The crystal market has a real problem. Supply chains are murky, labeling is inconsistent, and the global demand surge of the last decade created a gold rush for counterfeiters. Walk any wholesale district and you’ll see clear glass beads packaged as “natural amethyst,” green bottle glass labeled “moldavite,” and pale chalky howlite dyed turquoise-blue sitting under a sign that says genuine turquoise, ethically sourced.

Not every seller is dishonest. Many shop owners genuinely don’t know what they’re selling. They bought from a wholesale supplier who bought from a distributor who bought from a factory, and the provenance documentation got thinner at every step. The fraud is often structural, not personal.

This guide covers every reliable authenticity test, from the free checks you can do in thirty seconds to the scientific tools that produce near-definitive answers. It also goes stone-by-stone through the minerals that get faked most aggressively, because a generic checklist won’t catch a fake that’s been specifically designed to pass generic checklists.

I carry a small bottle of acetone and a cotton swab to Tucson every single year. It takes thirty seconds, costs nothing, and catches the majority of dyed fakes at a show table before I’ve committed to a single dollar. That habit has saved me more money than I want to calculate, including the $62 Sleeping Beauty turquoise cabochon I walked away with in 2023 after the test confirmed zero dye transfer on three different pieces at the same booth.

Understanding What “Fake” Actually Means

“Fake crystal” isn’t one category. It’s four distinct problems, and conflating them leads to bad purchasing decisions and worse conversations with sellers.

1. Glass or resin passing as a mineral.

The most common outright counterfeiting. Clear glass beads as “natural quartz,” green bottle glass as moldavite, rose-tinted resin labeled “rose quartz sphere.”

2. Misidentification: a real mineral under the wrong name.

Sodalite is sold as lapis lazuli. Serpentine is sold as jade. Copal is sold as amber. The stone is real; the label is wrong. Sometimes the seller is deceiving you. Sometimes they genuinely don’t know.

3. Treated or enhanced stones sold without disclosure.

Heat treatment, dyeing, surface coating, resin stabilization: all of these change a stone’s appearance. The mineral underneath may be genuine, but the color you’re buying was manufactured in a kiln or a chemical bath. Full disclosure is the ethical standard. Silence is the common practice.

4. Lab-grown crystals sold as natural.

Lab-grown amethyst, synthetic quartz, hydrothermal emerald: chemically identical to natural material, formed in weeks inside a reactor rather than over millions of years on Earth. Some buyers don’t care about the distinction. Others care deeply. Either way, they deserve to know.

Knowing which category you’re dealing with changes which tests you run. Glass fakes fail physical tests. Misidentified minerals often pass physical tests but fail mineral-specific identification. Treated stones may pass almost every physical test and require chemical analysis or expert eyes. Lab-grown material is virtually impossible to detect without advanced equipment.

The Five Free Tests: No Equipment Needed

These require nothing but your hands, a window, and five minutes. They catch glass fakes and low-effort resin imitations reliably. They do not catch sophisticated misidentification or high-quality synthetic material.

Temperature: The First Thing You Check

Real minerals are cold. Genuinely, noticeably cold, not room-temperature-against-skin, but cool in a specific way you recognize once you’ve held enough genuine material.

The reason is thermal conductivity. Quartz conducts heat away from your skin at approximately 7.7 W/m·K. Common soda-lime glass conducts at roughly 1.0 W/m·K, about one-eighth the rate.

In simple terms, when you press genuine quartz to your wrist, heat transfers away from your skin rapidly, which registers as sustained coldness. Glass transfers heat much more slowly, so it feels like it warms faster. This isn’t intuition. It’s a measurable material property. (Engineering Toolbox: Thermal Conductivity of Common Materials)

Press the stone to the inside of your wrist, not your palm. Your palm is warm and calloused; the inner wrist reads temperature more accurately. A genuine quartz, amethyst, or tourmaline will feel distinctly cool. Hold it there for thirty seconds. Genuine mineral holds that coolness longer than glass does, and dramatically longer than plastic or resin.

At the Denver show in 2020 I picked up a deep purple fluorite octahedron from a Chinese dealer’s table. What I remember most is how cold it felt, not room-temperature cold the way quartz feels, but genuinely cold and glassy, heavier than you’d expect from something that transparent. That combination (colder and heavier than expected) is a physical signature that’s hard to fake convincingly in resin.

Weight: Density Doesn’t Lie

Pick up the stone. Estimate what it should weigh for its size. Now consider again: does it feel heavier than that estimate, lighter, or about right?

Real minerals have specific gravity, a fixed ratio of mass to volume, that varies predictably by mineral species. Quartz is 2.65. Hematite is 5.26. Glass fakes often feel lighter than the mineral they’re imitating because manufacturers rarely match density precisely, and resin is notably lighter than most minerals.

In July 2018 a fellow practitioner named Sarah handed me a tumbled hematite across a coffee table in Boulder and said: “You don’t need more heart healing right now. You need to come back into your body.” I nearly dropped it. Smaller than a matchbox and it wanted to fall through my palm. That’s specific gravity 5.26, almost twice as dense as quartz at 2.65. Holding a glass piece the same size would feel like holding air by comparison. Density doesn’t lie, and it can’t be faked without using the correct material.

The Bubble Check

Hold the stone up to a strong light (phone flashlight or direct sunlight). Look through it to see if it has any transparency. Look for spherical air bubbles.

Real minerals can contain inclusions (other minerals, fluid pockets, natural fractures), but these look completely different from the spherical bubbles trapped when liquid resin or glass cools in a mold. Genuine inclusions are irregular, angular, mineral-colored, sometimes wispy or fingerprint-shaped. Fake bubbles are round, uniform, often oriented in patterns that follow the pour direction.

One genuine exception: enhydro quartz. These rare specimens contain actual water trapped during crystal formation. The bubble moves when you tilt the stone. If your “bubble” moves, you may have something far more interesting than a fake. Check before you dismiss.

The Imperfection Check

Real minerals are imperfect. Not always obviously. But always. They show color zoning, inclusions, slight transparency variations, surface irregularities, and growth patterns that reflect the specific conditions of their formation.

Fakes are often too perfect. Too uniform in color. Too smooth across the surface. Too symmetrical for a “natural” specimen. If you’re looking at a crystal point that looks as though it was computer-designed, it was designed by a mold.

A magnifying glass helps here. Genuine minerals show micro-inclusions, slight pitting, growth lines, and cleavage traces that vary across the surface. Resin fakes show a homogeneous texture that looks the same under magnification as it does to the naked eye.

The Text Test

Place the stone flat over printed text. On a genuine crystal (especially quartz), you’ll see the text distorted, bent in different directions, sometimes doubled. This happens because natural crystal has internal structure that refracts light simultaneously in multiple directions.

Glass behaves differently. Glass magnifies text without distorting it into multiples. Compare a piece of clear quartz to a wine glass over the same page. The quartz scatters; the glass magnifies cleanly.

This test works best on clear quartz, citrine, amethyst, and any transparent mineral. It’s useless on opaque stones.

The Acetone Test: The Most Underused Field Skill

This is the test I use at every gem show, and it’s the one almost no beginner crystal guide covers. The concept: dye bleeds. Mineral color doesn’t.

1. Get a cotton swab and a small bottle of acetone (nail polish remover).
2. Wet the tip of the swab with acetone and rub it firmly against an inconspicuous spot on the stone: the back, a rough patch, the area near the drill hole on a bead.

If color transfers to the swab: the stone is dyed.

Natural mineral color is structural. The iron oxide that makes carnelian orange is part of the mineral lattice and it won’t rub off on a swab no matter how hard you scrub. The copper compounds that give malachite its green are woven into the crystal chemistry. They don’t move.

Artificial dye is a surface treatment. It pools in the porous microstructure of the stone and releases when it meets a solvent.

Turquoise Testing With Acetone:

This is the single most useful field test for anyone buying at shows.

Damp swab on the surface: if blue transfers to the cotton, it’s dyed howlite. If nothing transfers, it’s at minimum genuine turquoise. I ask to test an inconspicuous spot on any piece of turquoise priced under $15 before I consider anything else.

Carnelian Testing With Acetone:

Natural and heat-treated carnelian both get their color from iron oxide within the mineral. Zero color transfer. Dyed agate bleeds immediately. This matters because much of what’s sold as “deep red carnelian” is agate dyed with iron oxide solution and baked, passable visually, but the color sits on the surface rather than being part of the stone’s internal structure.

Lapis lazuli Testing With Acetone:

Lower-grade lapis lazuli is frequently dyed more deeply saturated. Real lapis color doesn’t transfer. Dyed material leaves blue on the swab.

Critical Limitation of the Acetone Test

The acetone test only catches traditional dye. It does not reliably catch modern polymer or acrylic dye treatments, which are increasingly common and resist acetone. A negative test result (no color transfer) reduces the probability of dye treatment but does not confirm the stone is undyed. This is not a failure of the test; it’s a limitation you need to know. For high-value pieces, a negative acetone test is a good sign, not a green light.

The Specific Gravity Method: The Most Reliable At-Home Test

This separates serious collectors from casual buyers. Almost no crystal blog covers it properly, and it’s the most genuinely diagnostic at-home test available.

Specific gravity is the ratio of a mineral’s mass to the mass of an equal volume of water. Every mineral species has a known specific gravity value. Glass fakes rarely match the specific gravity of the mineral they’re imitating.

This means you can perform a near-definitive identification test at home with a $30 digital scale and a bowl of water.

A Note on Scale Accuracy

Before you run this test, understand where the error comes from. A scale accurate to 0.1g sounds precise, but on a small stone it isn’t. If your stone weighs 10g dry and your scale has a ±0.1g variance, your dry weight could read anywhere from 9.9 to 10.1g. That 0.2g spread translates to a specific gravity error of roughly ±0.05 on a 10g stone, enough to blur the line between some mineral pairs that sit close together (hematite vs. hematine, for example).

The fix: use the largest stone you can reasonably test, and weigh it three times. Average the three readings. A 40–50g stone shrinks that error to negligible. Also calibrate your scale before each session with a known reference weight, since most kitchen scales drift. A ±0.1g error on a 50g stone produces an SG error of around ±0.01, which is within the precision range of most published mineral data. On a 10g stone, that same scale produces an error 5× larger.

Step-by-Step Method to Testing a Stones Specific Gravity

You need: A digital scale accurate to at least 0.1g, a container of water deep enough to fully submerge your stone, and a thin wire or straightened paper clip to suspend the stone.

Step 1: Weigh the dry stone and record it as Dry Weight (DW).

Step 2: Place the water-filled container on the scale and zero it (tare).

Step 3: Suspend the stone from the wire so it hangs completely submerged without touching the sides or bottom. Record this weight reading: the Wet Weight (WW). This is the displaced water weight.

Step 4: Divide DW by WW.

Specific Gravity = Dry Weight ÷ Wet Weight

Example: A suspected piece of quartz weighs 42g dry and the scale reads 16g when suspended in water. 42 ÷ 16 = 2.625, which matches quartz’s known specific gravity of 2.65. Almost certainly genuine quartz.

If your “quartz” comes back at 2.2 or 2.4, you have glass or resin.

If your “hematite” comes back at 3.1 instead of 5.26, it’s a manufactured fake.

Best Stones to USe the Specific Gravity Test For:

Jade:

Nephrite runs 2.90–3.02. Jadeite runs 3.25–3.36. Serpentine, the most common jade substitute, comes in at 2.44–2.62. You can distinguish all three with no other test.

Hematite vs. hematine:

Real hematite: 5.26. Hematine (a manufactured magnetic material often sold as hematite): approximately 4.9–5.1. Not as wide a gap as with jade, but measurable if your scale is accurate.

Turquoise:

Genuine turquoise: 2.60–2.85. Howlite: 2.45–2.58. Note that turquoise’s range is wide (varies with composition and stabilization), so SG alone isn’t definitive here. Pair it with the acetone test.

Moldavite:

Genuine Czech moldavite: 2.32–2.38. Lead glass fakes run heavier due to lead content. If your “moldavite” specific gravity comes back at 2.5 or above, that’s a flag.

Advanced Tools Worth Owning

For serious collectors, certain tools remove most uncertainty.

UV/Black Light ($15–$40)

Some minerals fluoresce under ultraviolet light; most glass fakes don’t. Take the stone into a darkened room and shine UV light on it.

What to look for:

• Calcite: Bright orange, pink, or red fluorescence
• Scheelite: Vivid blue-white
• Fluorite: Often blue or green (highly variable between specimens)
• Willemite: Intense green (looks electric)
• Selenite/gypsum: Pale blue-white
• Most glass: No fluorescence, or a weak uniform glow

Not conclusive alone: some genuine minerals don’t fluoresce and some glass formulations do. Still useful as part of a multi-test approach. The lapis lazuli UV test is particularly useful: genuine lapis often shows yellow-orange fluorescence patches from its calcite component. Synthetic substitutes rarely replicate this.

A Gemological Refractometer ($50–$150)

A refractometer measures a stone’s refractive index (RI), the precise angle at which it bends light. Every mineral species has a characteristic RI. Glass has a different RI from most natural minerals. This is the primary identification instrument used by professional gemologists, and entry-level versions are genuinely accurate.

Key reference points:

• Quartz (amethyst, citrine, rose quartz): RI 1.544–1.553
• Common soda-lime glass: RI approximately 1.51–1.52
• Peridot: RI 1.654–1.689 (birefringence 0.035)
• Spinel: RI 1.718
• Fluorite: RI 1.434

Full RI and physical property data for any mineral species is available via the GIA Gem Encyclopedia and Mindat.org, both free and authoritative.

The refractometer also measures birefringence, which is the difference between a mineral’s two refractive indices. Quartz has birefringence of 0.009. Iceland spar (optical calcite) has birefringence of 0.172, which is why it doubles text so dramatically when placed over a page. Glass has zero birefringence. This is a near-definitive glass vs. mineral test for transparent stones.

A Dichroscope ($30–$80)

A dichroscope reveals pleochroism, meaning whether a stone shows different colors when viewed from different angles under polarized light. Most natural colored minerals are pleochroic to some degree. Most glass is not. This is particularly powerful for distinguishing natural citrine from heat-treated amethyst.

The laptop screen citrine test (no equipment purchase required): Natural citrine is dichroic. Heat-treated amethyst is not. Hold the stone in front of your laptop screen at maximum brightness on a white background, which provides polarized light. Slowly rotate the stone. If you see the color shift as you turn it, it’s dichroic, consistent with natural citrine. If the color stays completely uniform through the rotation, it’s heat-treated material. A $0 test that provides a clean separation between the two.

Stone-by-Stone Authentication Guide

Generic tests catch generic fakes. The stones below get faked in specific ways that require specific knowledge.

Moldavite

The most aggressively counterfeited crystal on the market. Genuine moldavite is a tektite, natural glass formed approximately 14.7 million years ago when a meteorite impact in what is now the Czech Republic melted surrounding rock, ejecting it into the atmosphere where it cooled into this distinctive olive-green glass. An estimated 275 tons of authentic moldavite exist, spread across a narrow strewnfield in Bohemia, Moravia, and Lusatia.

At the peak of the moldavite craze, fakes were being mass-produced in China and Thailand. Most are green bottle glass melted and poured into molds.

Surface texture: Genuine raw moldavite has deeply sculpted, irregular topography: unique grooves, ridges, and dissolution pitting from 14 million years of weathering in soil. Each piece is distinct. Mold fakes show repeated patterns; the surface wrinkling appears in the same locations across multiple pieces from the same batch. If a seller has ten “moldavites” that look like siblings, they came from a mold.

Color: Genuine ranges from mossy to forest green to brownish-green. Rarely bright, rarely neon, with internal color variation when held to the light. Fakes often read as brighter, more saturated bottle-green.

Internal structure: Real moldavite contains irregular bubbles and lechatelierite inclusions (pure silica glass formed from melted quartz, appearing as wispy white or colorless threads). Fakes have cleaner interiors or uniform round bubbles typical of manufactured glass.

Chemical composition: Genuine moldavite from the South Bohemian strewnfield runs approximately 79–80% SiO₂ with trace amounts of iron, titanium, and zirconium. Analyzed fakes have shown high lead content, almost no iron or zirconium, and elevated potassium: a completely different chemical fingerprint. If you’re buying expensive raw moldavite, ask if the seller has XRF data. Some dealers at Tucson carry handheld XRF devices and will test on request.

Refractometer limitation: Don’t rely on refractive index for moldavite. Its RI (1.480–1.510) overlaps directly with common glass. Surface texture, inclusions, specific gravity (2.32–2.38), and chemical analysis are the reliable tests.

Price reality: Authentic Czech moldavite has sold for $15–$30+ per gram for quality raw material in recent years. A $5 “moldavite” is green glass.

Turquoise

One of the most commonly faked minerals in the world, for one simple reason: real turquoise is rare, high-quality real turquoise is rarer still, and dyed howlite looks almost identical to most buyers.

Natural turquoise is a hydrous phosphate of copper and aluminum. That copper content gives it the distinctive blue-green color. It forms in arid regions where copper-bearing groundwater percolates through rock over millions of years.

Dyed howlite is a calcium borosilicate, naturally white with gray-black veining. It absorbs dye exceptionally well. Under a blue dye bath, it produces something that looks convincingly turquoise.

Authentication:

• Acetone test: The fastest, most reliable field test. Genuine turquoise releases no color. Dyed howlite releases blue onto the swab within seconds. Caveat: polymer-sealed dyed stones may pass the acetone test, so a negative result reduces probability of dye treatment but doesn’t confirm authentic turquoise.
• Hardness: Turquoise sits at 5–6 Mohs. Howlite is softer at 3.5. A copper coin (hardness ~3) won’t scratch turquoise but will scratch howlite. Test inconspicuously.
• Matrix inspection: Genuine turquoise matrix has a three-dimensional quality: the dark veining sits within the stone. Dyed howlite matrix often looks flat and painted-on under magnification, with dye concentrating more heavily in the veins than in the body.
• Color variation: Real turquoise has subtle depth variation: slightly greener or bluer patches, occasional lighter areas. Dyed stones often have unnaturally uniform saturation.

I bought a genuine Sleeping Beauty cabochon at Tucson in January 2023: robin’s egg blue, minimal matrix, old stock from before the mine closed to turquoise production in 2012. The dealer asked $75; I paid $62 after a conversation about provenance. The quality I registered wasn’t primarily visual. It was what I can only describe as ceremonial weight, a seriousness that accumulates from five thousand years of being taken seriously by every civilization that encountered it. I’d waited almost eight years after first encountering turquoise’s history in ceremonial context before acquiring my own piece. That context doesn’t make it more or less authentic chemically, but it changes how you approach the decision.

Citrine

Here’s what almost nobody explains clearly: the majority of citrine on the market is heat-treated amethyst. This isn’t fraud. It’s industry standard. The problem is most sellers don’t mention it, which means you’re paying a premium you don’t realize you’re paying.

Natural citrine forms when quartz is heated geothermally within the Earth over geological time, producing a pale yellow to light champagne color. It’s uncommon. If your citrine is a $5 tumbled stone with an intense orange-yellow color, it isn’t natural citrine.

Heat-treated amethyst (commercial “citrine”): When amethyst is heated to approximately 470–560°C in a kiln (peer-reviewed research places optimal color development at around 500–560°C, with lighter fading occurring below 440°C, Dedushenko et al., 2004, “Iron Impurities in Quartz: An EPR and Optical Study,” Physics and Chemistry of Minerals) and the purple converts to yellow-orange. The resulting color tends to be more saturated, often with a reddish-orange at the crystal tips and lighter or white zones toward the base.

Visual tells for heat-treated material:

• Orange at the tip, whitening or bleaching toward the base, which is near-diagnostic of heat treatment
• The “dogtooth” crystal termination shape common to Brazilian amethyst geode material
• If it’s a geode with yellow-orange points inside, it was an amethyst geode that went in a kiln. Natural citrine does not form in geodes.

The dichroism test: Natural citrine is dichroic. Heat-treated amethyst is not. This test (described under Advanced Tools) is free, requires no equipment beyond your laptop, and provides a clean separation. It’s the best single test for this specific distinction.

The terminology issue: Much of what’s sold as “Madeira citrine,” “Spanish citrine,” or “premium amber citrine” is heat-treated amethyst with marketing language attached. None of those names indicate natural formation.

Amethyst

Most amethyst sold as “natural” genuinely is natural. But three specific fraud types are worth understanding:

Glass fakes: Deep purple glass passed off as amethyst, particularly in bead form. The glass fake shows no color zoning, spherical air bubbles, and RI around 1.51 vs. amethyst’s 1.544–1.553.

Dyed quartzite: Pale quartzite or agate dyed purple. Under magnification, dye concentrates in grain boundaries between microcrystalline quartz particles. You can see it pooled in the spaces between grains rather than distributed through a continuous crystal. Acetone test catches this.

Synthetic (lab-grown) amethyst: Chemically near-identical to natural. Differences: no loupe-visible inclusions, perfectly uniform color, absent color zoning (the lighter/darker purple bands following crystal growth pattern that characterizes natural material). No at-home test conclusively identifies lab-grown amethyst. Raman spectroscopy is the definitive tool. For practitioners: synthetic amethyst is not a glass fake. It’s real amethyst grown in a reactor. Whether that matters to your practice is a philosophical question.

Lapis Lazuli

Lapis is a rock composed of lazurite (the blue), calcite (white streaks), and pyrite (metallic gold flecks). That composition is both what makes it recognizable and what makes it easy to fake badly.

Common substitutes:

• Sodalite: Naturally blue, commonly confused with lapis. Tells: sodalite lacks pyrite inclusions, has a lighter more uniform blue, may show slight translucency at the edges. SG 2.14–2.40 vs. lapis 2.70–2.90: a measurable difference.
• Dyed howlite or magnesite: Both take dye well. The “pyrite” in these fakes is often metallic paint, visible under magnification as painted sparkle sitting on the surface rather than embedded metallic mineral.
• Enhanced lower-grade lapis: Real lapis that’s been dyed more deeply saturated and waxed to improve luster. Acetone test catches dye; a hot pin on an inconspicuous area produces a plastic or wax smell if filler is present.

UV test for lapis: Genuine lapis often shows yellow-orange fluorescence patches under UV light, from the calcite component. Most synthetic substitutes don’t replicate this response consistently.

Jade (Nephrite vs. Jadeite vs. Serpentine)

The jade category deserves separate treatment because the substitution hierarchy is complex and the price differences are enormous.

Jadeite: More valuable. Translucent, intense green, SG 3.25–3.36. Fine Imperial Jade commands prices comparable to fine emerald.

Nephrite: Traditional jade of China and New Zealand. Dense, waxy luster, SG 2.90–3.02. Less translucent than jadeite with a different textural quality.

Serpentine: The most common substitute. Soft, waxy green mineral, SG 2.44–2.62, hardness 3–4. A copper coin scratches serpentine but not nephrite. The specific gravity test separates all three definitively.

At Tucson in 2017 I bought a white Hetian nephrite pendant the dealer identified as genuine mutton fat nephrite, the most prized variety in Chinese tradition. I confirmed within about thirty seconds of handling: unmistakable weight and an oily warmth to the lustre that serpentine doesn’t replicate. Nine years of regular handling later, the lustre has deepened into what Chinese collectors call bao jiang, the patina that develops on nephrite from contact. No plastic or resin fake does that. The surface of genuine nephrite evolves with use, and that property alone distinguishes handled jade from everything else in the category.

Rose Quartz vs. Pink Glass

Pink glass passes for rose quartz more often than most buyers realize because rose quartz’s natural milkiness (from tiny rutile needle inclusions) can be visually approximated by frosted glass.

The tells: Rose quartz always occurs in massive form, with no natural crystal faces and no natural terminations. The crystal points you see in photos were cut into that shape from massive material, not grown that way. Genuine rose quartz has a specific soft internal milkiness from microscopic rutile inclusions distributed through the crystal lattice. Glass fakes have a more hollow-looking clarity, even when frosted.

Temperature holds more consistently in rose quartz than in glass. SG of rose quartz (2.65) matches common glass closely enough that density alone isn’t diagnostic here. Use the temperature test and the visual imperfection check together.

Amber

Amber is one of the most commonly faked organics on the market, and the fraud spectrum is wider than with minerals. You’re not just dealing with synthetic material, but with a completely different organic substance (copal) that is frequently mislabeled as amber. The price difference is significant and the visual difference is nearly invisible to an untrained eye.

What amber actually is: Fossilized tree resin, millions of years old. Baltic amber, the most traded variety, dates to approximately 44 million years ago. Copal is also fossilized tree resin, but young: typically under 1 million years old, sometimes just thousands. It looks identical. It behaves almost identically. It is worth a fraction of the price.

The salt water test is the most reliable free field test for amber: dissolve 2–3 tablespoons of salt in a glass of water. Genuine amber (SG 1.05–1.10) floats in saturated salt water. Copal floats too, so this test doesn’t separate amber from copal, but it will sink plastic (SG ~1.2–1.4) and most glass imitations. Any “amber” that sinks in strong salt water is neither amber nor copal.

The acetone test for copal vs. amber: Rub an acetone-dampened swab firmly on an inconspicuous surface for fifteen seconds. Genuine amber is fully polymerized and chemically inert, so the surface won’t soften or become tacky. Copal is incompletely polymerized and will soften noticeably under acetone, sometimes becoming sticky or leaving a smear on the swab. This is the most reliable separation test between the two.

Inclusions: Genuine Baltic amber frequently contains insect inclusions, plant matter, and air bubbles formed during the original resin flow. Fakes have perfectly preserved, centered, photogenic insects, because the insect was placed in liquid resin before it hardened in a mold. Real inclusions look chaotic. The insect is usually partly obscured, off-center, or trapped mid-motion in a way that doesn’t photograph well. If the insect inclusion looks like a museum display, it probably came from a factory.

UV fluorescence: Genuine Baltic amber typically fluoresces a distinctive blue-green under shortwave UV. Copal shows weaker or different fluorescence. Plastic shows little to none. Not definitive on its own, but consistent with other tests.

Price flag: Natural Baltic amber with authentic insect inclusions starts at $30–50 for small pieces and escalates sharply with clarity and species of inclusion. “Amber with insect” priced under $15–20 is copal with a farmed inclusion, or plastic with a molded one.

The Fake vs. Enhanced vs. Misidentified Distinction

Not all altered stones are frauds. This distinction matters for your purchasing decisions and for evaluating what you already own.

Genuine fraud:

Glass sold as natural amethyst. Green bottle glass sold as moldavite. Resin sold as amber.

Undisclosed treatment (ethically problematic):

Heat-treated amethyst sold as “natural citrine” without disclosure. Irradiated topaz sold without noting the treatment. Stabilized turquoise sold as natural without noting the resin consolidation.

Legitimate enhancement with disclosure:

Stabilized turquoise (real turquoise impregnated with clear resin to improve durability, widely accepted in the industry when disclosed). Disclosed heat treatment on sapphire or amethyst. Aura quartz (natural quartz bonded with precious metals via vacuum deposition, disclosed and understood by buyers who seek it out).

Aura quartz specifically:

Angel Aura, Aqua Aura, Titanium Rainbow Aura: made by bonding natural quartz with precious metals (gold, titanium, platinum) in a vacuum deposition chamber. The iridescent surface is artificial. The quartz underneath is genuine. This is not fraud when disclosed. The fraud version is sprayed acrylic or painted imitation aura quartz. This coating chips and peels, while genuine aura bonding is permanent.

How to Evaluate a Seller Before You Buy

The tests above work after you have a stone in hand. Source evaluation works before you spend anything.

1. Ask about provenance. A seller worth buying from can tell you at minimum the country of origin, ideally the specific mine or region. “Somewhere in Asia” is not an answer. “From our wholesale supplier” without any upstream documentation is a flag.
2. Notice the quantity of rare stones. Genuine rare crystals are rare. If a shop has forty “moldavites” priced at $12 each in a bin, they aren’t genuine. If a seller has hundreds of identical “natural crystals,” some came from a mold.
3. Ask about treatments directly. The question itself tells you something. Ethical sellers discuss treatments proactively because they know it matters to buyers. Defensive or evasive responses to direct treatment questions are reliable signals.
4. Look at the labeling language. “Natural,” “genuine,” and “authentic” on a label mean nothing legally. What matters is how the seller responds when you ask specific questions. A seller confident in their product welcomes questions.

Price reality checks by stone:

Counterfeit Certificates: The Fraud Nobody Warns You About

Gem show reporting and collector community discussions increasingly flag counterfeit laboratory certificates as a significant and growing problem. A piece of paper saying “Certificate of Authenticity” from an unnamed or unfamiliar lab means essentially nothing.

How to verify a real certificate: Every major gemological laboratory maintains a publicly searchable online database of every certificate they issue. Each certificate has a unique identification number. Before trusting any certificate attached to a high-value purchase, go directly to the issuing lab’s official website and search the certificate number yourself. If the certificate number doesn’t appear in the lab’s database, the document is fake.

Lab-specific guidance for colored stones:

Different labs have built different specialties, and for ruby, sapphire, and emerald specifically, lab choice matters as much as having a certificate at all.

• GIA (Gemological Institute of America): The most recognized lab globally, strong for diamonds and widely trusted for colored stones. Their online Report Check at gia.edu/report-check accepts certificate numbers directly. For colored stones, GIA reports disclose treatment (heating, fracture filling) but don’t provide the detailed origin and treatment narrative that specialist labs do.
• AGL (American Gemological Laboratories): Considered the gold standard in the U.S. for ruby, sapphire, and emerald origin and treatment reports. AGL’s reports provide detailed geographic origin determination and treatment classification that go beyond most other labs. For high-value colored stones bought in North America, AGL is the lab name to look for.
• Gübelin Gem Lab: Swiss, founded 1923, considered the definitive authority for Burmese ruby and Kashmir sapphire origin determination. A Gübelin report on a significant colored stone is the closest thing to a blue-chip endorsement the trade produces. Certificate verification available directly on their site.
• SSEF (Swiss Gemmological Institute): Another leading Swiss lab with particular strength in natural pearl, colored sapphire, and padparadscha sapphire classification. For high-value natural pearls or premium sapphires, SSEF reports carry real weight among serious dealers. Verify at ssef.ch.

For any colored stone valued above $500 where natural origin and treatment status affect the price, the certificate should come from one of these four labs, not from an unfamiliar name or the selling dealer. Verify the certificate number directly before the transaction completes.

Red flags on certificates:

• Lab name you can’t independently verify online
• No certificate number (or a number that can’t be validated)
• Certificate issued by the seller rather than an independent lab
• Low-resolution printing or visible copy artifacts
• Certificates from online resellers that reference labs you can’t find

For pieces valued under a few hundred dollars, this level of verification may not be necessary. For anything significant (large moldavite pieces, fine jade, collector-grade material), verify the certificate number directly on the lab’s website before the transaction completes.

When to Get a Professional Opinion

Some things can’t be confirmed at home. Know when you’ve reached the ceiling.

A GIA-credentialed gemologist can identify most common fakes definitively using a loupe, refractometer, and polariscope. This costs nothing if you’re buying from a shop that employs one, or a small consultation fee at a gem show. Worth it for anything over $100 where authenticity matters.

Raman spectroscopy is the gold standard for identifying lab-grown vs. natural material, distinguishing treatment types, and confirming species identification. Commercial gem labs (GIA, AGL) offer this as a paid service. University geology departments sometimes have access. For high-value purchases where lab-grown vs. natural distinction matters, this is the appropriate level of testing.

XRF (X-Ray Fluorescence) analysis is how moldavite fakes are definitively identified by comparing silicon, iron, titanium, and zirconium content against known authentic samples. Handheld XRF devices are available at many large gem shows. Ask if the seller will let you run one on a suspect piece.

Quick Reference: Mohs Hardness + Specific Gravity

All mineral data verified against Mindat.org, the primary mineralogical reference database.

Closing Thoughts

The fake crystal problem is a supply chain problem wearing the mask of a knowledge problem. Most buyers who get sold a fake weren’t fooled because they lacked knowledge. They were fooled because they trusted a label that nobody upstream had verified.

The tests in this guide don’t require a geology degree. They require a cotton swab, a digital scale, a bowl of water, and the habit of asking questions before committing money. The temperature check takes ten seconds. The acetone test takes thirty. The specific gravity measurement takes five minutes and is near-definitive for most fakes.

More than any individual test, what actually protects you is building relationships with sellers who know their supply chain. The dealers I return to at Tucson and Denver year after year share one quality: they discuss provenance and treatments without being asked, because they know what they’re selling and where it came from. That transparency isn’t incidental. It’s the result of actually having documentation.

After twelve years of building a personal collection and working with clients, the mineral that most consistently surprises new collectors is hematite, specifically because the manufactured magnetic version (hematine) is so ubiquitous in retail that many people have never held a real piece. The weight is startling. That shock of unexpected density, that feeling of the stone pulling toward the ground: that’s what genuine material feels like. Once you’ve experienced it across enough different minerals, you develop a physical calibration for authenticity that no amount of reading about specific gravity can fully replicate.

Buy slowly. Ask questions. Run the tests. And when something feels wrong, that matters too.

Frequently Asked Questions