Birthstones by zodiac sign
The older of the two systems — running by sign rather than calendar month, which is why it often disagrees with the one your jeweller uses.
| Sign | Dates | Element | Stones |
|---|---|---|---|
| Aries | March 21 – April 19 | Fire | Diamond, Bloodstone |
| Taurus | April 20 – May 20 | Earth | Emerald, Sapphire |
| Gemini | May 21 – June 20 | Air | Pearl, Agate |
| Cancer | June 21 – July 22 | Water | Ruby, Moonstone |
| Leo | July 23 – August 22 | Fire | Peridot, Onyx |
| Virgo | August 23 – September 22 | Earth | Sapphire, Carnelian |
| Libra | September 23 – October 22 | Air | Opal, Peridot |
| Scorpio | October 23 – November 21 | Water | Topaz, Obsidian |
| Sagittarius | November 22 – December 21 | Fire | Turquoise, Topaz |
| Capricorn | December 22 – January 19 | Earth | Garnet, Ruby |
| Aquarius | January 20 – February 18 | Air | Amethyst, Garnet |
| Pisces | February 19 – March 20 | Water | Aquamarine, Amethyst |
Why this list is older
The zodiac assignment came first. First-century writers, notably Josephus, connected the twelve stones of the high priest's breastplate in Exodus to the twelve signs — and the original practice was to own all twelve, wearing each during the weeks it governed.
Wearing only the stone of your own birth is a much later idea, and the monthly calendar version younger still. When the two lists disagree, it is not that one is wrong: they are answering slightly different questions.
Which one applies to you
Zodiac signs cross month boundaries, so the day matters. Born on 5 October, you get opal from both systems and there is no conflict. Born on 28 October, the calendar gives you October's opal while the zodiac gives you Scorpio's topaz.
Plenty of people wear both. Nothing in either tradition requires choosing.
Why the zodiac and monthly lists never line up
Zodiac signs follow the sun's position on the ecliptic, not the calendar. Every sign therefore opens in the middle of one month and closes in the middle of the next, and the split is never even — Gemini gets 11 days of May against 20 of June, Leo 9 days of July against 22 of August.
The practical consequence is that two people with the same sign, born three weeks apart, are sold different stones — because a jeweller works from the calendar month, which the trade standardised in 1912, while the zodiac list is older and runs on a different clock entirely.
Four stones exist only in the zodiac system and appear in no month at all: agate, onyx, carnelian and obsidian. Those are the places where the older tradition kept something the trade dropped. The monthly list →
Whether your stone survives being worn
The Mohs scale runs 1 to 10 and measures one thing only: what scratches what. It is not a scale of toughness — diamond sits at 10 and still cleaves if struck at the right angle. What it predicts is wear.
The number that matters is 7, because ordinary household dust contains quartz, which sits exactly there. Anything below 7 is being sanded every day it is worn: opal at 5.5–6.5, obsidian at 5–5.5, pearl softest of all at 2.5–4.5. Those belong in earrings and pendants, which do not meet surfaces. Sapphire and ruby at 9, diamond at 10, take daily wear in a ring indefinitely.
This is the part a birthstone list never mentions, and it decides whether a gift is still intact in ten years.