THE STORY OF BIRTHSTONES

An old idea,
a 1912 list.

Twelve months, twelve stones. The idea is old; the list is not.

Twelve small polished gemstones in different colours laid in a neat row on pale linen, from deep red to violet, green, blue and milky white — AI-generated image, not a photograph of a real person or place.

Old lore, new lists
Lists differ by country
Some months have three
A tradition still being edited

Ancient writers linked twelve stones to twelve months, but the custom of wearing your own month's stone came much later, and the list most people use today was agreed by jewellers in 1912 and has been edited since.

Updated 18 October 2026

THE SHORT ANSWER

Jewellers wrote it,
and keep revising it.

The lore goes back centuries.
The month-by-month list is a modern standard.

THE LIST

Agreed in Kansas City

In August 1912 the American National Association of Jewelers adopted a standard list. The gem writer George F. Kunz noted it moved ruby to July and turquoise to December.

Pick a month

MISTAKEN IDENTITY

The ruby that is a spinel

GIA says the roughly 170 ct Black Prince's "ruby" in the Imperial State Crown is really a red spinel. Spinel joined August's US list in 2016.

See the numbers

FROM THE DEEP

August's lava gem

Peridot, August's modern stone, can be found in hardened lava from Earth's mantle and even in meteorites, according to GIA.

Read a list

PICK A MONTH

How much has
your month changed?

Pick a month with a story to see how its stones have shifted since the 1912 list. The bar shows how much the list for that month has changed.

Lists compared: the 1912 Kansas City list as printed by Kunz (1913), today's US list as given by GIA, and the UK National Association of Goldsmiths list as archived in 2007.

Month check

Choose a monthJulyOctoberJuneAugustDecember

JulyRuby, since 1912

The 1912 list gave July the ruby, swapping it with turquoise. Kunz thought warm red suited winter better, but the ruby has stayed July's stone.

OctoberOpal (and tourmaline)

1912 gave opal, with tourmaline as the alternate. The UK list archived in 2007 shows opal alone; the US list keeps both.

JuneNow three stones

1912 gave pearl, with moonstone as the alternate. Alexandrite was added later, and GIA now lists pearl, alexandrite and moonstone.

AugustOrder flipped, one added

1912 put sardonyx first and peridot second. Today peridot leads, sardonyx is the original stone and spinel was added in the US in 2016.

DecemberThree, with a newcomer

1912 gave turquoise with lapis lazuli. The US now lists turquoise, zircon and tanzanite, added in 2002; the UK list puts tanzanite first.

Sources: G. F. Kunz, The Curious Lore of Precious Stones (1913); GIA birthstone pages; National Association of Goldsmiths list (archived 2007); Wikipedia, Birthstone.

TWO NUMBERS WORTH KNOWING

Younger than it looks,
and still growing.

One date for the standard list,
one count of how crowded it has become.

1912

Year US jewellers adopted a month list

The National Association of Jewelers approved the list at its meeting in Kansas City in August 1912. Kunz, writing a year later, said it could scarcely be called a satisfactory answer.

THE STANDARD LIST · KUNZ 1913

3 months

Months with three birthstones

GIA says June, August and December each have three birthstones. In the 1912 list, no month had more than two.

CROWDED MONTHS · GIA

Britain's National Association of Goldsmiths drew up its own standard list in 1937, which is why UK and US charts do not always match.

Small yellowish-green peridot crystals embedded in a rough piece of dark volcanic rock — AI-generated image, not a photograph of a real person or place.

READING A BIRTHSTONE CHART

Four things to check
on any chart.

Birthstone charts online disagree more than you might expect. These checks explain most of the differences.

Which country's list?
US charts follow the jewellers' list; UK charts often follow the National Association of Goldsmiths, which differs for months such as December.
Which year?
Stones have been added over time: alexandrite and zircon after 1912, tanzanite in 2002, spinel in 2016.
Main stone or alternate?
Many months list a main stone and an alternate, and the order has flipped for some, such as August.
Month, star sign or weekday?
There are separate traditions linking stones to zodiac signs and even to days of the week. Check which one a chart shows.

WHERE THE IDEA BEGAN

Twelve stones,
many translations.

Kunz traced the idea to old lists of twelve stones, and to writers such as Josephus in the first century who linked them to the months and the zodiac. Translations of the old stone names vary so much that the lists do not line up neatly.

He found no sign of people wearing a single birth-month stone until much later, probably in Poland in the eighteenth century; a writer in 1762 suggested Germany. Wikipedia notes GIA dates the start to Germany in the 1560s.

A deep red faceted gemstone beside a smaller pink one on a jeweller's soft grey tray, with a plain brass magnifying loupe — AI-generated image, not a photograph of a real person or place.

Questions

Questions people ask

Who decides the birthstones?

Nobody official. In the US, jewellers' trade bodies set and update the list, starting in Kansas City in 1912. In the UK, the National Association of Goldsmiths made its own list in 1937.

Why does my month have more than one stone?

Lists often give a main stone and an alternate, and new stones have been added. GIA says June, August and December now have three each.

Is December turquoise or tanzanite?

Both appear. The 1912 list gave turquoise; tanzanite was added in the US in 2002 alongside zircon, and the archived UK list puts tanzanite first, with turquoise as the alternate.

Is the August birthstone peridot or sardonyx?

Both, plus spinel. GIA calls sardonyx the original August stone; the 1912 list made sardonyx the main stone and peridot the alternate, and peridot now usually comes first.

Are birthstones ancient?

The link between twelve stones and twelve months is old, but Kunz found the custom of wearing your own birth-month stone appeared much later, and the standard modern list dates from 1912.

An old idea,
a 1912 list.