Birthstone calculator

Type the birth month as a number from 1 to 12. May (5) is emerald. January (1) is garnet. December shows turquoise, zircon, and tanzanite together. Day and year do not enter.

A month label, entertainment and tradition, not a reading. Sign: zodiac sign. Year: Chinese zodiac. Article: Birthstone.

Input

Result

Enter a month (1-12) to see the birthstone.

How it works

A birthstone is a cultural mapping from month to gem. The list follows popular western tradition, including 20th-century jewelry charts. 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. March is aquamarine, July ruby, September sapphire. Some months carry more than one accepted stone, because tradition is local and commercial.

A gem mapped to the birth month. It does not describe moon phase. The day of the month does not move the row: 5 May and 31 May are the same emerald.

One field: month 1-12. Click Calculate. Other lists (historic British, regional) can differ in names. Here one table, so the result is repeatable.

In practice the stone is often a gift motif. Treat it as a cultural label, not a medical or magical property.

Compare the tropical sign from day and month and the animal from the year if you are stacking a set from the same biography.

Formula

stone = table[month], where month ∈ {1,…,12}.

No number reduction: this is a cultural lookup, not a physics formula.

How to use

  1. Type the birth month as a number from 1 to 12. January is 1, December is 12.
  2. Click Calculate. The result is the table row for that month.
  3. Check 5: emerald. Check 1: garnet.
  4. For December (12) you will see several names at once: turquoise, zircon, tanzanite.
  5. Compare the tropical sign and the Chinese zodiac from the same biography. Those are other date axes.

A stone from month 1-12

May (5) is emerald. January (1) is garnet. December shows turquoise, zircon, and tanzanite together. Day and year drop out.

emerald
Month 5. One row on a jeweler list. The birthday day does not change the stone.
garnet
Month 1. March is aquamarine, July ruby, September sapphire. A 1-12 list, not a reading.

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 1

  • Month: 1

Garnet

January → garnet.

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.

Related calculators

Zodiac sign

Pick a birth date.

Use calculator →

Chinese zodiac

Chinese zodiac: a birth year.

Use calculator →

Moon phase

Pick a date.

Use calculator →

Biorhythms

From birth date to a chosen day you compute three sine waves: 23-day physical, 28-day emotional, 33-day intellectual.

Use calculator →

All esoteric calculators

Frequently asked questions

What stone is May?

Emerald. Month 5 on this jewelry list is a single stone. Day and year do not change it.

What about January and March?

January (1) is garnet. March (3) is aquamarine. Only the month number picks the row.

Is this a scientific forecast?

No. It is a cultural label from a 1-12 table. Not a geological test of a person.

Why does December have three names?

Tradition and the market allow variants. We show turquoise, zircon, and tanzanite together, without picking one “true” stone.

Does the birthday change the stone?

No. Only the month number. 5 May and 31 May are emerald.

How is this different from the zodiac sign?

The sign uses day and month in the tropics. The stone uses the month number alone.

What about July and September?

July (7) is ruby. September (9) is sapphire. Same 1-12 table, not a forecast.

Is June only pearl?

On this list June is pearl / moonstone. Two accepted variants in one row.

Where does this list come from?

Popular western tradition used in jewelry. Local lists can differ.

Is a blank field January and garnet?

No. Without a month there is no row. Type a number from 1 to 12.

Knowledge sources

The calculator reads a date or a tradition table. This is not fortune-telling, not an astrologer’s chart and not a diagnosis.

Page updated in 2026.