Example 1
- Month: 1
Garnet
January → garnet.
Birthstone calculator
From month number 1-12 you read a gem from a western jewelry-tradition list. The day of birth does not change the stone.
Here the stone comes only from the month number. This tool is for entertainment and learning, not fortune-telling or life advice. It does not replace personal, medical or financial decisions. Also try the zodiac sign, Chinese zodiac and moon phase.
Result
Enter a month (1-12) to see the birthstone.
How it works
A birthstone is a cultural mapping from calendar month to a gem. The list we use follows popular western tradition (including 20th-century jewelry charts).
Mapping is simple: month 1 → garnet, 2 → amethyst, 3 → aquamarine, 4 → diamond, 5 → emerald, 6 → pearl / moonstone.
Then: 7 → ruby, 8 → peridot, 9 → sapphire, 10 → opal / tourmaline, 11 → topaz / citrine, 12 → turquoise / zircon / tanzanite.
Some months have more than one accepted stone. We show them together because tradition is local and commercial, not a single “correct” law.
This is not a zodiac sign (day and month in the tropics) or a Chinese animal (year). It also does not describe the moon phase.
In practice the month stone is often a gift or jewelry motif. Treat the result as a cultural label, not a medical or magical property.
Other lists (historic British or regional ones) may use different names. Here we keep one clear 1-12 table.
A blank “Birth month” is an error, not zero. A typed zero can be a real value, but an empty field does not calculate. Commas and dots both parse.
If you wanted a different quantity than birthstone, open zodiac sign. This page stays on one question so the result card matches the formula label.
The metric/US switch relabels empty fields. It does not multiply a number you already typed. Mixing units in one box makes the result wrong no matter the formula.
The card usually shows two decimal places. That is display rounding, not a code and not a supplier rule. A blank field does not fake a zero.
Birthstone only uses what you type in the form. It does not talk to a store, a bank, or a gradebook. A refresh clears the fields.
Formula
stone = table[month], where month ∈ {1,…,12}.
No number reduction: this is a cultural lookup, not a physics formula.
How to use the calculator
- Enter a month number from 1 to 12.
- Click Calculate or wait for the live result.
- Leave a blank field blank: the calculator errors out and does not fake a zero.
- The metric/US switch relabels units and does not convert a number you already typed.
- Compare with tropical and Chinese signs from the same biography.
Suggested uses
- Quick month-stone check before a gift.
- Learn the popular 12-stone list with concrete months.
- Compare months in a family for fun.
- Start a set: birthstone + tropical sign + Chinese animal.
- Draft a note about regional list differences.
- Verify that a hand table lookup matches the tool.
Examples
Example 2
- Month: 3
Aquamarine
March → aquamarine.
Example 3
- Month: 5
Emerald
May → emerald.
Example 4
- Month: 7
Ruby
July → ruby.
Example 5
- Month: 9
Sapphire
September → sapphire.
Example 6
- Month: 12
Turquoise / zircon / tanzanite
December has several popular variants.
Example 7
- Birth month: 1
Result on the card after fill
What is birthstone calculator of 1?
Example 8
- Birth month: 2
Result on the card after fill
What is birthstone calculator of 2?
Related calculators
Frequently asked questions
What is a birthstone?
A traditional gem label for the birth month. It is a cultural tag, not a geological test of a person.
Where does this list come from?
From popular western tradition used in jewelry and guidebooks. Local lists can differ.
Why do some months have several stones?
Because tradition and markets allow variants. We show them together instead of forcing one “canonical” pick.
Does the birth day change the stone?
Not in this calculator. Only the month number 1-12 matters.
How is Birthstone calculator different from Zodiac sign?
A tropical sign depends on day and month in a Sun table. The birthstone depends only on the month.
Is this fortune-telling or a healing claim?
No. The calculator is entertainment and education. It does not replace medical, jewelry or life advice.
What range can I enter?
A whole number from 1 to 12. Values outside that range are rejected.
Is June pearl or moonstone?
Both are often accepted. That is why we show “pearl / moonstone”.
Which stone is January, and which is March in this table?
1 is garnet. 3 is aquamarine. June is pearl or moonstone on other lists; here each month has one entry.
Is a blank month treated as January and garnet?
No. Type 1-12. Zero is not January. Blank is a validation error.