ANDREA LI

LIMITED COLLECTIONS

Moonstone vs Pearl
Gemstone
Guide



Pearl · Moonstone

The same glow, two different stones

They are mistaken for each other all the time. Tap a marker to see what gives each its light, and how to tell them apart.

Pearl

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2
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Moonstone

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2
3

Tap a marker

A pearl and a moonstone can look almost identical at a glance. The difference is where the light comes from. Tap a marker on either stone to see it.

Illustrative, not a photograph.

 
 

Andrea Li

andreali.com

Gemstone Profile

Pearl vs Moonstone

Pearl

Organic Gem

Moonstone

Mineral Gem

Formation

Pearl

Layers of nacre build around an irritant inside a living mollusk, slowly, into a cultured or natural pearl.

Moonstone

A feldspar mineral that forms and grows within rock over long stretches of geological time.

Composition

Pearl

Nacre (aragonite and conchiolin). An organic origin, grown by a living creature.

Moonstone

Feldspar (orthoclase and albite). A mineral formation, grown in stone.

Hardness (Mohs Scale)
2.5 to 4.5
6 to 6.5
12345678910
Soft and delicate
Medium hardness
Luster & Phenomena

Pearl

A group of pearls: South Sea, Tahitian, freshwater, and Akoya

Surface sheen. Light reflects off the surface as orient, and through the sub-surface layers as overtone.

Moonstone

A group of moonstones: rainbow, peach, grey, and blue sheen

Adularescence, also called schiller. Light scatters between microscopic layers into a floating, ethereal glow.

Varieties

Pearl

Akoya pearl

Akoya

Classic white and cream.

South Sea pearl

South Sea

Luminous white and golden.

Tahitian pearl

Tahitian

Peacock and black.

Freshwater pearl

Freshwater

Many colors and shapes.

Moonstone

Blue sheen moonstone

Blue Sheen

A floating blue glow.

Rainbow moonstone

Rainbow

Multi-color flash, a labradorite.

Peach moonstone

Peach

Warm, soft tones.

Grey moonstone

Grey

Cool, subtle glow.

Symbolism

Pearl

Purity, wisdom, and new beginnings.

Moonstone

Intuition, calm, and connection.

Discover more at

andreali.com

Andrea Li

This stone is part of my pastel gemstone collection, one-of-a-kind pieces handcrafted in Denver.

 

A pearl and a moonstone can sit side by side and look like the same stone. Both glow with a soft, low light that seems to come from somewhere inside. People mix them up constantly. But they are not even close to the same thing: one is made by an animal, the other is made by the earth, and once you know where each one's light comes from, you will never confuse them again.

I set both. Pearls are one of the two stones in nearly every piece I make, and moonstone has carried whole collections. Here is how I tell them apart at the bench, and how you can tell them apart in your hand.

At a glance

PearlMoonstone
What it isOrganic. Made by a mollusk.Mineral. A feldspar, formed in the earth.
The glowLustre (surface sheen) plus orient (a faint rainbow play)Adularescence (a blue-white light that floats and drifts)
TransparencyOpaque. Light does not pass through.Translucent. Light passes in and scatters.
Hardness (Mohs)2.5 to 4.5. Soft.6 to 6.5. Harder, but it cleaves.
ColorsWhite, cream, pink, gold, grey, blackColorless to white body, with a blue or rainbow sheen
SourceMollusks, farmed and wild, worldwideSri Lanka, India, Madagascar, and more
BirthstoneJuneJune
CareSoft, porous, hates acid and heat. Last on, first off.Tougher surface, but brittle. Protect from knocks.

The glow is the giveaway

If you only learn one thing, learn this: look at where the light lives.

On a pearl, the light sits on the surface. That soft, satiny shine is called lustre, and it is just light bouncing off the smooth, layered nacre the mollusk builds up. On a good pearl you may also see orient, the faint rainbow play that seems to dance on or just beneath the surface, like the colors in a film of oil on water. Lustre is the sheen; orient is the rainbow. Together they make a pearl's glow, and all of it reads as warm and solid, because no light passes through.

On a moonstone, the light comes from inside. That floating blue-white glow is called adularescence, and it drifts across the stone as you tilt it. It happens because moonstone is built from microscopically thin layers, and light scatters between them, so the glow looks like it is hovering just under the surface rather than sitting on top. No pearl does this. The moment you see light move as you tilt the stone, you are holding a moonstone.

A note on the words: you may hear the term auralescence (sometimes misspelled auralecence) used in the gem community to describe that glowing, almost alive quality in stones like opals and moonstones. It is a lovely word, but an informal one. The proper terms are orient for a pearl's iridescence, adularescence for a moonstone's floating light, and play-of-color for an opal's flashes. Same family of magic, three different mechanisms.

What each one actually is

A pearl is organic. It is the only gem made by a living creature. A mollusk coats an irritant inside its shell with layer after layer of nacre, the same material that lines the shell, until a pearl forms. That is why no two pearls are ever truly identical, and why pearls are soft: nacre is delicate.

A moonstone is a mineral. It belongs to the feldspar family, the most common mineral group in the earth's crust, and it forms as two kinds of feldspar separate into thin, alternating layers as the stone cools. Those layers are what scatter the light into that blue glow. It is harder than a pearl, but feldspar cleaves, meaning it can split cleanly along its internal planes if it takes a sharp knock.

Durability and care, from the bench

This is where setting them teaches you the difference fast. A pearl is soft and porous, so it has to be protected from heat, from acids, even from perfume and hairspray. A moonstone has a tougher surface but it is brittle, so the danger is a sharp impact rather than a scratch.

From the bench

The drilled hole tells the whole story. When I need to widen a pearl's hole, or drill one where none existed, I use a specialized pearl drill. I did exactly that for a pair of cufflinks in Loretta's commission, drilling fresh holes into two Akoya baroque pearls so I could seat them onto little fabricated sterling silver pegs. A moonstone will not forgive that. To widen a moonstone's hole I switch to a diamond bit and work with the stone submerged underwater, so the friction stays cool and lubricated and the stone is far less likely to crack. And here is what I trust most: in all my years weaving stones into clusters, a pearl has never once broken on me. Gemstones do. I keep a bag of broken stones in my desk, casualties of being stressed at the junction where they get wired in, and moonstone is in that bag, because the same inclusions that give it character also let it cleave right where the hole is drilled. A pearl, as soft and organic as it is, has never failed me.

For the wearer, the rule of thumb is the same for both, for opposite reasons. Pearls go on last and come off first so they never meet perfume or lotion. Moonstones can take daily wear but should be kept from hard knocks against other jewelry. To clean either one, skip the ultrasonic cleaner and skip heat. Neither stone tolerates them, and honestly I would not put any of my pieces through them. Warm water, a soft toothbrush, and a drop of Dawn lift away the oils and dust that dull a piece, and the polishing cloth tucked into every order brings the metal back to life.

Which one is for you

Here is the happy accident: both pearl and moonstone are June birthstones, so whichever speaks to you, you are covered.

Reach for a pearl if you love a warm, classic, dressed-up glow, the kind of light that has meant elegance for centuries. Reach for a moonstone if you are drawn to something cooler, more mysterious, a little otherworldly, with that blue light that moves when you do. One is the moon's reflection on calm water; the other is the moon itself.

 

The four pearl types, side by side

Saltwater types are named for where they are farmed. All freshwater pearls come from China. Every pearl farmed and sold today is cultured.

TypeOysterKnown forStrand price, retail
Akoya Saltwater The first pearl ever cultivated. Smaller, classically round, white and metallic shades. $300 to $10,000 and above
South Sea Pinctada maxima Size, and exceptional golden color. $1,000 to $100,000 and above
Tahitian Pinctada margaritifera, the black lipped oyster Exotic dark colors, and baroque shapes. $500 to $25,000 and above
Freshwater Freshwater mollusc, which can carry up to about 50 pearls at once A vast range of shapes, sizes and colors. Round ones look almost identical to Akoya at a lower price. $50 to $2,000

Saltwater pearls nucleate for two to three years, one pearl per oyster, which is what builds thicker nacre and more even luster. That time is also why they cost more.

The Tahitian nacre rule you have probably read is out of date. From 1998, French Polynesia required every exported Tahitian pearl to be X rayed and certified to at least 0.8mm of nacre per side, over 80 percent of the surface, and pearls that failed were destroyed. That requirement was scrapped in January 2017. All pearls may now be exported and are taxed regardless of quality, which is why few poor ones travel. Most pearl sites still print the rule as though it were current. It is worth knowing as a durability benchmark, roughly 1.0mm being a healthy depth, and not as a guarantee that anything on the market has passed a test.

Surface characteristics, and the three that are not flaws

Anything with organic origins carries imperfection. Most surface marks are cosmetic and lower the grade. Some are growth characteristics that do not, and one of them is evidence of quality.

CharacteristicWhat it isLowers the grade
WrinklesUneven nacre formation. Expected, and often desirable, on pearls nucleated to be non round.Yes, on round pearls
SpotsSlight variations of color.Yes
AbrasionsScratches or scuffs that interrupt the luster.Yes
Dents and divotsIndentations in the nacre, varying in size.Yes
MottlingA light plating pattern formed inside the oyster.No. It indicates a thick nacre layer.
Kobs and tipsGrowth characteristics.No, unless chipped, which affects durability.
CirclesA growth characteristic that gives a distinctive banded look.No.

How rare a fine pearl actually is

StageShare
Nucleated oysters that survive to bear a pearlAbout 50 percent
Of those, pearls that are marketableAbout 20 percent
Nucleated oysters yielding fine gem qualityFewer than 5 percent
The grade above AAAHanadama, certified by the Pearl Science Laboratory in Tokyo

These are figures the trade repeats rather than peer reviewed research, and pearl grading itself is not standardized, so treat every tier on every chart as one seller's opinion until you have looked at the pearl.

From the bench · Andrea Li

What a strand costs before it reaches a store

Every pearl chart online is written from the selling side. This is the buying side, from the trays at the Tucson gem shows.

Where I was buyingPrice per strand
Lower tier shows, early onUnder $20, freshwater
Gated shows, as my eye improvedRoughly $100 to $600
My vendor now, at the AGTA showLow hundreds into the low thousands

Ranges, not invoices. The point is the distance between the tiers, which is close to two orders of magnitude for something a chart would call the same product.

Where I stop matters as much as where I start, and the metal is what decides it. My work is demi fine: sterling silver, gold filled, gold vermeil, and solid 14k gold on occasion. Fine jewelry is solid 18k or 24k gold and platinum, and those metals are what carry a very expensive stone. A single pearl at several hundred to several thousand dollars belongs in a setting built to hold it for a lifetime, which is a different piece from the one I am making. So my ceiling is deliberate, not a budget. Grading charts show you every tier as though a buyer should climb to the top of it, and none of them tells you which tier suits the work in front of you.

Pearls are sold in bundles the trade calls bead lots. I have always called them shanks. A shank holds roughly 25 to 50 strands of small 2mm pearls, or around 15 strands at 10 to 11mm. I go through every strand in a shank before I choose one, looking for brilliance of luster, uniform shape, and consistent iridescence. What I will not buy is thin nacre: chalky patches, dull spots, irregular shapes and sizes.

The shows run in tiers, and the tier tells you what you are looking at. At the open end, vendors convert motel rooms into showrooms, free and no registration. Above that, tented shows you register for. At the top, the AGTA GemFair, indoors at the Tucson Convention Center. AGTA vets its buyers as well as its vendors: to get in I had to produce receipts proving my business had spent at least $10,000 in the previous year, along with my business license, cards and packaging. Once quality has been filtered that far upstream, the only thing left deciding what reaches my tray is taste.

One thing no chart will tell you. Pearls are less brittle than gemstones when you drill them, and more fragile than gemstones once they are set. A pearl is aragonite platelets bound by conchiolin, built like structural plywood rather than a rigid crystal, so a bit passes through without the stress that chips a briolette at its narrowest point. That same softness is why a finished pearl needs protecting in a way a sapphire never does.

 
 

From the bench · Andrea Li

The give that keeps them whole

A note from Andrea Li, who sets both pearl and moonstone by hand in her Denver studio.

On the back of my work there is a weave, a web of wire I was told for years to hide and never could. It is the truest part of what I make. Every strand is held under tension, and the whole thing holds precisely because each one gives a little instead of snapping. Setting a pearl beside a moonstone taught me that lesson twice over.

Strength was never rigidity. It is knowing where to give.

A pearl is soft, Mohs two and a half, built of thousands of aragonite platelets bound in a protein called conchiolin, closer to structural plywood than a rigid crystal. That give is its whole gift. Across thousands of pearls, not one has ever broken on me, because when I widen a hole and seat the pearl on a peg it flexes and absorbs the pressure instead of fracturing. A hard, brittle gem does the opposite, cleaving along a hidden plane the moment you ask too much of it.

Moonstone teaches the same truth from the other side. It looks soft and lit from within, yet it is brittle, so I have to give on its behalf, working slow and cool. Even its glow is a kind of give: that blue drift, called adularescence, is only light slipping between microscopic layers inside the stone. Rigid things shatter. The ones that yield, a little, in the right place, are the ones that last. That is the throughline held in the weave on the back of every piece I make: pressure met with give, and turned into something more beautiful for it.

 

From the bench · Andrea Li

The tells I use to know them apart in a second

A note from Andrea Li, who sets both stones by hand in her Denver studio.

After years of setting both, I do not have to think about it anymore. These are the four things I read, side by side.

PearlMoonstone
Where the light livesOn the surface: a satiny lustre, sometimes a faint rainbow orient drifting over itInside: a blue-white glow that floats and moves as you tilt the stone (adularescence)
Light through itOpaque, no light passes throughTranslucent, light passes in and scatters
What it isOrganic, made by a mollusk in layers of nacreA mineral, a feldspar formed in the earth
How it behaves at my benchSoft but forgiving. A pearl has never broken on me.Harder, but brittle. It can cleave at the drill hole if it is stressed.

That last line is the one no chart will tell you. A pearl rates only 2.5 to 3 for hardness, far softer than moonstone, yet its organic, layered structure absorbs stress instead of fracturing. Moonstone is harder, but it has cleavage planes, and a hard knock or too much tension where the hole is drilled will split it clean. Softer is not always more fragile.

 

Frequently asked questions

Is moonstone the same as a pearl?
No. A pearl is organic, made by a mollusk, and opaque. A moonstone is a mineral in the feldspar family, formed in the earth, and translucent. They can look similar because both have a soft inner-seeming glow, but the glow works in completely different ways.
How can I tell a pearl from a moonstone quickly?
Tilt it toward the light. If the glow stays put on the surface as a soft sheen, it is a pearl. If a blue-white light floats and drifts across the stone as you move it, it is a moonstone. Pearls are also opaque, while moonstone lets light pass through.
What is the rainbow shimmer on a pearl called?
That is called orient. It is the faint, iridescent rainbow play that seems to dance on or just beneath a pearl's surface, separate from its basic surface sheen, which is called lustre.
What is the floating blue light in a moonstone called?
Adularescence. It is caused by light scattering between microscopically thin layers inside the stone, which makes the glow appear to hover just below the surface and drift as the stone is tilted.
Are pearl and moonstone both June birthstones?
Yes. June has more than one birthstone, and both pearl and moonstone are among them, along with alexandrite. So either stone is a fitting choice for a June birthday.
Which is more durable, pearl or moonstone?
Moonstone is harder on the Mohs scale (about 6 to 6.5) than a pearl (about 2.5 to 4.5), so it resists scratching better. But moonstone is brittle and can chip or cleave from a sharp knock, while a pearl's main enemies are scratches, acids, heat, and chemicals. Both are best treated gently.
How do you clean pearl and moonstone jewelry?
Skip the ultrasonic cleaner and skip heat. Neither stone tolerates them. The safest method for both is warm water, a soft toothbrush, and a drop of Dawn dish soap to remove the oils and dust that dull a piece, then a soft polishing cloth to bring the metal back. Put pearls on last and take them off first so they never meet perfume, lotion, or hairspray.

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