March birthstone

March's main stone — the aquamarine

Pale is the trap with aquamarine. Under a jeweller's lighting nearly every stone looks convincingly blue; carry the same one to a window and half of them turn into faintly tinted water. Colour here concentrates with size, so a two-carat stone of middling material reads far bluer than half a carat cut from the same rough. That makes March one of the few months where buying bigger genuinely buys more, and explains why tiny aquamarines in cluster rings so often look like nothing at all.

Almost every aquamarine on sale has been through an oven. Straight out of the ground the crystals lean green-yellow; a few hours at four hundred-odd degrees drives that component off and leaves the clean blue the market wants. The change is permanent, the trade treats it as routine, and hardly anyone puts it on the ticket. Nothing dishonest is going on — but if you would rather have the seawater green the crystal came out with, you will have to ask for untreated material by name, because it will not be offered.

March asks less of a budget than the months on either side of it. Aquamarine grows in large, clean crystals, so per carat it costs a fraction of sapphire and a flawless five-carat stone is ordinary rather than remarkable — size, for once, is the affordable variable. Spend on colour instead. The gap between a stone that reads blue from across a room and one that reads as tinted water is worth far more than two extra carats, and it is the only difference anybody will actually see.

The other stones listed for March

Bloodstone is March's other stone and it is the opposite of the first in every way: opaque dark green chalcedony spattered with red iron oxide, the colour of a fir wood after rain. British lists kept it for March long after American ones switched to aquamarine, which is how an English grandmother and an American catalogue end up disagreeing about the same birthday. Most of it comes from the Deccan basalts in India, it costs very little, and it has always been a carver's stone — signet rings, seals, heavy cabochons rather than faceted sparkle.

Buying it needs one eye open: bloodstone on a cheap counter is frequently dyed jasper, and the giveaway is spotting that looks too regular or too bright a red, where the real thing scatters dull flecks unevenly. The name deserves a second's thought as well. It came from a medieval belief about staunching wounds, and that belief is the one part of the stone's story that has not survived — it does nothing for anybody's blood, and a person who is actually ill needs a doctor rather than a green pebble. As for which of the two stones March really owns, there is no referee: the astrological chart running alongside gives the month Pisces stones through 20 March and Aries from the 21st, and none of the four lists outranks the others.

What the aquamarine actually is

Aquamarine is beryl — a beryllium aluminium silicate — coloured by iron sitting inside the crystal structure. Swap the trace element and the same mineral turns up green as emerald, pink as morganite, yellow as heliodor. It forms in pegmatites, the coarse veins where the last water-rich portion of a granite melt crystallises slowly, and that slow growth is the reason aquamarine comes out so large and so clean: metre-long columns are on record, and cut stones above ten carats are unremarkable.

The lookalike to know about is blue topaz. Nearly all of it is colourless topaz that has been irradiated and heated into a blue no aquamarine ever reaches — brighter, almost electric, and far cheaper, which is precisely how it ends up on the wrong label. Two rough checks help: topaz of the same size feels noticeably heavier in the palm, and aquamarine shifts visibly between blue and near-colourless as you turn it, a habit topaz shows much more weakly. Trade names deserve the same scepticism. Santa Maria began as a place — the Santa Maria de Itabira workings in Brazil, famous for an unusually deep blue — but the phrase came loose from the mine long ago and now grades depth of colour, applied to strong Mozambican and Nigerian material as readily as Brazilian. It describes the stone in front of you and promises nothing about where it was dug.

The March stone as a gift

A March present rewards a little nerve about size. Small pale aquamarines vanish against skin, so the same money spent on one larger stone, or on deeper-coloured Mozambique material, gives something that actually reads as blue from across a room. It handles daily wear without complaint, being a hard stone, though it dislikes a sharp knock on an edge — a ring that shelters the girdle will outlive a tall solitaire.

For someone born in the first half of the month who prefers green to blue, bloodstone is a legitimate choice and costs almost nothing; a carved cabochon in silver looks far more considered than its price suggests. It also solves the problem aquamarine has. A flat-topped cabochon or a signet takes the knocks that chip a faceted edge, which makes it the stone for somebody who works with their hands and never remembers to take a ring off.

Where the month chart came from

Nothing in geology or astronomy ties a mineral to a page of the calendar. The chart everyone quotes was agreed by American jewellers in 1912, in Kansas City, so that shops across the country would sell one list rather than twelve. It has been edited since: alexandrite, citrine, tourmaline and zircon were added in 1952, and tanzanite joined December as late as 2002 — thirty-five years after the stone was first dug up in Tanzania.

So when two shops give you two different stones, neither of them is lying. British lists keep bloodstone for March where American ones print aquamarine. June carries pearl from the old custom and moonstone plus alexandrite from the newer one. Read any of these charts as a custom with a paper trail — a dated commercial agreement — and not as a fact about the person born that month.

Month or star sign: two different lists

The month stone and the zodiac stone belong to different traditions: one is a jewellers' chart, the other is astrology, where the stone is derived from the ruling planet and the element. Two signs fall inside March: Pisces stones (through March 20) and Aries stones (from March 21). We do not repeat the astrology here — that reading lives on the sign pages.

At a glance

Frequently asked questions

The month-by-month chart is a 20th-century jewellery custom, not science: no link between a mineral and a birth date has ever been demonstrated. Stones do not heal and do not steer events — health questions belong with a doctor, not with a pendant. The stone images on this page are generated illustrations, not photographs of particular specimens.