A gemstone identification chart is worth making only if it answers the question you actually have in your hand: what else looks like this, and which property splits them? Color charts fail that test. Emerald green is also peridot, chrome diopside, green tourmaline, glass, and dyed quartz. The chart below is organized the way a careful amateur can use it. Each row gives the mineral, a realistic Mohs hardness range, the colors you should expect, and the confusion that causes bad labels in shops and inherited jewelry boxes.
Hardness is a scratch-resistance rank from 1 to 10. The steps are not equal. The jump from quartz at 7 to corundum at 9 is larger, in practical terms, than the jump from gypsum at 2 to calcite at 3. Household references still help on rough material: a fingernail is about 2.5, a copper coin about 3.5, a steel knife about 5 to 6.5, and ordinary window glass about 5.5. A stone that scratches glass is harder than 5.5. A stone that glass scratches is softer. Do not scratch a faceted gem, a cabochon with a good polish, or anything in a setting. Use hardness on rough edges, broken crystals, and the back of a low-value piece. For finished jewelry, use the chart to decide which lookalikes are even plausible, then stop.
Rock Identifier: Find Stone can propose a name from a photo before you touch the chart. Come back to the row for that name and read the confusion column before you accept it.
The chart
Ranges cover the common gem varieties of that mineral. A few trade names hide a different species, and those traps are called out under the table.
| Mineral (gem names) | Hardness | Typical color | Common confusion |
|---|---|---|---|
| Diamond | 10 | Colorless, yellow, brown; rare pink, blue, green | Moissanite (about 9.25), cubic zirconia (about 8–8.5), white sapphire (corundum, 9), colorless topaz (8), glass |
| Corundum (ruby, sapphire) | 9 | Ruby red; sapphire blue, pink, yellow, orange, green, colorless | Red spinel (8), garnet (about 6.5–7.5), red tourmaline (7–7.5), glass; blue spinel and tanzanite for blue sapphire |
| Chrysoberyl (alexandrite, cat's-eye) | 8.5 | Yellow-green; alexandrite shifts green in daylight toward red in incandescent light | Peridot, yellow sapphire, green tourmaline; alexandrite is often confused with color-change garnet or glass |
| Topaz | 8 | Colorless, blue, pink, yellow, sherry brown | Citrine and smoky quartz (7), aquamarine (7.5–8), glass. Blue topaz in shops is often irradiated and heated colorless topaz |
| Spinel | 8 | Red, pink, blue, lavender, black, colorless | Ruby and sapphire historically; red spinel was sold as ruby for centuries. Also garnet and glass |
| Beryl (emerald, aquamarine, morganite, heliodor) | 7.5–8 | Emerald green, blue-green aqua, pink, yellow-gold | Green tourmaline, chrome diopside (5.5–6), peridot, glass, dyed quartz. Aquamarine is confused with blue topaz |
| Quartz (amethyst, citrine, rose quartz, smoky, rock crystal) | 7 | Purple, yellow, pink, brown, colorless; crypto-crystalline agate and jasper are the same chemistry | Glass, fluorite (4), dyed agate sold as amethyst, heat-treated amethyst sold as citrine, topaz |
| Garnet group | about 6.5–7.5 | Almandine red, pyrope red, spessartine orange, grossular green to cinnamon, tsavorite green, demantoid green | Ruby, red spinel, red glass. Demantoid is confused with peridot and emerald. Grossular "hessonite" is confused with citrine and spessartine |
| Tourmaline | 7–7.5 | Pink, green, watermelon, blue, yellow, black | Beryl of the same color, peridot, glass. Paraíba-type copper tourmaline is confused with apatite and glass because of the neon blue-green |
| Peridot (olivine) | 6.5–7 | Yellow-green to olive, always in that family | Emerald, green tourmaline, green glass. Peridot is rarely bluish and is almost never a pure grass green without yellow |
| Jadeite | 6.5–7 | Imperial green, lavender, white, black, mottled | Nephrite, serpentine, aventurine quartz, dyed chalcedony, glass. "Jade" on a tag does not say which mineral |
| Nephrite | 6–6.5 | Cream to spinach green, often fibrous on a break | Jadeite, serpentine (about 2.5–5.5), vesuvianite. Nephrite is tougher than its hardness suggests because of interlocking fibers |
| Chalcedony (agate, carnelian, chrysoprase, onyx in the quartz sense) | 6.5–7 | Banded gray, orange-red, apple green, black-and-white bands | Glass, dyed howlite, jasper. Chrysoprase is confused with jade and with dyed green chalcedony |
| Feldspar gems (moonstone, sunstone, labradorite, amazonite) | 6–6.5 | Colorless to peach sheen; golden glitter; gray with blue-green flash; blue-green | Moonstone versus milky opal or chalcedony; amazonite versus turquoise and dyed stone; labradorite versus lower-quality spectrolite labels |
| Opal | 5.5–6.5 | Play-of-color on white, black, or colorless body; also potch with no play | Glass and resin imitations, moonstone. Body tone and a too-perfect color patch are warning signs, not proof |
| Turquoise | 5–6 | Sky blue to greenish blue, often with brown or black matrix | Dyed howlite, dyed magnesite, chrysocolla (2–4), variscite (3.5–4.5), plastic |
| Lapis lazuli | 5–5.5 | Deep blue rock, often with pyrite specks and white calcite | Sodalite (no pyrite), dyed jasper, glass. Lapis is a rock, not a single mineral |
| Apatite | 5 | Blue, green, yellow | Paraíba tourmaline, beryl, glass. Hardness is the split: apatite is scratched by quartz and often by a knife |
| Fluorite | 4 | Purple, green, yellow, blue, banded | Amethyst, apatite, glass. Octahedral cleavage gives flat triangular chips quartz never shows |
| Malachite | 3.5–4 | Light and dark green bands, opaque | Chrysocolla, dyed agate, plastic. Real malachite is soft and heavy for its size and bands in swirling eyes |
| Calcite and aragonite (including much banded "onyx" décor stone and cave onyx) | 3 (calcite); 3.5–4 (aragonite) | White, honey, orange banded | Quartz onyx, which is chalcedony and much harder. Calcite fizzes in cold dilute vinegar; quartz does not |
Trade-name traps that do not deserve their own row: "smoky topaz" is usually smoky quartz. "Oriental topaz" in old jewelry language was yellow sapphire. "Madras pearl" and similar phrases are not a hardness problem, but they are a reminder that the word on a tag can be a place or a fashion name rather than a species. "Onyx" in home décor is often banded calcite, while "onyx" in a gem tray is often black chalcedony. The chart's calcite and chalcedony rows are how you separate those two products. A drop of vinegar on a hidden powder scratch fizzes for the calcite décor stone. It does nothing to chalcedony.
How to use the chart without damaging the stone
Start with the color only long enough to collect two or three rows. A red stone might be ruby, red spinel, garnet, red tourmaline, or glass. Those rows span hardness 6.5 to 9. That spread is the whole identification if you are allowed to test. If you are not allowed to test, the chart still tells you what a photo cannot settle.
Then check transparency and luster against the row. Peridot is transparent to translucent and greasy-glassy, never opaque and waxy. Malachite is opaque and banded, never a clear green crystal. Turquoise is opaque and waxy to porcelaneous. Chrysoprase is translucent and the color is in the chalcedony, not painted on the back. If the row says "transparent" and you are holding a chalky cabochon, you are on the wrong row even when the color matches.
Crystal shape helps on rough pieces and is useless on most cabochons. Corundum often shows a barrel or spindle shape. Quartz grows in six-sided prisms with a pointed termination. Garnet is commonly a rounded dodecahedron. Fluorite cubes and octahedra are obvious once you have seen one. Tumbled gravel has had those shapes removed. For tumbled stones, go back to hardness and to whether color is even or only skin-deep.
Specific gravity is the next honest test when hardness is off limits. Gems of the same size do not weigh the same. Diamond is dense. Opal is noticeably light. Plastic turquoise is light and warm to the touch. You do not need a hydrostatic scale to notice that a "turquoise" nugget feels like a plastic bead. You do need a scale if you are trying to separate spinel from garnet in the same color, and at that point a gemologist is a better use of the afternoon.
Diamond and the colorless row
Colorless is the row where money and mistakes meet. Diamond at 10 will scratch corundum. You should not demonstrate that on either stone. What you can see is more practical. Diamond's high refractive index throws sharp white and colored flashes, and the facet edges look crisp under a 10× loupe. Glass looks sleepy by comparison and may show bubbles, swirl, or molded facet junctions that are slightly rounded. Cubic zirconia is heavy for its size and often too clean and too fiery in low-quality cuts. Moissanite is the modern problem: it is near 9.25, doubly refractive, and deliberately cut to look like diamond. A phone photo will not separate diamond from moissanite. A gemologist's thermal or electrical tester, used by someone who knows the false positives, is the appropriate tool. A gemstone identification chart can tell you that moissanite belongs on the suspect list. It cannot sign the receipt.
White sapphire is corundum, hardness 9, and it is a legitimate gem. It is also sold in place of diamond because the word "sapphire" sounds valuable. On the chart it sits with corundum, not with quartz. If a colorless stone scratches glass easily, you have only begun. Quartz, topaz, sapphire, moissanite, and diamond all scratch glass. Glass-scratching is a way to eliminate fluorite and calcite. It is not a way to prove diamond.
Ruby, sapphire, and the stones that borrowed their names
Corundum is aluminum oxide. Ruby is the red gem variety. Every other color is sapphire, including pink, yellow, and colorless. Hardness 9 puts corundum above every common lookalike except diamond and moissanite, which are not red. The historical mix-up is spinel. Spinel is also hard, also singly refractive in the sense collectors care about when they are comparing it with garnet, and also found in the same marble that produces ruby. Several famous "rubies" in old collections were later shown to be spinel. Garnet is softer and usually a darker, more brownish red, but a fine pyrope can be bright. Tourmaline often shows stronger color zoning and a different pleochroism: turn the stone and the color changes more obviously than in ruby.
None of that is visible in a single flash photo. Rock Identifier may return "ruby" for any saturated red crystal. Use that as permission to open this chart, not as permission to price the stone as corundum. Heat treatment is routine in the ruby and sapphire trade. Fracture filling and lead-glass composites sold as ruby are a separate, cheaper product. A chart will not show you filler in a fracture. A loupe sometimes will, as bubbles in the cracks. If the price depends on the answer, pay for a lab report.
Emerald, peridot, and the green problem
Emerald is green beryl. It is rarely free of inclusions. Those inclusions are not a defect in the identification sense; a suspiciously clean, evenly colored "emerald" at a flea market is often glass. Chrome diopside is a deep green that photographs like emerald and is much softer, about 5.5 to 6, so a careful hardness check on rough material separates it quickly. Peridot always carries yellow in the green. If the stone is olive and the setting is a simple claw from the late nineteenth or early twentieth century, peridot is a common and honorable answer. Green tourmaline can be either olive or a cooler green and is hard enough to overlap beryl, so hardness will not finish that pair. Pleochroism and refractive index will.
Jade is not a green beryl at all, and it usually is not transparent. If the piece is a carved bangle or a smooth cabochon with a dimpled polished surface, you are in the jadeite or nephrite rows, or in serpentine. Serpentine is the important soft fake. A steel point you would never use on emerald may be appropriate on the underside of a carving that is already nicked, because serpentine scratches and nephrite often does not. Even then, call it a screening test. Fine jadeite and nephrite are separated by structure and specific gravity more reliably than by a scratch.
Turquoise, lapis, and other soft blue stones
Turquoise is porous, soft, and widely imitated because the color sells itself. Dyed howlite and dyed magnesite take a blue dye and a fake matrix. Howlite is white with gray veins before it is dyed, and it is softer and more lightweight in feel than dense Persian or American turquoise. A cotton swab with acetone on a discreet spot can lift dye. It can also damage a stabilized stone's surface, so this is a test for a broken bead, not for a spotless necklace you hope to keep pristine. Chrysocolla is softer still and usually more green-blue and glassy in the pores. Plastic is light, and a hot needle — again, only on a sacrificial spot — smells like plastic rather than mineral. Do not hot-needle a stone you care about.
Lapis lazuli should show some pyrite or at least a slightly gritty mix of blue, white, and brassy flecks. Uniform royal-blue plastic with painted gold spots fails that look under a loupe. Sodalite is a real mineral, often bluer in a flat way, without pyrite, and it is a fair jewelry stone. It is not lapis. The chart keeps them apart because the confusion is a labeling problem more than a hardness problem. Both sit near 5 to 6.
Quartz varieties and the dyes
Quartz is the default honest answer for a huge amount of inexpensive jewelry, and it is also the canvas for dyes. Amethyst is purple quartz, hardness 7, and it occurs in obvious crystals. Purple fluorite is softer, cleaves, and should never be sold as amethyst once someone has seen both broken. Citrine is yellow quartz. A large share of commercial citrine is amethyst that was heated until the purple left. That is still quartz. It is not topaz. Rose quartz is usually hazy rather than a sharp crystal. Pink dyed agate often shows color gathered in the bands.
Agate, carnelian, and chrysoprase are quartz too, in the microcrystalline form called chalcedony. They take dye well. Bright magenta, electric blue, and neon green "agate" slices are often dyed. Natural chrysoprase is apple green from nickel and is not a harsh emerald green. If the color looks like a marker pen, assume dye until you know the dealer.
Opal needs its own caution
Opal is hydrated silica. It is softer than quartz and sensitive to sudden drying and to heat. A gemstone identification chart that only lists hardness will not stop someone from leaving an opal on a hot dashboard, where it can craze. Play-of-color is the spectral flash that moves as you tilt the stone. Body color is the background: white, black, or crystal. Imitations include glass with foil, resin chips, and assembled doublets and triplets in which a thin slice of real opal sits on a dark backing under a clear cap. A triplet seen from the side shows layers. That does not make it fake in the fraud sense if it was sold as a triplet. It does make "solid black opal" the wrong name. Softness is why opal is rarely a ring stone for daily wear. The chart's hardness column is a wearability warning as much as an identification tool.
Where Rock Identifier fits beside the chart
Use the app when you do not yet know which row you are on. A reasonable session looks like this. Photograph the stone dry, in open shade, with the facet or the cabochon dome filling the frame and a second shot of the setting or the rough exterior. Read the top two mineral names. Find both rows in the chart. If they share a hardness and a color, the app and the chart have done all they can together, and the next step is optical testing or a jeweler. If they sit far apart in hardness and the piece is rough, one discreet test resolves it. If the app says turquoise and the chart's confusion column says dyed howlite, you know exactly what to ask the seller.
The chart will not price a stone. Rarity, treatment, clarity, and cut move price more than the species name. Emerald and green glass can be the same size and the same setting. Only one of them is beryl. Identify the mineral first. Talk about money second.
A pocket sequence you can memorize
- Name the color in plain words, including modifiers: olive green, sky blue, brownish red.
- Note transparent, translucent, or opaque.
- Open the two or three matching rows.
- If the piece is rough and low value, test the hardness boundary that separates those rows.
- If the piece is set or polished, do not scratch it. Use the confusion column as a list of questions.
- For diamond, ruby, emerald, and jade prices, get a human report.
That sequence is the entire point of a gemstone identification chart. The numbers are stable. The names on paper tags are not. When a photo and a row agree, and a hardness or dye check does not contradict them, you have an identification good enough for a collection label. When money or safety is attached, the chart's last job is to tell you which lookalike you still have not ruled out.
Frequently Asked Questions
How do you use a gemstone identification chart on a finished jewel?
Match color and transparency to two or three rows, then read the confusion column. Do not scratch the gem. Differences you cannot see, such as diamond versus moissanite or natural versus dyed turquoise, need a jeweler or a lab.
What does Mohs hardness actually tell you?
It ranks which mineral scratches which. Quartz at 7 scratches glass and scratches fluorite. Diamond at 10 scratches corundum. It does not measure toughness, so nephrite jade can survive a knock that chips a harder but more brittle stone.
Why are ruby and red spinel on different rows?
Ruby is corundum, hardness 9. Red spinel is a different mineral, hardness 8. They have been mixed up for centuries because the colors overlap. A photo can suggest either one. Hardness or optical tests separate them.
Is jade one mineral on the chart?
No. Jadeite and nephrite are separate rows. Serpentine is the soft stone most often mistaken for both. A tag that only says "jade" has not told you which row you paid for.
Can vinegar identify a gemstone?
Only as a carbonate test. Calcite fizzes in cold dilute vinegar. Quartz, jade, and turquoise do not. Use a grain of powder from an existing scratch on décor stone, not a flood of acid on a gem.
Does a stone identifier app replace this chart?
It replaces the blank stare at the start. Rock Identifier proposes a mineral from a photo. The chart tells you whether a second mineral still fits that photo and which property would split them.
Download Rock Identifier Today
Put the chart to work on the next unknown stone in your hand. Rock Identifier: Find Stone suggests likely minerals from a photograph so you know which row to read, which lookalike still fits, and whether a hardness check is even allowed on that piece.
Download Rock Identifier on the App Store and keep the chart honest with a better first name.