need to know — and the one thing that will definitely damage any opal.

Rough Ethiopian Welo opal held in both hands — brilliant pink-red and yellow-green play-of-color blazing across the surface.
The bench · 3 min

How to read rough

Before a cut happens, there's a longer process. Here's what twenty years of lapidary work looks like in the evaluation stage.

Raw Ethiopian Welo opal rough showing intense orange and red fire against a dark background — vivid warm play-of-color in an uncut stone.
Opals · 3 min

Orange fire in Welo

Most Ethiopian opal plays blue and green. The pieces that throw orange are rare enough that when you find one in a parcel, you set it aside.

Rough Ethiopian Welo opal held between fingers over pinkish sandy ground — vivid red, pink, green, and orange play-of-color blazing across the translucent stone.
Opals · 3 min · 2 views

The opal that drinks water

Ethiopian Welo opal is hydrophane — it absorbs water, and the color goes flat when it dries out. Here's what that actually means.

Rough Ethiopian Welo opal held in the cutter's fingers — vivid blue and purple play-of-color.
History · 4 min

Twenty years to a name

CosmicOpals didn't start as a shop. It started as a rock habit in Santa Cruz that got out of hand.

A wet crystal opal slab fresh from the wash bucket at Rainbow Ridge, blue, green, and orange play-of-color on dark wet rock.
History · 6 min · 2 views

The claim in Virgin Valley

We don't just buy rough — once a year we go dig our own, on a ten-acre fire opal claim in the Nevada high desert.

Five polished Ethiopian Welo opal cabochons on black velvet — vivid pinfire play-of-color across each dome.
Opals · 4 min

What play-of-color actually is

The rainbow in an opal isn't pigment and it isn't a trick of polish. It's geometry, a few hundred nanometers at a time.

Polished freeform opal cabochon on weathered wood — pale crystal body with electric blue play-of-color.
The bench · 3 min

Why we list the cracks

Every listing we write names the sand, the cracks, the matrix. Here's why we'd rather lose a sale than skip that paragraph.