Quick answer
Birthstones are month-to-stone mappings, not a single official list. The 1912 American standard gave each month one stone; older traditions and later marketing added alternatives, so June, October and November now carry two. Pick the month, and the tool returns the traditional stone, what modern lists add, the hardness, whether it survives an everyday ring, and the cheaper stone that carries the same meaning.
The practical question with a birthstone is never the meaning, it is whether the piece survives being worn. A pearl and a sapphire are both birthstones; one is a 2.5 on the Mohs scale and the other is a 9. This tool puts that difference in front of you before you buy.
All twelve months, with hardness and alternatives
This is the whole chart in one table, with the two things a birthstone gift usually gets wrong: choosing a soft stone for a ring, and paying traditional-stone prices when the alternative carries the same meaning. The last column names the cheaper stone for each month where one exists.
| Month | Traditional stone | Modern additions | Mohs | Everyday ring? | Budget alternative |
|---|---|---|---|---|---|
| January | Garnet | None | 6.5-7.5 | Yes | None needed |
| February | Amethyst | None | 7-7 | Yes | None needed |
| March | Aquamarine | None | 7.5-8 | Yes | None needed |
| April | Diamond | None | 7-7 | Yes | Diamond is the traditional stone |
| May | Emerald | None | 7.5-8 | No - pendant instead | Green aventurine |
| June | Pearl | Moonstone | 6-6.5 | No - pendant instead | Pearl is the traditional stone |
| July | Ruby | None | 9-9 | Yes | Red garnet |
| August | Peridot | Spinel | 6.5-7 | No - pendant instead | None needed |
| September | Sapphire | None | 9-9 | Yes | Lapis lazuli |
| October | Opal | Pink tourmaline | 5.5-6.5 | No - pendant instead | None needed |
| November | Topaz | Citrine | 8-8 | Yes | None needed |
| December | Turquoise | Tanzanite, Blue zircon | 5-6 | No - pendant instead | None needed |
Why three months have two stones
The 1912 standard, set by the American National Retail Jewelers Association, gave each month exactly one stone. Everything since has been addition: pearl gained moonstone, opal gained tourmaline, topaz gained citrine, peridot gained spinel, and December picked up tanzanite and blue zircon after tanzanite was discovered in 1967. There is no single official list, and different countries and jewelers use different versions. That is worth knowing before you let anyone tell you your birthstone is wrong.
Matching the stone to the piece
A birthstone is a constraint you did not choose, which makes the form the thing you can still control. Anything at Mohs 7 or above survives a daily ring. Below that, move the stone to a pendant, an earring or a brooch, where it will not meet doors and keys. This is the one place where the traditional stone is often the wrong choice: an emerald or an opal in a daily ring will not last, however good the stone is. Our birthstone match guide walks through the form decision, and the full birthstone chart covers the meanings.
Sources
- Mohs hardness scale as published in mineralogy references; values cross-checked against species data maintained by Mindat, the mineral database of the Hudson Institute of Mineralogy.
- Treatment and disclosure practice follows the terminology used by the Gemological Institute of America in its gem-treatment guidance.
- Stone identification limits: hardness testing, specific gravity and refractive index are the standard tests, described in the GIA Gem Encyclopedia.
- The 1912 birthstone standard is attributed to the American National Retail Jewelers Association; modern additions (moonstone, spinel, citrine, tourmaline, tanzanite, zircon) are documented in the GIA Gem Encyclopedia.
Disclaimer
This is reference information for buying, wearing and caring for stones, not a laboratory identification and not medical advice. Hardness values follow standard mineralogy and a given piece can behave differently if it is treated, fractured or unusually thin. For anything you intend to put in your mouth, on broken skin or in a container of drinking water, treat a jeweller's or a mineralogist's in-person assessment as the only reliable answer.
