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Gemstone Hardness: Which Stones Are Best for Everyday Jewelry?
Gemstone Hardness: Which Stones Are Best for Everyday Jewelry?
Gemstone hardness is a stone's resistance to scratching, and jewelers measure it on the Mohs scale, which runs from 1 to 10. For jewelry you wear every day, rings above all, choose stones rated 7 or higher: diamond (10), ruby and sapphire (9), topaz (8), aquamarine and emerald (7.5 to 8), and amethyst and citrine (7). Softer stones such as opal, turquoise and pearl last longer in earrings and pendants.
Hardness only covers scratches, though. A stone also has to survive the odd knock against a car door, plus soap and hand cream. Below you will find the Mohs rating for every birthstone, why 7 is the number jewelers watch, and which settings help a softer stone last. If you only need to know your stone, our month-by-month birthstone finder has all twelve months.
Gemstone hardness at a glance
| Gemstone | Birth month | Mohs hardness | Everyday ring? | Best jewelry uses |
|---|---|---|---|---|
| Diamond | April | 10 | Yes | Any piece, including rings worn daily |
| Ruby | July | 9 | Yes | Rings, bracelets, any piece |
| Sapphire | September | 9 | Yes | Rings, bracelets, any piece |
| Alexandrite | June | 8.5 | Yes | Rings, earrings, pendants |
| Topaz, blue topaz | November, December | 8 | Yes, avoid hard knocks | Rings, earrings, pendants |
| Spinel | August | 8 | Yes | Rings, earrings, pendants |
| Aquamarine | March | 7.5 to 8 | Yes, with sensible care | Rings, earrings, pendants |
| Emerald | May | 7.5 to 8 | With care, in a protective setting | Earrings, pendants, bezel or halo rings |
| Tourmaline | October | 7 to 7.5 | Yes, with sensible care | Rings, earrings, pendants |
| Amethyst, citrine | February, November | 7 | Yes, with sensible care | Rings, earrings, pendants |
| Garnet | January | 6.5 to 7.5 | With care | Rings, earrings, pendants |
| Peridot | August | 6.5 to 7 | With care | Earrings, pendants, occasional rings |
| Zircon | December | 6 to 7.5 | Occasional wear | Earrings, pendants |
| Tanzanite | December | 6 to 7 | Occasional wear | Earrings, pendants |
| Moonstone | June | 6 to 6.5 | Occasional wear | Earrings, pendants |
| Opal | October | 5 to 6.5 | Occasional wear | Earrings, pendants |
| Turquoise | December | 5 to 6 | Occasional wear | Earrings, pendants |
| Pearl | June | 2.5 to 4.5 | Occasional wear | Earrings, necklaces, pendants |
Where the table gives a range, the figure shifts a little with the stone's exact composition. Garnet is a good example: it is a family of related minerals, and they do not all rate the same.
What the Mohs scale measures
The German mineralogist Friedrich Mohs devised the scale in 1812. He picked ten common minerals and ranked them by a simple test: which one scratches which. Any mineral will scratch the ones below it and be scratched by the ones above it.
| Mohs number | Reference mineral | Gemstones at about this level |
|---|---|---|
| 1 | Talc | None used in jewelry |
| 2 | Gypsum | None common |
| 3 | Calcite | Pearl (2.5 to 4.5) |
| 4 | Fluorite | Pearl |
| 5 | Apatite | Turquoise, opal |
| 6 | Orthoclase feldspar | Moonstone, tanzanite, opal |
| 7 | Quartz | Amethyst, citrine, garnet, peridot |
| 8 | Topaz | Topaz, spinel, aquamarine, emerald |
| 9 | Corundum | Ruby, sapphire |
| 10 | Diamond | Diamond |
The scale gives an order, not a measurement. The steps are not equal. On paper, sapphire at 9 sits one step below diamond at 10. In absolute terms the gap is far larger than that between 8 and 9, and diamond is many times harder than corundum. Read the numbers as a ranking.
Why 7 is the number to remember
Ordinary household dust contains fine grains of quartz, and quartz rates 7. Every time you wipe a ring on a towel or brush it against a coat, those grains rub across the stone. A gem softer than 7 slowly loses its polish this way, and its facet edges round off over the years. A gem at 7 or above shrugs most of that off.
That is why we treat 7 as the working line for rings worn every day. Rings meet more surfaces than any other kind of jewelry, so they take the most wear. For earrings and pendants the line matters much less.
Hardness, toughness and stability
A stone can be hard and still break. Gemologists look at three separate properties, and all three decide how a stone wears.
Hardness is resistance to scratching, which is what the Mohs scale ranks.
Toughness is resistance to chipping and breaking. Diamond is the hardest gem, yet it has cleavage, planes along which a sharp blow at the wrong angle can split it. Topaz rates 8 but has perfect cleavage, so a hard knock can split it as well. Emerald usually carries inclusions and tiny fractures, which make it less tough than its 7.5 to 8 suggests.
Stability is how a stone copes with heat, light, chemicals and sudden temperature changes. Opal can crack if it dries out or goes from hot to cold quickly. Pearl is damaged by acids, perfume, hairspray and cosmetics. Tanzanite does not like sudden temperature changes either.
For a ring you wear every day, check hardness first and toughness second. For earrings and pendants, you have far more choice.
The everyday stones: diamond, ruby and sapphire
At 9 and 10, these three handle daily wear better than any other birthstones. Ruby and sapphire are both corundum. Ruby is the red variety, and sapphire covers blue and the other colors. That shared mineral is why they rate the same. Lab-created ruby and sapphire are corundum too, with the same chemistry and the same hardness of 9, so a lab-created stone is just as practical in a ring.
The sapphire and ruby rings are 925 sterling silver with a polished finish, each set with a lab-created stone on a 3.5 mm band, and both are listed in size 7. They stack well with each other, which suits anyone born in July or September. The studs are 14K white gold with two lab-grown diamonds of 0.25 ct each, 1/2 ct in total, graded VS/SI+ clarity and G+ color. Each sits in a 3-prong basket and measures 4 mm. For more stones by month, see our September birthstone jewelry and July birthstone jewelry.
Strong choices from 7 to 8.5
Alexandrite (8.5), topaz and spinel (8), aquamarine (7.5 to 8), tourmaline (7 to 7.5) and the quartz stones, amethyst and citrine (7), all sit at or above the dust line. They make good rings for daily wear as long as you take them off for heavy work. Topaz is the one to watch for knocks, because of the cleavage mentioned above.
Aquamarine is a good example of this tier. It is a beryl, like emerald, but it usually grows much cleaner, with fewer inclusions to weaken it.
The ring is 14K yellow gold with a 6x4mm oval natural aquamarine held by four prongs and diamond accents along a slim 2mm band, in size 6. The studs are sterling silver with rhodium plating and carry 4mm round natural aquamarines, also in four-prong settings. Both listings note the aquamarine is heat-treated. That is routine for aquamarine: heating removes a greenish tint to leave a purer blue, and the color it produces is permanent. Our guide on how to choose a birthstone ring goes further into prong and bezel settings.
Amethyst and citrine sit exactly at 7, level with the quartz in dust. They wear well in rings that are not taking hard knocks all day. Garnet runs from 6.5 to 7.5 depending on the type, so most garnet rings handle regular wear with a little care.
The amethyst ring is sterling silver with rhodium plating. A single oval amethyst sits in a prong setting with heart shapes along the sides, on a 2 mm band, in sizes 5 to 10. The listing notes the amethyst is heat-treated. The garnet ring is polished sterling silver with one natural garnet on top of a 2.06 mm band, offered in sizes 6, 7 and 8. Browse more red stones in our January birthstone jewelry.
Emerald: hard, but not tough
Emerald is the stone that most often surprises people. It rates 7.5 to 8, harder than amethyst. Most mined emeralds contain inclusions and small fissures, though, and many are filled with oil or resin to improve their look. A sharp knock can chip one, and heat or harsh cleaners can draw out the filler.
From the Birthstone Company collection
A slim emerald ring for stacking
This ring is polished 925 sterling silver set with a lab-created emerald on a 3.6 mm band, in size 7. A lab-created emerald is still beryl, with the same chemistry and hardness as a mined one, so treat it the same way. Take it off for the gym and the garden. For an emerald you plan to wear daily, a bezel or a halo of small stones gives the edges extra protection.
Under 7: earrings and pendants
Peridot (6.5 to 7), tanzanite (6 to 7), moonstone (6 to 6.5), opal (5 to 6.5), turquoise (5 to 6) and pearl (2.5 to 4.5) all fall below the dust line. None of that rules them out. It just changes where they go. Earrings and pendants rarely hit anything, so a soft stone can look good in them for decades.
From the Birthstone Company collection
Softer stones, worn up high
Sterling Silver Rhodium-Plated Tanzanite & Diamond Drop Earrings Elegant Polished Finish
$103.78
View Piece →The round pendant is sterling silver with rhodium plating, set with a lab-created opal, and measures 17.5 mm long. The listing notes the opal is impregnated, a treatment that fills tiny pores with a stabilizing material, so keep it away from ultrasonic cleaners. The pearl studs are 14K yellow gold, each with a 2.5mm bleached white freshwater cultured pearl on a polished post. The tanzanite drops are rhodium-plated sterling silver, with a pear-shaped blue tanzanite beside a small white diamond, prong set, 8 mm wide and 21 mm long, on posts with push backs. Almost all tanzanite is heated to bring out its blue, and this pair is listed as heat-treated. Our October birthstone guide explains why tourmaline is often the easier October pick for a ring, and the December birthstone guide compares blue topaz at 8 with tanzanite and turquoise.
How the setting and jewelry type change things
Where a stone sits on the body matters as much as its number on the scale. This is roughly how we weigh it when suggesting stones:
| Jewelry type | Exposure to knocks | Hardness we suggest for daily wear |
|---|---|---|
| Rings | High: hands touch everything | 7 and up; 8 and up for a ring never taken off |
| Bracelets | Medium to high: desks, doors, counters | 7 and up |
| Earrings | Low | Any stone, including pearl and opal |
| Pendants and necklaces | Low | Any stone, including pearl and opal |
The setting adds another layer. A bezel wraps a rim of metal around the stone, which shields its edges and suits emerald, opal and tanzanite in a ring. Prongs let in more light but leave more of the stone exposed, so check them for wear about once a year. A halo of small stones takes the first bump before the center stone does, and a low setting that sits close to the finger catches less than a tall one. If you are choosing a pendant, our guide on how to choose a birthstone necklace covers lengths and styles.
Natural or lab-created: the hardness is the same
A lab-created ruby, sapphire or emerald has the same chemistry and crystal structure as the mined stone, so it has the same hardness. Growing a stone in a laboratory does not make it softer or harder. Clarity and treatments can differ, and each product page states which kind you are buying. Our lab-created gemstones collection gathers them in one place.
Caring for stones of different hardness
- Store pieces apart. A diamond will scratch every other gem, and a sapphire will scratch topaz, so give each piece its own pouch or compartment.
- Clean most stones with warm water, mild soap and a soft brush, then dry with a lint-free cloth.
- Keep emerald, opal, pearl, tanzanite and turquoise out of ultrasonic and steam cleaners, along with any stone a listing calls filled or impregnated.
- Put jewelry on after perfume, hairspray and lotion, which matters most for pearl and opal.
- Take rings off for the gym, gardening and housework, even hard ones. A diamond can still chip.
Our jewelry basics guide covers metals and care in more detail.
Gemstone hardness questions
What is the hardest gemstone?
Diamond, at 10 on the Mohs scale. Ruby and sapphire follow at 9. Diamond's hardness protects it from scratches, but it can still chip if it takes a sharp blow along its cleavage.
Is a hardness of 7 good enough for a ring?
Yes, for most people. Seven matches the quartz in household dust, so stones at 7, such as amethyst and citrine, resist everyday scratching. Stones at 8 and above give you more margin for a ring you never take off.
Which birthstones are not good for everyday rings?
Pearl (2.5 to 4.5), turquoise (5 to 6), opal (5 to 6.5), moonstone (6 to 6.5) and tanzanite (6 to 7). They are better in earrings and pendants, or in a ring worn now and then in a protective bezel setting.
Is emerald good for everyday wear?
With care. Emerald rates 7.5 to 8, but its inclusions make it less tough than that number suggests, so it chips more easily than its hardness implies. Choose a bezel or halo setting for a ring and keep it out of ultrasonic cleaners.
Do lab-created gemstones have the same hardness as natural ones?
Yes. A lab-created ruby, sapphire or emerald has the same chemistry and crystal structure as the mined stone, so it rates the same on the Mohs scale.
Is the Mohs scale linear?
No. It ranks minerals by which scratches which, so the steps are uneven. Diamond at 10 is many times harder than corundum at 9, although they sit one number apart.
What is the best colored gemstone for an engagement ring?
Sapphire and ruby are the usual choices, since both rate 9 and handle daily wear well. Alexandrite at 8.5 and spinel at 8 are good options too.
Related guides
See every month's stone in our November birthstone guide and the rest of the monthly guides. For ideas by recipient, read the birthstone jewelry gift guide. Planning a family piece? The family birthstone jewelry guide shows which formats suit softer stones.
Ready for a ring that keeps up with you? Browse our stackable birthstone rings in sapphire, ruby, emerald and more.
