Identify Gemstones By Color, Hardness, Transparency & Shape
Found an old stone in a drawer, inherited a ring, or picked up something at a flea market and now you’re wondering what it really is? You can narrow it down in about a minute. Tell this free gemstone identifier the stone’s color, how hard it is, how see-through it looks and what shape it’s cut in. It ranks the closest matches from our gemstone database, each with a percentage score. You don’t need to upload a photo.
Results are a starting point, not a lab report. If the stone might be valuable, read the section on when to get it professionally tested.
Identify Gemstones By Color
Answer 4 quick questions and we'll find your closest matches.
What color is it?
Pick the color that best matches your gemstone. If it shows more than one, choose the most dominant one.
How hard is it? (Mohs scale)
Not sure? A steel knife blade is about 5.5 — if it scratches the stone, pick a lower range.
How see-through is it?
Hold it up to a light. Transparent = see clearly through it, Translucent = light passes but blurry, Opaque = no light passes at all.
What shape is it cut in?
Round and oval are the most common cuts — pick "Other / not sure" if yours doesn't match any shape here.
This tool suggests likely gemstones based on what you observe. It is a starting point, not a laboratory identification.
How This Gemstone Identifier Works
Gemologists never identify a stone from looks alone, because any single clue can mislead. A red stone could be ruby, garnet, spinel or glass. So this tool works the way a gemologist thinks, just simplified: it compares several physical properties at once, using four you can check without special equipment.
- Color (35 points). Does the stone’s color match the colors recorded for each gemstone?
- Hardness (35 points). Does its Mohs hardness fall in the range you picked?
- Transparency (20 points). Is it transparent, translucent or opaque?
- Shape (10 points). What cut or form does the stone have?
Color and hardness carry the most weight because they separate gemstones best. Shape counts least, since almost any gem can be cut into almost any shape.
Each gemstone earns points for every property that matches. The total becomes the match percentage, and you see up to the five closest matches. A 90% match means nearly everything you reported lines up. A 50% match means some details fit and others don’t, so treat it as a lead to check, not an answer.
Click any result to open the full gemstone profile with everything we have on that stone, and download it as a PDF. If you pick “Not sure” on a step, that step stops separating one gem from another and the ranking leans on your other answers.
How to Identify a Gemstone at Home
You don’t need a lab for a first pass. These four checks, done in this order, get you surprisingly far.
1. Check the color in daylight
Look at the stone near a window in natural daylight. Warm indoor bulbs shift color and can make a blue stone look green or a pink one look orange. Turn it slowly and watch from several angles. Some gems, like tanzanite and alexandrite, show different colors depending on the angle or the light.
Pick the dominant color. Keep in mind that color is the least reliable clue on its own. Sapphire and quartz come in nearly every color, and many stones are heat-treated or dyed. Color is best used to shrink the list, then hardness and transparency finish the job.
2. Test hardness with the Mohs scale
The Mohs scale ranks minerals from 1 (talc) to 10 (diamond) by scratch resistance. It’s a relative scale: a 9 isn’t “a little harder” than an 8, it’s meaningfully harder. These everyday items make handy reference points:
- Fingernail: about 2.5
- Copper coin: about 3
- Steel knife blade or window glass: about 5.5
- Steel file: about 6.5
- Quartz: 7
Here’s the method. Pick a hidden spot on the stone, such as the edge or underside. Try to scratch it with items of known hardness, working from softest to hardest. Wipe the spot and look at it under a magnifier, because chalky residue from a softer material can look like a scratch and wipes away. Your stone’s hardness sits between the last item that couldn’t scratch it and the first one that could.
Only test loose, low-value or rough stones. Never scratch-test a faceted gem you care about or one set in jewelry, because a scratch is permanent and thin edges can chip.
One more thing: hardness is scratch resistance, not toughness. Diamond is a 10 but can still chip if struck at the wrong angle, and some hard gems, such as topaz, split along cleavage planes.
3. Judge the transparency
Hold the stone up to a light, or set it on a line of printed text. If you can read the letters clearly through it, it’s transparent. If light gets through but the text is blurry, it’s translucent. If no light passes at all, it’s opaque. Ruby, emerald and topaz are usually transparent. Jade and moonstone are often translucent. Turquoise and lapis lazuli are opaque.
4. Look at the shape and cut
Shape is the weakest clue, because cutters choose it to show off color, hide flaws or save weight. Still, it tells you something. Transparent stones are usually faceted to bring out sparkle. Opaque and translucent stones, like turquoise, jade and opal, are more often cut as cabochons: smooth and domed with no facets. If your stone is uncut, look at its natural crystal form. A six-sided prism, for example, points toward quartz.
Other clues worth noting
Luster (how the surface reflects light), weight in the hand, and inclusions all help. Round gas bubbles inside a stone point toward glass, while natural gems tend to show irregular needles, feathers or crystals. Properties like refractive index and specific gravity need instruments, which is where a gemologist comes in.
Gemstone Identification Chart: Mohs Hardness for Common Gems
Use this quick gemstone hardness chart to see where common stones fall. Ranges are typical and vary a little by variety.
| Gemstone | Mohs hardness |
|---|---|
| Diamond | 10 |
| Ruby, sapphire (corundum) | 9 |
| Alexandrite | 8.5 |
| Topaz | 8 |
| Spinel | 8 |
| Emerald, aquamarine (beryl) | 7.5–8 |
| Zircon | 7.5 |
| Tourmaline | 7–7.5 |
| Garnet | 6.5–7.5 |
| Amethyst, citrine, quartz | 7 |
| Peridot | 6.5–7 |
| Jadeite jade | 6.5–7 |
| Tanzanite | 6–7 |
| Moonstone | 6–6.5 |
| Opal | 5.5–6.5 |
| Turquoise | 5–6 |
| Lapis lazuli | 5–5.5 |
| Pearl | 2.5–4.5 |
| Amber | 2–2.5 |
Identify Gemstones by Color
Color is where most people start, so we’ve put together a guide for each one. Every page lists the gemstones we cover in that color, with Mohs hardness for each.
- Blue gemstones: sapphire, aquamarine, blue topaz, tanzanite and lapis lazuli. Hardness runs from about 5 to 9, so the hardness step does a lot of work here.
- Red gemstones: ruby, garnet and red spinel. Ruby and spinel are easy to confuse, as you’ll see below.
- Green gemstones: emerald, peridot, jade and malachite.
- Yellow gemstones: citrine, yellow sapphire, yellow topaz and golden beryl.
- Pink gemstones: morganite, kunzite, pink tourmaline, pink sapphire and rose quartz.
- Black gemstones: black onyx, black spinel, jet and black tourmaline.
- Orange gemstones: carnelian, spessartine garnet, fire opal and orange sapphire.
- Brown gemstones: smoky quartz, tiger’s eye and brown tourmaline.
- Gray gemstones: moonstone, hematite, gray spinel and labradorite.
- Multicolor gemstones: opal, labradorite and fluorite.
- Bi-color gemstones: ametrine, watermelon tourmaline and bi-color sapphire.
Gemstone Look-Alikes That Fool Almost Everyone
These pairs show why one property is never enough.
Ruby vs. red spinel
Both are red, and for centuries spinel passed as ruby. The “Black Prince’s Ruby” in Britain’s Imperial State Crown is actually a spinel. Ruby is a 9 and spinel an 8, which helps, but a gemologist confirms it with a refractometer or polariscope, because spinel is singly refractive and ruby is doubly refractive.
Citrine vs. yellow topaz
Citrine is a 7 and topaz is an 8, so hardness separates them in principle. Also worth knowing: much of the citrine on the market is heat-treated amethyst, because natural citrine is relatively rare.
Amethyst vs. purple fluorite
This one is easy. Amethyst is a 7, fluorite only a 4. Fluorite scratches with a steel knife and cleaves along flat planes. Amethyst won’t scratch with a knife.
Emerald vs. green glass
Glass sits around 5.5, while emerald is 7.5–8. Look inside too. Round gas bubbles point to glass, while natural emeralds usually show irregular, feathery inclusions that gemologists call jardin, French for “garden.”
Blue topaz vs. aquamarine
Here hardness barely helps: topaz is 8 and aquamarine 7.5–8. Deep, saturated blues are usually treated topaz, while aquamarine tends to be paler and softer in tone. For a certain answer you need refractive index, which is why no single test settles it.
Why Your Result Might Be Off, and What to Do Next
A few things can throw off any identification, ours included.
- Treatments. Heat, dye, irradiation and fracture filling can change a stone’s color or clarity without changing its type.
- Lab-grown stones. A synthetic ruby is chemically a real ruby, with the same hardness and color. Only a lab can separate it from a natural one.
- Imitations. Glass and cubic zirconia (hardness about 8–8.5) are made to look like more valuable stones.
- Natural variation. Color zoning, changing light and different varieties of the same species can all mislead.
If the stone might be valuable, or you plan to sell it, insure it or are dealing with inherited jewelry, get it checked. A local jeweler with a loupe is a quick first stop. For a formal identification, ask for a report from an accredited gemological laboratory such as GIA. Keep in mind that a lab identification report and an appraisal are different documents: one says what the stone is, the other says what it’s worth.
Gemstone Identifier FAQ
Yes. A photo only shows color, shape and surface appearance, which are the easiest properties to misjudge. Hardness and transparency often tell you more. This identifier uses four properties you can check yourself, so you don’t need to upload anything.
Yes, it’s free to use and there’s nothing to download.
It’s accurate enough to narrow a long list down to a handful of likely candidates, and that’s all it’s designed to do. Your answers set the ceiling: if color was judged under yellow light or hardness was a guess, the matches will drift. Confirming a stone’s identity with certainty takes lab equipment such as a refractometer or spectroscope.
Start with hardness and look for natural features. Real gemstones usually show tiny inclusions, while round gas bubbles suggest glass. “Real” can mean different things, though. A lab-grown ruby is chemically a real ruby, and a treated stone is a real gemstone with improved color. Only a gem lab can tell you whether a stone is natural, treated or synthetic.
Compare the stone with objects of known hardness: a fingernail is about 2.5, a copper coin about 3, a steel knife blade or window glass about 5.5, and a steel file about 6.5. Only test loose, low-value or rough stones, because scratch tests can mark a faceted gem for good.
Diamond, at 10 on the Mohs scale. Among colored gemstones, ruby and sapphire are the hardest at 9. Hardness measures scratch resistance, not toughness, so even a very hard stone can chip if struck at the wrong angle.
No. It suggests the likely type of stone, not its price. Value depends on color quality, clarity, cut, carat weight, treatments and origin, so a certified appraisal is the right next step for anything valuable.
Try “Not sure” on the step you’re least confident about, or re-check the color in daylight. If you still get nothing close, the stone may be an uncommon variety, a synthetic or an imitation, and a local jeweler or gem lab can take a look.
Ready to Identify Your Stone?
Scroll back up, pick a color and see what comes back. Start with the color you see in daylight, answer honestly on hardness, and use “Not sure” whenever you really aren’t. Then open the top match and compare the full profile with your stone.
This identifier is an educational guide. It isn’t an appraisal, a certification or a laboratory identification.