The list you are about to read is younger than almost everyone assumes. Not ancient, not handed down — assembled by a trade body in Kansas City in 1912, revised in 1952, and revised again in 2002 and 2016 when somebody wanted to sell tanzanite and spinel. It is a retail document. That does not make it worthless. It makes it a hundred and fourteen years old, which is long enough for a great many people to have been given a stone on a birthday and kept it.
What follows is the modern list, month by month: what the stone actually is, where it comes from, and — where we carry something in that colour — what we would put on a person born then. Nine of the months now have a longer file of their own, linked under each entry.
January — Garnet
Named after a fruit. Granatum, the pomegranate: split one open and the reason is obvious, rows of dark red seeds packed under a hard skin, which is close to what garnet-bearing rock looks like when you break it.
Garnet is not one mineral but a family of them, which is why it turns up in colours nobody expects — green tsavorite, orange spessartine, the raspberry rhodolite we use most. The red is the one the list means. It went into Anglo-Saxon graves, Roman signet rings and Bohemian brooches, and for most of that history it was the stone people took with them when they were travelling at night.
The full file on January and garnet →
January pieces →
February — Amethyst
A-methystos: not drunken. The Greeks cut wine cups from it because they thought the stone would keep the drinker answerable, which tells you more about Greek dinner parties than about quartz.
For nine hundred years amethyst was priced beside ruby and emerald. Then in the eighteenth century enormous deposits turned up in Brazil, supply collapsed, and the price went with it. Nothing about the stone changed — only how much of it there was. It is worth remembering the next time somebody tells you a gem is valuable because of what it is.
The full file on February and amethyst →
February pieces →
March — Aquamarine
Beryl, the same mineral as emerald, coloured by iron instead of chromium. Sailors carried it because it was the colour of the water they wanted to see rather than the water they were in.
We do not carry aquamarine, and we are not going to pretend otherwise. Sky blue topaz sits closest to it — the same pale, cool, nearly transparent blue — and it is a different mineral and a different stone. What we wear in its place →
April — Diamond
Carbon, arranged so that every atom is bonded to four others in a tetrahedron, which is why it is the hardest natural substance and why it took until the fifteenth century for anyone to work out how to cut one properly.
The idea that April means diamond is a twentieth-century advertising achievement rather than a mineralogical one. We set moissanite instead — silicon carbide, first found in a meteorite crater in Arizona in 1893 and mistaken for diamond by the man who found it. It breaks more colour out of the same light than diamond does; jewellers call that fire. Moissanite against diamond, measured →
The moissanite pieces →
May — Emerald
Beryl again, chromium this time. Emerald is famously included — the internal fractures have their own French name, jardin, the garden — and a completely clean one should make you suspicious rather than pleased.
We carry green in chrome diopside and green agate rather than emerald. Chrome diopside comes almost entirely out of Yakutia, in the short window each year when the ground is frozen hard enough to work, and reads nearly black in low light before turning emerald under a lamp.
June — Pearl, Moonstone, Alexandrite
Three, because June could not settle. Moonstone is the one we make.
The blue in moonstone is not pigment. It is light bouncing off microscopic layers of two feldspars stacked inside the stone — adularescence — which is why it drifts as you turn your hand and never lands in the same place twice. There is nothing in the stone that is blue.
Alexandrite is the strangest of the three: green by daylight, red under a lamp, because chromium in the crystal transmits two windows of light and daylight and tungsten weight them differently.
The full file on June's three stones →
The longer file on moonstone → · The alexandrite ring →
July — Ruby
Corundum with roughly one aluminium atom in a hundred swapped for chromium. Take the chromium out and put in iron and titanium and you have sapphire. That single substitution is the entire difference between the two most famous coloured stones in the world.
Our star ruby is lab-grown and the page says so. The six-rayed star is asterism — light scattering off needle inclusions arranged along three axes — and it only shows under a single light source, so you have to hold it right to find it.
The full file on July and ruby →
The star ruby ring →
August — Peridot
Olivine. The one gemstone that comes in a single colour, because the green is not an impurity but the mineral itself.
The Romans mined it at night on Zabargad, a guarded island in the Red Sea, and shipped it out as treasure — night mining because the stone is easier to spot by lamplight than in desert glare. Some peridot on earth arrived inside pallasite meteorites, which is the only gem you can say that about with a straight face.
The full file on August and peridot →
The peridot piece →
September — Sapphire
Second-hardest thing on earth, and it decided to be the colour of the sky. Bishops' rings and travellers' clasps, for exactly that reason.
Almost all sapphire on the market is heat-treated, and that has been normal for a very long time. What matters is whether the seller tells you. We name every treatment on the product page — the diffusion sapphire set is labelled diffusion sapphire, not sapphire.
The full file on September and sapphire →
The sapphire pieces →
October — Opal, Tourmaline
Opal is not a crystal at all. It is microscopic spheres of silica stacked in a lattice with water still held between them, and its fire is light diffracting off that stack. Change the size of the spheres and you change the colour that comes back out. Because of the water it can craze if it dries out, which is why opal is the one stone we ask you not to leave on a windowsill.
Most of the Zodiac Circle is set with African opal.
The full file on October's two stones →
The opal pieces →
November — Topaz, Citrine
Topaz has been carrying somebody else's name for two thousand years: the Roman topazos was almost certainly peridot from Zabargad, and by the time anyone sorted out the mineralogy the name had stuck to the wrong stone.
Citrine was the merchant's stone, kept where money was actually counted — cash boxes, ledger drawers. Most citrine sold today is heated amethyst, and there is a way to tell: natural citrine is evenly coloured, heated amethyst usually holds a reddish or smoky cast near the base.
The full file on November's two stones →
How to tell one from the other →
December — Turquoise, Tanzanite, Zircon
Turquoise is the oldest of all of them. It was mined in Sinai before the pyramids, strung on Egyptian mummies, and traded across the Silk Road for six thousand years — and the name is French, pierre turquoise, the Turkish stone, because that is the route it arrived by rather than the ground it came out of.
Tanzanite was added to the list in 2002, thirty-five years after it was discovered, by a trade association. It comes from one hill in Tanzania and nowhere else on earth.
The full file on December's four stones →
The longer file on turquoise →
If you want the colour rather than the mineral
There is an honest gap between the two things people mean by “my birthstone”. Some want the actual mineral — natural garnet, natural amethyst, cut and set. Others want the colour of their month on a chain, at a price that makes sense as a gift.
We make both, and we label which is which. The Month in Colour necklace is gold-plated solid silver set with cubic zirconia cut to each month's colour — it is not the natural stone, and the page says so in the first line. The natural-stone pieces sit in the stone collections.
Neither is the more honest option. Pretending one is the other is the dishonest one.
Nothing on this page treats, prevents or cures anything. These are stones, and the meanings attached to them are history rather than medicine — we have written separately about where those meanings actually come from.