February's birthstone is amethyst, and until about 1830 it was one of the five most valuable gems on earth — sold alongside diamond, ruby, emerald and sapphire, worn by cardinals and set in crowns.
Then somebody found Brazil. Enormous deposits came out of Rio Grande do Sul and Minas Gerais, the supply went from scarce to endless in a generation, and amethyst dropped out of the cardinal five and became the affordable purple stone it is today.
Nothing about the stone changed. Only the number of them changed. It is the clearest lesson in gemmology that rarity, not beauty, sets the price.
Purple is radiation damage
Amethyst is quartz — silicon dioxide, the most ordinary mineral in the crust, colourless in its pure form. The purple comes from a trace of iron sitting where a silicon atom should be, which does nothing on its own. It needs a second event: natural radiation from the surrounding rock, over geological time, knocking an electron loose and leaving a colour centre behind.
So the colour is a defect, produced by damage, held stable for millions of years. That is genuinely what purple quartz is.
Which is why it fades
Because the colour is a trapped electronic state rather than a chemical pigment, energy can undo it. Amethyst fades in strong sunlight. Not in an afternoon — but a stone left on a sunny windowsill for years will go pale, and it does not come back on its own.
This is the one piece of care advice that actually matters for the stone. Wear it, wash it, do not store it where the sun hits it.
Heat it and it becomes citrine
Take amethyst to somewhere around 400–500°C and the iron changes oxidation state. The purple goes, and yellow to orange arrives instead. The stone that comes out is citrine.
This is not a trick — it is the same mineral, and heated citrine is stable and permanent. But it is worth knowing that almost all citrine on the market is heated amethyst, because natural citrine is genuinely uncommon. February and November are, in a large number of shop windows, the same rough material at two different temperatures.
Ametrine — the two-tone purple-and-gold quartz — is a single crystal where part of it made that transition and part of it did not.
The name is a hangover cure
"Amethyst" comes from the Greek amethystos, "not drunk". The Greeks believed the stone protected the wearer from intoxication, and wine cups were carved from it — some argue partly so that water in a purple cup looked like wine, which is a more practical use of a gemstone than most.
The Roman writer Pliny records the belief and is sceptical about it, which is a useful reminder that stone meanings have always had sceptics contemporary with them. The association survives because it is a good story, not because anyone demonstrated it.
What good amethyst looks like
Colour does almost all the work in pricing. The most valued material is a deep purple with red or blue flashes — the trade calls the top grade "Siberian", which is now a colour description rather than a place, since almost none of it comes from Siberia.
Two things to look for. First, colour zoning: amethyst frequently grows in bands, and a badly cut stone shows a pale window on one side. A well-cut stone hides the zoning by orienting it. Second, saturation at small sizes — pale material is abundant and cheap, and there is no reason to pay for it.
Amethyst is 7 on the Mohs scale. That is hard enough for daily wear but soft enough to scuff over years on a ring worn constantly. It is a better everyday stone in earrings and pendants than in a ring you never take off.
What we make for February
Amethyst is the stone we make most of, so there is a real choice here rather than one option.
The Thing You Know is the plain statement of it — one amethyst, nothing else asking for attention. Night Amethyst sets the same stone against blackened rhodium, which drops the background out and makes the purple read darker than it is. Two Voices puts amethyst next to a green accent so each colour pushes the other forward.
For something larger: Winged Amethyst is a butterfly set, Purple Root is a branch ring and earrings, and Night Garden is the full three-piece.
The everyday version is Month in Colour: one baguette stone on a fine chain, solid 925 sterling silver plated in gold rather than plated brass. The February stone is purple. It is cubic zirconia cut to the birthstone colour, not amethyst. That is on the product page, not in the small print.
Everything is made after you order it, so allow up to ten days.
All twelve months, and what each stone actually is →
What amethyst has been used to mean →
A birthstone is a date, not a diagnosis. Nothing here treats, prevents or cures anything.