Magnetism of Gemstones — Magnet Response Chart
Last updated: August 2026
Magnetic response for 130 gemstone species, sorted strongest first. 19 species show a response to a strong neodymium magnet — dominated by the iron- and manganese-bearing garnets — while 111 show none.
Common magnetism lookups: Almandine Garnet Strong · Rhodolite Garnet Strong · Demantoid Garnet Strong · Hematite Strong · Pyrope Garnet Moderate · Peridot Weak · Sapphire None · Diamond None
Magnetic testing uses a small, powerful neodymium magnet to probe a gem's iron and manganese content. Most gem species show no response at all, which makes the exceptions valuable: a visible drag or pickup instantly shortens the candidate list. The test is popular with collectors because it is cheap, non-destructive, and works on mounted and rough material alike — suspend the stone (a hanging thread, a float on water, or a low-friction surface) and bring the magnet close.
The garnet group dominates the responsive end of this chart. Recorded as strongly responsive: almandine garnet, demantoid garnet, hematite, rhodolite garnet, star diopside, star garnet. Moderately responsive: color-change garnet, malaya / umbalite garnet, pyrope garnet, rhodonite, spessartite garnet. That pattern is diagnostic in practice — a red stone that drags toward an N52 magnet is a garnet, not a ruby or red spinel, before any instrument comes out of the case.
Read the responses with care: "strong" here means a distinct attraction on a suspended stone, not that the stone snaps to the magnet like steel. Response scales with iron/manganese concentration, so it varies within a species, and small stones show relatively stronger reactions than large ones. Use magnetism as a fast screening test, then confirm with RI and SG.
Studying for the GIA or FGA practical? GemID drills the property calls that separate look-alike stones and runs timed mock exams built around the real exam formats.
Practice exams →| Gem | Magnetic Response | SG (typical) | Crystal System |
|---|---|---|---|
| Almandine Garnet | Strong | 4.05 | Cubic |
| Demantoid Garnet | Strong | 3.84 | Cubic |
| Hematite | Strong | 5.28 | Trigonal |
| Rhodolite Garnet | Strong | 3.84 | Cubic |
| Star Diopside | Strong | 3.29 | Monoclinic |
| Star Garnet | Strong | 4.05 | Cubic |
| Color-Change Garnet | Moderate | 3.72 | Cubic |
| Malaya / Umbalite Garnet | Moderate | 3.75 | Cubic |
| Pyrope Garnet | Moderate | 3.78 | Cubic |
| Rhodonite | Moderate | 3.60 | Triclinic |
| Spessartite Garnet | Moderate | 4.15 | Cubic |
| Black Spinel | Weak | 3.60 | Cubic |
| Hawk's Eye | Weak | 2.65 | Trigonal |
| Iolite | Weak | 2.59 | Orthorhombic |
| Kornerupine | Weak | 3.33 | Orthorhombic |
| Nephrite | Weak | 2.95 | Aggregate |
| Peridot | Weak | 3.34 | Orthorhombic |
| Sphene | Weak | 3.53 | Monoclinic |
| Tiger's Eye | Weak | 2.65 | Trigonal |
| Agate | None | 2.61 | Trigonal |
| Alexandrite | None | 3.73 | Orthorhombic |
| Amazonite | None | 2.56 | Triclinic |
| Amber | None | 1.08 | Amorphous |
| Amethyst | None | 2.65 | Trigonal |
| Ametrine | None | 2.65 | Trigonal |
| Andalusite | None | 3.17 | Orthorhombic |
| Apatite | None | 3.20 | Hexagonal |
| Aquamarine | None | 2.72 | Hexagonal |
| Aventurine | None | 2.65 | Trigonal |
| Benitoite | None | 3.66 | Hexagonal |
| Black Opal | None | 2.10 | Amorphous |
| Bloodstone | None | 2.61 | Trigonal |
| Blue Diamond | None | 3.52 | Cubic |
| Brown Diamond | None | 3.52 | Cubic |
| Carnelian | None | 2.61 | Trigonal |
| Cassiterite | None | 6.95 | Tetragonal |
| Cat's Eye Chrysoberyl | None | 3.73 | Orthorhombic |
| Chalcedony | None | 2.61 | Trigonal |
| Charoite | None | 2.60 | Monoclinic |
| Chrome Diopside | None | 3.30 | Monoclinic |
| Chrome Tourmaline | None | 3.10 | Trigonal |
| Chrysoberyl | None | 3.73 | Orthorhombic |
| Chrysocolla | None | 2.20 | Amorphous |
| Chrysoprase | None | 2.61 | Trigonal |
| Cinnabar | None | 8.10 | Trigonal |
| Citrine | None | 2.65 | Trigonal |
| Clinohumite | None | 3.21 | Monoclinic |
| Color-Change Sapphire | None | 4.00 | Trigonal |
| Coral | None | 2.68 | Aggregate |
| Cubic Zirconia | None | 5.80 | Cubic |
| Cuprite | None | 6.14 | Cubic |
| Danburite | None | 3.00 | Orthorhombic |
| Diamond | None | 3.52 | Cubic |
| Diaspore | None | 3.35 | Orthorhombic |
| Emerald | None | 2.72 | Hexagonal |
| Enstatite | None | 3.27 | Orthorhombic |
| Fire Opal | None | 2.00 | Amorphous |
| Fluorite | None | 3.18 | Cubic |
| Goshenite | None | 2.72 | Hexagonal |
| Grandidierite | None | 2.95 | Orthorhombic |
| Green Tourmaline | None | 3.06 | Trigonal |
| Grossular Garnet | None | 3.61 | Cubic |
| Hackmanite | None | 2.27 | Cubic |
| Hauyne | None | 2.47 | Cubic |
| Heliodor | None | 2.72 | Hexagonal |
| Hessonite Garnet | None | 3.61 | Cubic |
| Hiddenite | None | 3.18 | Monoclinic |
| Howlite | None | 2.53 | Monoclinic |
| Indicolite | None | 3.06 | Trigonal |
| Ivory | None | 1.85 | Aggregate |
| Jadeite | None | 3.34 | Aggregate |
| Jet | None | 1.32 | Amorphous |
| Kunzite | None | 3.18 | Monoclinic |
| Kyanite | None | 3.68 | Triclinic |
| Labradorite | None | 2.70 | Triclinic |
| Lapis Lazuli | None | 2.75 | Aggregate |
| Larimar | None | 2.80 | Triclinic |
| Low-Type Zircon | None | 4.00 | Tetragonal |
| Malachite | None | 3.80 | Monoclinic |
| Moissanite | None | 3.22 | Hexagonal |
| Moldavite | None | 2.35 | Amorphous |
| Moonstone | None | 2.58 | Monoclinic |
| Morganite | None | 2.82 | Hexagonal |
| Obsidian | None | 2.40 | Amorphous |
| Onyx | None | 2.61 | Trigonal |
| Opal | None | 2.15 | Amorphous |
| Padparadscha Sapphire | None | 4.00 | Trigonal |
| Paraiba Tourmaline | None | 3.06 | Trigonal |
| Pearl | None | 2.74 | Aggregate |
| Phenakite | None | 2.96 | Trigonal |
| Pietersite | None | 2.61 | Aggregate |
| Pink Diamond | None | 3.52 | Cubic |
| Pink Sapphire | None | 4.00 | Trigonal |
| Prasiolite | None | 2.65 | Trigonal |
| Prehnite | None | 2.88 | Orthorhombic |
| Rainbow Moonstone | None | 2.70 | Triclinic |
| Red Beryl | None | 2.68 | Hexagonal |
| Rhodochrosite | None | 3.50 | Trigonal |
| Rock Crystal | None | 2.65 | Trigonal |
| Rose Quartz | None | 2.65 | Trigonal |
| Rubellite | None | 3.06 | Trigonal |
| Ruby | None | 4.00 | Trigonal |
| Sapphire | None | 4.00 | Trigonal |
| Scapolite | None | 2.63 | Tetragonal |
| Serpentine | None | 2.55 | Monoclinic |
| Sinhalite | None | 3.48 | Orthorhombic |
| Smoky Quartz | None | 2.65 | Trigonal |
| Sodalite | None | 2.27 | Cubic |
| Sphalerite | None | 4.09 | Cubic |
| Spinel | None | 3.60 | Cubic |
| Star Ruby | None | 4.00 | Trigonal |
| Star Sapphire | None | 4.00 | Trigonal |
| Sugilite | None | 2.76 | Hexagonal |
| Sunstone | None | 2.63 | Triclinic |
| Synthetic Color-Change Corundum | None | 4.00 | Trigonal |
| Synthetic Spinel | None | 3.63 | Cubic |
| Taaffeite | None | 3.61 | Hexagonal |
| Tanzanite | None | 3.35 | Orthorhombic |
| Thulite | None | 3.20 | Orthorhombic |
| Topaz | None | 3.53 | Orthorhombic |
| Tourmaline | None | 3.06 | Trigonal |
| Tsavorite Garnet | None | 3.61 | Cubic |
| Turquoise | None | 2.76 | Triclinic |
| Variscite | None | 2.52 | Orthorhombic |
| Watermelon Tourmaline | None | 3.06 | Trigonal |
| White Sapphire | None | 4.00 | Trigonal |
| YAG | None | 4.55 | Cubic |
| Yellow Diamond | None | 3.52 | Cubic |
| Yellow Sapphire | None | 4.00 | Trigonal |
| Zircon | None | 4.69 | Tetragonal |
Click a column header to re-sort the table.
Which gemstones are attracted to a magnet?
19 of the 130 species in this chart show a recorded response to a strong neodymium magnet. Strong: Almandine Garnet, Demantoid Garnet, Hematite, Rhodolite Garnet, Star Diopside, Star Garnet. Moderate: Color-Change Garnet, Malaya / Umbalite Garnet, Pyrope Garnet, Rhodonite, Spessartite Garnet. Weak: Black Spinel, Hawk's Eye, Iolite, Kornerupine, Nephrite, Peridot, Sphene, Tiger's Eye.
Why are garnets magnetic?
Garnets carry iron and/or manganese as essential components of their chemistry rather than as traces — almandine and rhodolite are iron-rich, spessartite is manganese-rich — so they respond to a strong magnet far more than most gems. The response helps separate garnets from look-alikes such as ruby and red spinel, which show none.
Can a magnet test damage a gemstone?
No — magnetic testing is completely non-destructive and non-contact. It works on loose, mounted, rough, and polished material. Its limits are sensitivity (the stone must move freely to reveal weak responses) and specificity: a response brackets the iron/manganese-bearing candidates but never identifies a species on its own.
All instrument charts: Refractive Index · Specific Gravity · Mohs Hardness · Birefringence · Fluorescence · Pleochroism · Spectroscope · Optic Character · Chelsea & Hanneman Filters · Dispersion
See also: Full Reference Database · How to Identify a Gemstone · Exam Study Guides
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