How to read an opal: what patterns and colors drive the price

I own Gem Masters, LLC in Spokane, Washington, and I am a guest on this page. Fasika Kassa, who founded Mercy Gems, has been around Ethiopian opal a great deal longer than I have. Most of what I know about these stones I learned standing next to him at a table. This is one of those conversations.

It was the end of a show day. The room was emptying, the light in the windows had gone gray, and we were supposed to be packing up. Instead Fasika had a tray of opals out again, because an hour earlier a man had stopped at our table and asked the question everybody asks.

He had picked up two stones of about the same size and read the cards. One cost several times what the other did. “They’re both opals,” he said. “What am I missing?”

“He was missing the light,” Fasika said, and he reached over and switched off the lamp.

Switch off the lamp

Under a jeweler’s lamp, every opal on the table looks like a firework. Take the lamp away and most of them go quiet. A few keep glowing in the flat light of the room as if somebody had left a battery in them.

“That one,” Fasika said. A stone in his palm was still throwing green across his fingers. “Brightness first. Always.”

Graders have five words for it: faint, dull, bright, very bright and brilliant. I used to think color was what you paid for. It took me a few expensive lessons to learn that a brilliant stone in ordinary colors will outsell a sleepy stone in rare ones, every time.

The body of the stone

Then he turned the stones face up and told me to forget the fire and look at the stone itself. That is the base color, and it runs from black, through semi-black, to white. A crystal opal is clear enough to see down into. A semi-crystal is a step cloudier, like frosted glass.

“This is what we are known for,” he said, and held a crystal stone up to the window. The fire hung inside it at different depths, like something floating in water. Most opal from Welo has a light base like that one. A dark base makes the fire jump, which is why black opal is king everywhere opal is sold, but a naturally dark stone from Welo is an uncommon thing.

So I asked him about the best dark stone he had ever handled. Every opal man has one. His was a black opal, dark all the way through, and big. He held his fingers apart to show me how big, and I told him I did not believe him.

Fasika laughed. “I’ve still never seen a black opal of that size again.”

That is how rare the real thing is. It is also why you ask questions when somebody offers you a whole parcel of black Ethiopian opal at a friendly price. Some of it has been smoked to darken it. It can be pretty. It is not worth what a natural stone is worth, and a seller should tell you which one you are holding. For the record, none of the opals Mercy Gems sells are treated.

Red is the one you chase

I asked which color he looks for, and he gave me a look, because I already knew. Red. Red is the rarest fire in an opal, then orange, then green, and blue is the most common. It comes down to the tiny spheres of silica the stone is built from. The large ones that throw red do not form as often.

“But,” he said, and held up a finger, because with Fasika there is always a but. “A bright green one beats a tired red one. Do not buy the word red. Buy what you see.”

What we both like best is a stone that cannot make up its mind. You turn it and it goes from green to orange to a flash of red and back again. Graders call three or more colors multicolor. I call it the reason I stay too long at the table.

Patterns, and the word everybody overuses

The patterns have names, and learning them is half the fun. Pinfire is a sky full of tiny points, and it is the one you will see most. Then come the bigger moves: flashfire in broad patches, broadflash in whole sheets, and the rolling flash, where a single sheet of color slides across the stone as you tip it, like a searchlight.

“Harlequin,” I said, because I wanted to hear him say it.

He was shaking his head before I finished. A true harlequin is a tidy patchwork of blocks, like a checkerboard, and it is the rarest pattern there is. It is also the most abused word in the business. “If everybody who says harlequin had a harlequin,” he said, “it would not be rare.”

Then he found what he was looking for in the tray and slid it under my loupe. Honeycomb: little cells of color with fine lines between them, like something bees built. That pattern belongs to Ethiopia. When it comes in a bright stone, people stop walking.

The rule under all of it is simple. Big, clear patches are worth more than small scattered dots, and a rare pattern adds a real premium. But only on a bright stone. A dull harlequin is still a dull opal.

Now turn it

“You are holding it like a photograph,” he told me. “It is not a photograph.”

An opal has to move. Some light up across the whole face. Some have dead patches where nothing happens. Some only fire when you tilt them just so, and go blank when you look at them straight on, which is exactly how they will sit in a ring. The ones that show from every angle are the ones worth paying for. This is why we film every stone turning, and why I will not buy an opal from a single still picture.

The glass of water

Here is the Welo story that happens to somebody every year. Much of this opal is hydrophane, which means it drinks. Drop one in a glass of water and it can turn as clear as a marble and lose its fire completely. The first time you watch that happen, your stomach goes with it. Then, over the next days, the stone dries out and the fire comes back.

“So do not wash the dishes in it,” Fasika said. Keep it away from water, oils and perfume, and it will behave.

So what did the man miss?

By now the room was empty and we had packed nothing. I went back to the two stones the man had asked about.

They were the same size, near enough. Both were solid opal, which matters, because a doublet or a triplet is only a thin slice of opal glued to a backing and is a much cheaper thing. Both were cut as clean domes with no cracks. But one glowed in the dark room, and the other needed the lamp. One showed red, and the other only blue and green. One had broad patches of color across its whole face, and the other had pinfire that faded toward one edge.

Every one of those is a step up in price, and the steps stack.

When I price a stone I start with the GemGuide, which gives me a range for the type and the grade. Fasika starts with the stone. We usually end up in the same place, which is either a good sign or proof that I have been listening.

What I wrote on the back of a show card

1. Ask what it is. Solid, natural and untreated, or something else.
2. Brightness. Switch off the lamp. Faint, dull, bright, very bright or brilliant.
3. Base color. Black, semi-black, crystal, semi-crystal or white.
4. Fire color. Is there red, and how many colors are there?
5. Pattern. Dots, sheets, or one of the rare ones.
6. Turn it. The whole face, from every angle.
7. Cut and condition. A good dome, no cracks and no crazing.

If you want to try it, pick any stone in the shop, watch its video, and run down the list. Then message us and tell us what you saw. We will tell you what we see.