All twelve months with both lists side by side — modern and traditional. They agree more often than the disagreement gets talked about: 2 months out of 12 name a different stone.
| Month | Modern | Traditional | Colour | Zodiac |
|---|---|---|---|---|
| January | Garnet | Garnet | Deep red | Capricorn, Aquarius |
| February | Amethyst | Amethyst | Purple | Aquarius, Pisces |
| March | Aquamarine | Bloodstone | Pale blue to sea green | Pisces, Aries |
| April | Diamond | Diamond | Colourless | Aries, Taurus |
| May | Emerald | Emerald | Green | Taurus, Gemini |
| June | Pearl, Moonstone, Alexandrite | Pearl | White, cream and colour-shifting | Gemini, Cancer |
| July | Ruby | Ruby | Red | Cancer, Leo |
| August | Peridot, Spinel | Sardonyx | Yellow-green | Leo, Virgo |
| September | Sapphire | Sapphire | Deep blue | Virgo, Libra |
| October | Opal, Tourmaline | Opal | Iridescent and multicoloured | Libra, Scorpio |
| November | Topaz, Citrine | Topaz | Yellow to amber | Scorpio, Sagittarius |
| December | Turquoise, Zircon, Tanzanite | Turquoise | Blue to blue-violet | Sagittarius, Capricorn |
Highlighted cells are the months where the two systems name different stones.
The modern list is younger than most people assume. American jewellers standardised it in 1912 through their national association, and it has been amended since — tanzanite was added to December in 2002, more than eighty years after the original list, and spinel to August in 2016. So a birthstone can be a twentieth-century commercial decision rather than an ancient assignment.
The traditional list is older and varies by source, because it was never centrally agreed. Most months survived standardisation unchanged — only 2 name a different stone, and in both cases the older one was displaced by something easier to supply: aquamarine replaced bloodstone in March, peridot replaced sardonyx in August. Where they differ, a jeweller shows the modern stone, since that is what the trade adopted.
There is also a third system entirely, running by zodiac sign rather than calendar month, which is older than both. Birthstones by zodiac sign →
Household dust contains quartz, which sits at 7 on the Mohs scale, so stones softer than that slowly scratch and dull when worn every day. For an engagement or everyday ring, hardness matters more than tradition.
| Month | Stone | Mohs hardness | Everyday ring? |
|---|---|---|---|
| January | Garnet | 6.5–7.5 | With care |
| February | Amethyst | 7 | With care |
| March | Aquamarine | 7.5–8 | Yes |
| April | Diamond | 10 | Yes |
| May | Emerald | 7.5–8 | Yes |
| June | Pearl | 2.5–4.5 | Better in earrings or pendants |
| June | Moonstone | 6–6.5 | Better in earrings or pendants |
| June | Alexandrite | 8.5 | Yes |
| July | Ruby | 9 | Yes |
| August | Peridot | 6.5–7 | With care |
| August | Spinel | 8 | Yes |
| September | Sapphire | 9 | Yes |
| October | Opal | 5.5–6.5 | Better in earrings or pendants |
| October | Tourmaline | 7–7.5 | With care |
| November | Topaz | 8 | Yes |
| November | Citrine | 7 | With care |
| December | Turquoise | 5–6 | Better in earrings or pendants |
| December | Zircon | 6–7.5 | Better in earrings or pendants |
| December | Tanzanite | 6–7 | Better in earrings or pendants |
Aquamarine (March), Diamond (April), Emerald (May), Alexandrite (June), Ruby (July), Spinel (August), Sapphire (September), Topaz (November). Diamond, ruby and sapphire are the classic choices; spinel and alexandrite are harder than most people expect. Hardness is not toughness, though: emerald is full of tiny fractures and topaz splits along a cleavage plane, so both still need a protective setting.
Pearl (June), Moonstone (June), Opal (October), Turquoise (December), Zircon (December), Tanzanite (December). Pearls and opals react to perfume, heat and dry air; turquoise is porous and changes colour with skin oils.
Where a month has a soft modern stone, the alternative stone is often the practical pick — spinel instead of peridot for August, topaz instead of citrine for November. Choosing birthstone jewellery →