January's birthstone is garnet, and garnet is not a stone. It is a family of at least six different minerals that happen to share a crystal structure, and the dark red one everybody pictures is the cheapest and least interesting member of it.
Some garnets are green and rarer than emerald. One changes colour under different light. One is orange and fluorescent. They are all correctly called garnet, and a shop that says "garnet" and means only red is telling you less than half of it.
Six minerals, one name
Garnets share a formula — three atoms of one metal, two of another, three silicate groups — and swap which metals fill those places. Change the metals and you change the colour, the hardness and the price.
- Almandine — iron. Deep red to brownish red. The common one, and the one in most Victorian jewellery.
- Pyrope — magnesium. Bright, slightly purplish red. The Bohemian garnet of the 1800s.
- Rhodolite — a natural blend of pyrope and almandine. Raspberry to violet-red, brighter and cleaner than either parent.
- Spessartine — manganese. Orange to mandarin. Genuinely uncommon in fine colour.
- Grossular — calcium and aluminium. Colourless to green; the vivid green form is tsavorite, and fine tsavorite outprices most emerald per carat.
- Andradite — calcium and iron. The green form is demantoid, which disperses light more strongly than diamond does.
Most stones sold as garnet sit somewhere on the line between two of these, because in the ground they blend continuously rather than sorting themselves into named boxes.
The best thing about garnet
Garnet is essentially never treated.
That sentence does not apply to many gemstones. Sapphire is routinely heated. Blue topaz is irradiated. Most citrine is heated amethyst. Emerald is oiled almost as a rule. Garnet does not respond usefully to heat, so nobody bothers, and what you buy is what came out of the ground.
If untreated matters to you — and for some people it genuinely does — garnet is the easiest honest answer in the entire calendar.
The one that changes colour
Colour-change garnet, mostly from Madagascar and East Africa, is a blend that absorbs light in a narrow band, so it reads blue-green in daylight and red or purple under incandescent light. It is the same mechanism that makes alexandrite do it, in a completely unrelated mineral. Some of the strongest colour-change material on earth is garnet, and almost nobody knows it.
Where the name comes from
From Latin granatum — pomegranate. Look at a handful of small red garnets against the light and the comparison stops being poetic and becomes a description.
Garnet is one of the oldest gems in continuous use anywhere. Egyptian jewellery from five thousand years ago has it, and Anglo-Saxon goldsmiths cut thin garnet slices to fit gold cells with such precision that the technique is still discussed by people who make things for a living. The Sutton Hoo shoulder clasps are the reason a lot of people in Britain have seen garnet without knowing they had.
Wearing it
Garnet runs 6.5 to 7.5 on the Mohs scale depending on which member it is — rhodolite and almandine sit near the top of that range, which is fine for daily wear. It has no cleavage, so it does not have a weak direction, and that matters more than the hardness number for a ring that gets knocked.
Warm soapy water and a soft brush. Avoid steam and ultrasonic cleaning on stones with visible inclusions.
What we make for January
Burning Heart is a heart cut from garnet on a blackened silver band — the least fussy way into the stone we make, and the entry price of the whole catalogue.
For rhodolite specifically — the raspberry-violet blend, and the better-looking half of the garnet family — The Turning Wing is a butterfly ring and From the Root is a double-finger tree ring. Quick Wing uses black garnet in a dragonfly necklace, which is the same family at the opposite end of the light.
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 January stone is deep red. It is cubic zirconia cut to the birthstone colour, not garnet. 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 garnet has been used to mean →
A birthstone is a date, not a diagnosis. Nothing here treats, prevents or cures anything.