October Birthstone: Opal

October's stone and the trouble with rainbows

Opal is October's birthstone, and no other stone on the list throws its color out at an angle instead of simply containing it. A good opal throws red, green and blue out of a pale background depending on the angle, and the older sources treated that shifting quality as the stone's whole meaning: play, change, and the refusal to sit still.

Tourmaline is the month's alternative, and it is the only stone that comes in more colors than opal does — pink, green, blue, black, and in some crystals several at once. The two alternatives for October are therefore both about variety, which no other month can say.

The recorded qualities are creativity, inspiration, hope and protection. The first two follow obviously from a stone that looks different every time it moves. The last one is older than the others: opal was carried against misfortune long before anyone called it a birthstone, and its reputation as an unlucky stone is a nineteenth-century invention that the earlier sources would not have recognized.

Why opal was called unlucky

The bad reputation is recent and traceable. A bestselling novel published in the 1820s gave its heroine an opal that brought disaster, and the association stuck hard enough that the stone trade spent a century trying to reverse it. Before that, the sources are consistent in the opposite direction: opal was worn for protection and for hope, and the Romans ranked it second only to emerald.

What the older lists valued was the stone's honesty about change. An opal does not look the same from two angles, and the old books read that as an honest emblem of change — a stone for people whose circumstances keep moving.

Tourmaline carries a quieter set of ideas. It was traditionally given as a stone of friendship and worn for steadiness, and it has the practical advantage of coming in colors that match almost anything, which is why it appears so often in the older amulet lists.

Neither stone is described as producing inspiration. Both are described as companions for people already working on something.

October's signs, one of which shares the stone

Libra fills most of October, and its recorded stone is opal — the same one the month claims. The Libra page carries that portrait: cardinal air, ruled by Venus, diplomatic, aesthetic, weighing a room without being asked to.

Scorpio begins as the month turns toward its end, and its recorded stone is topaz — the golden stone of November. The Scorpio page sets out the rest: fixed water, ruled by Mars and Pluto, private, intense, patient to a fault.

So October follows the pattern that half the year follows: agreement for the earlier sign, separation for the later one. Birthdays in the first three weeks get one shimmering answer; birthdays after that hold an opal for the date and a golden stone for the sun. A longer treatment of both stones sits on this site — the October essay — which explains why the month ended up with two that share almost nothing.

Handling an opal

Opal is the most fragile birthstone on the calendar. It is a hydrated mineral — five to ten percent of it is water — and that water is why it can craze and crack if it dries out or is heated. It is also soft enough to scratch, sensitive to acids, and unhappily easy to destroy with a cleaning machine. Old jewelers advised wearing opal often and storing it in a way that does not let it dry completely.

Tourmaline is harder and considerably more forgiving, needing only the ordinary care of a gem in the seven to seven-and-a-half range. The trade-off is that tourmaline shows wear at the edges rather than the surface, which is why old stones often look slightly rounded.

Looking down the calendar, September holds sapphire and November holds topaz — so October's shifting color sits between the year's steadiest blue and its warmest gold.