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TL;DR — Four different things get called "fake": synthetic (same chemistry, grown in a lab), treated (natural stone altered by heat, dye, glass filling or oil), imitation (glass or plastic that only looks like the gem), and substitution (a cheaper real gem sold under a costlier name). They need different tests. The nine Navratna gems belong to seven different mineral families with hardnesses from 2.5 to 10, so there is no single test — but a 10x loupe answers a surprising amount, because natural inclusions look nothing like gas bubbles and curved growth lines. The decisive answer is a report from a named gemmological laboratory, which identifies species and treatment and nothing else. Below: what each of the nine actually is, what it is faked with, the home checks that work, the ones that are folklore, and why a cheap Navratna ring cannot contain nine natural stones.
Navratna is where gemstone fraud concentrates, and the reason is structural. A Navratna piece asks for nine different gems at once, in small sizes, set together — and setting hides the girdle, the pavilion and most of the interior, which is exactly where the evidence lives. Four of the nine (ruby, emerald, blue sapphire, diamond) are among the most expensive materials on earth by weight. So a ring priced at a few thousand rupees is not a bargain on nine natural stones; it is a different product being sold under the Navratna name. This guide separates the four kinds of "fake", goes gem by gem, and is direct about which home tests are useful and which are folklore. For what a Navratna set is meant to contain and how the stones are traditionally arranged, see our Navratna nine gems guide.
Four different things people mean by "fake"
Getting this vocabulary right is most of the battle, because a seller can answer "yes, it is real" honestly about three of these four categories.
| Category | What it means | Is the seller lying? | How it is caught |
|---|---|---|---|
| Natural | Formed in the earth. May still carry routine treatment, which should be stated. | — | Inclusion character, laboratory report |
| Synthetic (lab-grown) | The same mineral with the same chemistry and crystal structure, grown in a factory. A synthetic ruby is corundum. It is not an imitation. | Only if it is sold as natural. Sold as synthetic, it is an honest product. | Curved growth striae and spherical gas bubbles in flame-fusion material; chevron growth and flux residue in hydrothermal material. Laboratory report for certainty. |
| Treated | A natural stone altered to improve appearance: heat, irradiation, dye, oil, resin or glass filling. | Only if undisclosed. Some treatments are near-universal and accepted; others are severe and change what you are buying. | Flash effect and bubbles at fractures for glass filling; dye concentrated in cracks; a laboratory report names the treatment. |
| Imitation | Glass, plastic, doublets, or a wholly different material made to look like the gem. | Yes, if sold as the gem. | Gas bubbles, swirl lines, mould seams, rounded facet edges, wrong hardness, wrong weight, warm to the touch. |
| Substitution | A cheaper real gemstone sold under a costlier name — quartz for topaz, spinel for ruby, glass-filled corundum for ruby. | Yes. | Refractive index, specific gravity, inclusion character. This is the category home tests handle worst. |
Tradition prescribes natural stones for the Navratna, and that preference is a matter of custom and belief rather than something a laboratory can adjudicate. The reasons to insist on natural material that are testable are simpler and worth stating plainly: you are paying a natural-stone price, and a synthetic or an imitation is worth a small fraction of it.
What the nine gems actually are
The nine belong to seven different mineral families, which is why no single test covers them.
| Gem | Material | Mohs hardness | Specific gravity |
|---|---|---|---|
| Ruby (Manik) | Corundum, aluminium oxide coloured by chromium | 9 | ~4.00 |
| Pearl (Moti) | Nacre — aragonite platelets in a conchiolin binder, formed by a mollusc | 2.5 to 4.5 | ~2.7 |
| Red coral (Moonga) | Calcium carbonate skeleton of a marine coral, Corallium | 3 to 4 | ~2.65 |
| Emerald (Panna) | Beryl coloured by chromium or vanadium | 7.5 to 8 | ~2.72 |
| Yellow sapphire (Pukhraj) | Corundum | 9 | ~4.00 |
| Diamond (Heera) | Carbon | 10 | 3.52 |
| Blue sapphire (Neelam) | Corundum coloured by iron and titanium | 9 | ~4.00 |
| Hessonite (Gomed) | Grossular garnet | 7 to 7.5 | ~3.65 |
| Cat's eye (Lehsunia) | Chrysoberyl, showing chatoyancy from fine parallel inclusions | 8.5 | ~3.73 |
Notice the spread. Diamond at 10 and pearl at 2.5 sit at opposite ends of the hardness scale; specific gravity ranges from 2.65 to 4.0. That variety is why a generic "gemstone test" does not exist, and why anyone offering one has not thought about it.
What the fakes are actually made of, gem by gem
Ruby, blue sapphire and yellow sapphire
All three are corundum, so they share a fake list. The dominant imitation is flame-fusion synthetic corundum, which has been manufactured industrially for over a century, is genuinely inexpensive, and is chemically identical to natural corundum. Under 10x magnification it typically shows curved colour banding and small spherical gas bubbles — nature does not make curves in corundum growth, only straight, angular, hexagonal zoning. The second problem, and increasingly the bigger one, is lead-glass-filled ruby: heavily fractured low-grade corundum impregnated with high-lead glass so it looks clean and red. It is real corundum by weight but structurally compromised; it is damaged by lemon juice, by ultrasonic cleaners and by a jeweller's torch. Under magnification the fractures show a distinctive blue or orange flash and trapped bubbles. Third: glass, plain and cheap, and red spinel or garnet sold as ruby. Fourth, and near-universal on natural material: heat treatment, which is generally accepted in the trade but should still be stated.
Emerald (Panna)
Natural emerald almost always contains inclusions — the French trade calls the pattern jardin, a garden. A flawless, glassy, cheap green stone is therefore a warning, not a bargain. The fakes are green glass (bubbles, swirl, rounded facet edges), synthetic hydrothermal and flux-grown emerald (real beryl, distinguishable by chevron growth patterns and flux residue), soudé doublets (two colourless halves cemented with green adhesive — immerse the stone in water and look from the side, and the colour resolves to a line at the join), and green quartz, peridot or tourmaline sold as emerald. Separately, almost all emerald is oil- or resin-filled to reduce the visibility of fractures. Minor filling is standard practice; significant filling materially changes value and must be disclosed.
Pearl (Moti)
The honest point first, because it is rarely made: almost every pearl sold today is cultured — grown in a mollusc after human intervention. That is not fraud, it is the market, and cultured pearls are real nacre. Genuinely natural pearls, formed without intervention, are extraordinarily rare and priced accordingly. A seller offering "natural pearls" at accessible prices is either using the word loosely or misrepresenting. The imitations are glass or plastic beads coated with pearl essence, and they are easy to catch: the coating flakes at the drill hole, the surface is perfectly smooth, and rubbing two against each other, or against the edge of a tooth, feels slippery where real nacre feels faintly gritty.
Red coral (Moonga)
This is one of the most heavily substituted materials in the Indian market. The fakes are dyed bamboo coral (a different, cheaper coral — look for concentric growth rings and dye concentrated in cracks and pores), dyed sponge coral (visibly porous), reconstituted coral (coral powder in a binder), dyed howlite or magnesite, glass, and plastic. Genuine Corallium shows fine parallel striations along its length and a wavy radial structure at a cut end. A cotton swab with acetone or nail-polish remover, wiped on an inconspicuous spot, will lift colour from dyed material and leave genuine coral unchanged. Note also that trade in several coral species is internationally regulated, so provenance is a fair question.
Cat's eye (Lehsunia)
The single most faked stone of the nine, and the fake is specific: fibre-optic glass. It is a manufactured bundle of fine glass fibres, cut so that the fibre ends produce a bright chatoyant band. It is very convincing to the naked eye and very obvious under a loupe, because the eye is unnaturally sharp, straight and chalky white, and the flat back of the cabochon shows a honeycomb of hexagonal fibre ends. Genuine chrysoberyl cat's eye has a softer, silkier eye that opens and closes as the stone is rocked, and good specimens show the milk and honey effect — one side of the eye lighter, one darker, under a single light. The other substitutions are quartz cat's eye and sillimanite, both real stones sold under the wrong name.
Hessonite (Gomed)
Faked with brown or orange glass, and substituted with lower-grade or different garnets and with heat-treated quartz. Natural hessonite characteristically shows a swirled, treacly internal texture under magnification, often described as a heat-wave or roiled effect, which glass does not reproduce.
Diamond (Heera)
Substituted with cubic zirconia (much denser — a CZ of the same dimensions weighs substantially more — and lacking diamond's crispness of facet edges), moissanite (doubly refractive, so under a loupe through the table you can see the back facet edges doubled), white sapphire, white topaz and glass. Separately, lab-grown diamond is real diamond and is now a large market; it is an honest product when disclosed and worth a fraction of natural when it is not.
Tests that actually work
1. A 10x loupe, used on the inclusions
If you buy one tool, buy this. What you are reading is not "clean versus included" but the character of what is inside.
- Natural stones show crystals of other minerals, healed fractures that look like fingerprints, fine needles, colour zoning in straight or angular lines, and two-phase inclusions — a liquid-filled cavity with a bubble inside it.
- Flame-fusion synthetic shows curved colour banding and free spherical gas bubbles.
- Glass shows round or elongated bubbles, swirl and flow lines, rounded and slightly soft facet edges, and often a mould seam.
- Glass-filled corundum shows a blue or orange flash along fracture planes as the stone is tilted, and flattened bubbles inside the fillings.
The distinction that trips people up: a bubble inside a liquid inclusion is a natural feature. A free bubble sitting in solid material is not. Learn that one difference and you will catch most glass.
2. Weight against size
Specific gravity is a fixed property, so a stone of known dimensions has a predictable weight. Cubic zirconia at about 5.7 weighs far more than diamond at 3.52 for the same measurements. Glass at around 2.5 weighs far less than corundum at 4.0. If a jeweller measures a stone with a gauge and weighs it, the two numbers together are close to diagnostic. This is a shop test rather than a home test, but it costs nothing to ask for.
3. Hardness, on the girdle only, and rarely
Hardness is informative because it is so unevenly distributed among these nine. Corundum at 9 and chrysoberyl at 8.5 are effectively unscratchable by anything in a household. Glass at about 5.5 is not. But this is a destructive test on a valuable object and it must be done, if at all, on the girdle where a setting will cover it — and never on pearl or coral, which are soft and will simply be damaged.
4. The pearl tooth test
One of the very few home tests that genuinely works. Rub the pearl gently against the biting edge of a front tooth. Real nacre, being built of overlapping aragonite platelets, feels faintly gritty or sandy. A coated glass or plastic bead feels glassy-smooth. Rubbing two pearls together gives the same information without involving your teeth. Then look at the drill hole with a loupe: on an imitation, the coating chips and shows a different material underneath.
5. The acetone swab for dyed coral and dyed stones
A cotton bud dampened with acetone or nail-polish remover, wiped firmly on an inconspicuous area, lifts colour from dyed coral, dyed howlite and dyed quartz. Genuine coloured material is unaffected. Do this before the stone is set, and on the base if it is a cabochon.
6. Immersion, for doublets
Put a suspect emerald in a glass of water and look at it from the side rather than from the top. A soudé doublet — two pale halves cemented with coloured adhesive — gives itself away as a concentrated line of colour at the join, because immersion cuts the surface reflections that normally hide it.
7. The instruments a jeweller has, and what each one settles
- Refractometer. Measures refractive index, which is diagnostic for most species. Corundum reads about 1.76 to 1.77; beryl about 1.58; glass usually well below.
- Polariscope. Separates singly refractive materials (glass, cubic zirconia, garnet, diamond) from doubly refractive ones (corundum, beryl, chrysoberyl). If a "sapphire" reads singly refractive it is not corundum.
- Dichroscope. Shows pleochroism — different colours along different crystal directions. Corundum and beryl show it; glass never does.
- Hydrostatic balance. Measures specific gravity directly.
- Thermal and electrical probes. Separate diamond, moissanite and their imitations.
None of these takes more than a minute, and a jeweller who declines to put a stone on a refractometer in front of you has answered the question.
Tests that do not work, and why
The fog or breath test for diamond
The claim is that a real diamond clears instantly because it conducts heat. Diamond does conduct heat exceptionally well — but so does moissanite, which is the imitation you are most likely to meet, and the result depends heavily on humidity, on how clean the stone is and on how you breathe on it. Unreliable in both directions.
The newspaper or dot read-through test for diamond
The claim is that you cannot read print through a real diamond. Depends entirely on the cut. A poorly cut diamond leaks light and you can read through it; a well-cut cubic zirconia or moissanite will not let you. The test measures the cut, not the material.
The scratch-glass test
Anything above about 5.5 on the Mohs scale scratches window glass. That includes quartz, topaz, garnet, spinel, cubic zirconia and hardened steel. Scratching glass narrows the field slightly and proves nothing.
The ultraviolet or "real ruby glows" test
Stated backwards more often than not. Chromium-bearing corundum does fluoresce red under long-wave ultraviolet — and flame-fusion synthetic ruby typically fluoresces more strongly than natural, because it lacks the iron that quenches fluorescence in many natural stones. A strong glow is, if anything, a mild point against natural origin. Meanwhile many genuine blue sapphires are inert.
The milk test and the water-bowl test
The claim that a genuine ruby placed in milk turns it pink, or that a genuine stone changes the colour of water, is folklore with no physical mechanism. Corundum is chemically inert; it does not leach colour. Any stone that does colour a liquid is dyed, which is useful information about the dye and none at all about the species.
The "if it feels cold it is real" test
Directionally true — dense crystalline materials do feel cooler and warm more slowly than plastic — and far too coarse to act on. Glass also feels cold. So does cubic zirconia. It separates gems from plastic and nothing else.
The "flawless means fake, included means real" rule
A useful instinct pushed too far. Inclusions are evidence of natural origin only when they are the right kind of inclusion. Synthetics are routinely manufactured with deliberate inclusions to look natural, and some natural stones genuinely are very clean. Read character, not quantity.
Wearing a stone for a trial period as an authenticity test
Some traditions recommend wearing a gemstone for a trial period before committing to it, and that is a customary practice with its own reasoning. It is not, and cannot be, a test of what the stone is made of. Material identity is a laboratory question. Keep the two separate.
What a laboratory report does and does not prove
What it establishes. The species and variety of the stone; whether it is natural or synthetic; the treatments detected and their extent; weight, measurements, cut and colour description. On a good report, all of that is tied to photographs and to a report number. That is the answer to the question you are actually asking.
What it does not establish.
- It does not price the stone. A report is an identification, not a valuation.
- It does not guarantee origin. Geographic origin reports exist and are expert opinions based on inclusion and trace-element evidence, not certainties. Many reports do not attempt origin at all.
- It says nothing about astrological suitability. No laboratory tests that, and any document implying otherwise is being misrepresented. Which stone suits a chart is a question for a qualified astrologer with your full birth details — see our guides on stones by rashi and who is customarily advised against which stone.
- It does not travel between stones. Match the weight and the millimetre measurements on the report against the stone itself, with a scale and a gauge, before it is set. Once a stone is in a closed setting, most of the tests above become impossible.
- An unnamed laboratory is not a laboratory. Look for the laboratory's name, a report number that can be looked up, the method, and a photograph. In-house certificates are marketing documents; they may be sincere, but they are not third-party evidence.
- Watch for the missing line. The most common way a report misleads is by omission — no treatment section at all, so nothing has technically been claimed.
Our own position, stated plainly: Divine Hindu holds government laboratory certification for Karungali ebony wood only. We do not claim it for gemstones, and for gems the right document is a report from a recognised gemmological laboratory naming the specific stone. Our approach across categories is on the lab certification page.
Price as a signal: why a cheap Navratna cannot be real
This is the most useful arithmetic in the article. Four of the nine — diamond, ruby, emerald and blue sapphire — are among the highest-value materials on earth per carat. Even at a quarter carat each, in commercial qualities, those four alone put a floor under a genuine natural Navratna that no manufacturing efficiency can get beneath. Add five more natural stones, nine individual settings and the labour, and the arithmetic is unforgiving.
| What you see | What it usually means |
|---|---|
| A nine-stone Navratna ring for a few thousand rupees | Synthetics, glass or a mixture. The diamond alone would exceed that at any natural quality. |
| All nine stones perfectly clean and vividly coloured | Natural stones of nine different species do not arrive matched like that. Uniform perfection is a manufacturing signature. |
| One certificate for the whole piece | Meaningless. Each stone needs its own identification, and reputable sellers of natural Navratna provide exactly that. |
| A ruby that is large, clean, deeply red and inexpensive | Overwhelmingly likely to be glass-filled corundum or flame-fusion synthetic. |
| Cat's eye with a razor-sharp, chalk-white, perfectly straight band | Fibre-optic glass. Look at the flat back for a honeycomb of hexagonal fibre ends. |
| "Natural pearls" at accessible prices | Almost certainly cultured, which is fine — but the word is being used loosely, and that tells you how the rest of the description was written. |
| A very high price with no report | Expense is not evidence. Overpriced synthetics are as common as cheap ones. |
An honest and widely used alternative deserves a mention: many people wear a Navratna set in declared synthetic or semi-precious substitutes, or wear a single prescribed stone in natural quality instead of nine in doubtful quality. Whether an upratna substitute is acceptable is a question of tradition and of your astrologer's view, not of gemmology. What matters here is that it be declared.
What to ask a seller, in writing
- For each stone: natural, synthetic, or imitation? Ask stone by stone, not about the piece as a whole.
- What treatments has each stone had? Heat, irradiation, dye, oil, resin, glass filling — name them.
- Which laboratory issued the report, and what is the report number? Then look it up.
- Is there a separate report for each of the nine? There should be.
- What are the weight and the millimetre measurements of each stone? Match them to the report before setting.
- Was the report issued on the loose stone or after setting? Before setting is far more informative.
- Is the ruby glass-filled? Ask it in those exact words. It is the single most common undisclosed condition in the Indian ruby market.
- Is the cat's eye chrysoberyl, quartz, or glass? Again, exact words.
- What happens if independent testing disagrees with your description? The question that separates the market.
- Will the species, treatment and weight of each stone appear on the invoice?
Where fakes enter the market
- Astrological consultations that end in a sale. Where the person recommending the stone also supplies it, the incentive to verify disappears. Buying the stone from someone other than the person who prescribed it is a simple and effective safeguard.
- Tourist and pilgrimage markets, particularly around gem-trade towns, where a convincing story and a laminated certificate travel together.
- Open marketplaces, where "certified" appears in listing titles with no laboratory named anywhere on the page.
- Set pieces sold without loose-stone reports. Setting is the single most effective way to prevent examination, which is why loose-stone certification matters.
- Family and inherited pieces. Not fraud, but genuinely unknown — old Navratna work frequently contains doublets and glass that were normal at the time.
- Live-stream and social selling, where the on-camera authenticity demonstration is nearly always the fog test, the scratch test or a torch shone through the stone — the three that answer least.
The same problem in other materials
Gemstones are the hardest category, but the pattern repeats everywhere: a price gap creates a substitution economy, and the tests that work are the ones tied to a physical property the fake cannot reproduce. Companion guides on the crystals most often bought alongside Navratna: natural citrine versus heat-treated amethyst, rose quartz, natural versus dyed, green aventurine and aventurescence, tiger's eye and chatoyancy, Sphatik versus glass, original versus fake pyrite and money magnet bracelets, stone by stone. Outside minerals: original versus fake rudraksha, original versus fake Karungali, original versus fake Tulsi mala and original versus fake Chandan. On wearing: how a gemstone is customarily worn.
Frequently Asked Questions
How can I tell if a gemstone is real or fake?
Use a 10x loupe and read the character of the inclusions rather than counting them. Natural stones show mineral crystals, fingerprint-like healed fractures, needles, and straight or angular colour zoning. Glass shows round bubbles, swirl lines, softened facet edges and sometimes a mould seam. Flame-fusion synthetic corundum shows curved colour banding and free spherical bubbles. The one distinction that catches most glass is this: a bubble inside a liquid-filled cavity is natural, while a free bubble sitting in solid material is not. For certainty, get a report from a named gemmological laboratory.
Are lab-grown gemstones fake?
Not in the material sense. A synthetic ruby is genuinely corundum, with the same chemistry and crystal structure as a natural one, and sold as synthetic it is an honest product at an honest price. It becomes fraud only when it is sold as natural. Tradition prescribes natural stones for the Navratna, and that preference is a matter of custom and belief. The testable reason to insist on natural is financial: you are paying a natural-stone price, and a synthetic is worth a small fraction of it.
Why is a cheap Navratna ring almost never genuine?
Because of arithmetic. Four of the nine gems — diamond, ruby, emerald and blue sapphire — are among the most valuable materials on earth by weight. Even at a quarter carat each in commercial quality, those four alone put a floor under a natural Navratna that no manufacturing efficiency can get below, before you add five more natural stones, nine settings and the labour. A nine-stone ring at a few thousand rupees is a different product sold under the Navratna name, usually synthetics, glass or a mixture of both.
What is glass-filled ruby, and why does it matter?
It is heavily fractured low-grade corundum impregnated with high-lead glass so that it looks clean and richly coloured. By weight it is largely real ruby, but it is structurally compromised: it can be damaged by lemon juice, by ultrasonic cleaners and by a jeweller's torch during repairs. Under magnification the filled fractures show a distinctive blue or orange flash as the stone is tilted, and often flattened gas bubbles. It is worth a small fraction of untreated ruby and it dominates the low-priced end of the Indian market, so ask about it in exactly those words.
How do I spot fake cat's eye, or Lehsunia?
The dominant fake is fibre-optic glass, a manufactured bundle of fine glass fibres cut so the fibre ends form a bright band. Two tells give it away. The eye is unnaturally sharp, perfectly straight and chalky white, where genuine chrysoberyl shows a softer, silkier band that opens and closes as the stone is rocked. And the flat back of the cabochon, under a loupe, shows a honeycomb of hexagonal fibre ends. Good chrysoberyl also shows the milk and honey effect, one side of the eye lighter and one darker under a single light.
Do air bubbles always mean a gemstone is fake?
Not quite, and the nuance matters. Free, spherical bubbles sitting in solid material indicate glass or a flame-fusion synthetic, so they are a strong warning. But natural stones commonly contain two-phase and three-phase inclusions — a liquid-filled cavity that itself contains a small gas bubble, and sometimes a tiny crystal as well. Those are evidence of natural origin, not against it. The skill is in seeing whether the bubble sits inside something or floats free.
Is the fog test reliable for diamond?
No. The claim is that a real diamond clears instantly because it conducts heat exceptionally well, which is true of diamond — and also true of moissanite, the imitation you are most likely to meet. The result also depends on humidity, on how clean the stone is and on how you breathe on it. The read-through-newspaper test is equally unreliable, because it measures the cut rather than the material: a poorly cut diamond can be read through and a well-cut cubic zirconia cannot.
Does real ruby glow under ultraviolet light?
Often, and that is not the proof it is presented as. Chromium-bearing corundum does fluoresce red under long-wave ultraviolet, but flame-fusion synthetic ruby typically fluoresces more strongly than natural material, because it lacks the iron that quenches fluorescence in many natural stones. A strong glow is, if anything, a mild point against natural origin rather than for it. Many genuine blue sapphires are completely inert. Fluorescence is a supporting observation for a trained observer, never a home test.
How do I check red coral, or Moonga?
Look for structure and test for dye. Genuine Corallium shows fine parallel striations along its length and a wavy radial pattern at a cut end. Dyed bamboo coral shows concentric growth rings and colour concentrated in cracks and pores; sponge coral is visibly porous. A cotton bud dampened with acetone or nail-polish remover, wiped firmly on an inconspicuous area, lifts colour from dyed material and leaves genuine coral unchanged. Do it before the stone is set. Trade in several coral species is internationally regulated, so provenance is a fair question to ask.
What should a gemstone certificate actually say?
It should name the issuing laboratory, carry a report number you can look up, and state the species and variety, whether the stone is natural or synthetic, every treatment detected and its extent, the weight, the millimetre measurements, the cut and the colour, with a photograph. Match the weight and measurements against the stone with a scale and a gauge before it is set. Be alert to omission: the commonest way a report misleads is by having no treatment section at all, so that nothing has technically been claimed. A certificate with no named laboratory is a marketing document.
Visit us or order online
If you want a Navratna piece you can examine against everything on this page, the Nine Gems Navratna Stones Mala we stock is the traditional nine-stone arrangement used for daily wear, in a strung form rather than a closed setting — which means the beads can be turned, loupe-checked and compared against each other in a way that a bezel-set ring does not allow. Read the description for what each stone is before you buy, and hold us to exactly the standard this article sets for anyone else. For prescribed single stones, or to look at material in person, visit Divine Hindu Store, Jayanagar 3rd Block East, Bengaluru 560011. Related reading: Navratna nine gems guide · rashi stone chart · how a gemstone is customarily worn · who is advised against which stone.
