A sign usually takes its stone from the planet that rules it, and Sagittarius is the clearest case on the circle, because its oldest stone is Jupiter’s. A shop today gives turquoise, topaz, lapis lazuli, sodalite and amethyst instead.
Cornelius Agrippa printed his correspondences in 1533, and the first book of his Three Books of Occult Philosophy gives a chapter of stones to each of the seven planets. The chapter on Jupiter opens with hyacinth, and lists beryl, sapphire, tutia, emerald and green jasper after it. Turn to his table of sign stones and the stone he gives Sagittarius is hyacinth. The same stone, at the top of the same writer’s Jupiter list, because Jupiter rules Sagittarius.
That is not a coincidence, and it is not quite a tradition of sign stones either. It is a tradition of planet stones being read off onto the signs each planet governs, and Sagittarius is the cleanest place on the whole circle to watch it happen.
The stone Jupiter actually hands out
Jupiter rules two signs, Sagittarius and Pisces, an assignment Ptolemy sets out in the second-century Tetrabiblos. If Agrippa’s sign stones are really his planet stones in disguise, then both of Jupiter’s signs should draw from the Jupiter chapter, and both of them do. Sagittarius gets hyacinth, which heads the list. Pisces gets sapphire, which is on it. One planet, two signs, two stones, and both stones come off the planet’s own page.
Run the same check on the other planets Agrippa wrote up and it mostly holds. Venus rules Libra and Taurus, and gives them beryl and carnelian, both on the Venus list. Saturn is the exception that keeps it honest: it rules Capricorn and Aquarius and gives them chrysoprase and crystal, and neither is a Saturn stone, because Agrippa handed Capricorn a stone that belongs by his own rules to the Sun. The rule has a hole in it, which is what tells you it is a rule and not an accident.
What it means for reading these old lists is worth being plain about. Agrippa’s row of sign stones is not independent testimony that the signs had stones of their own. It is his planet chapters and his calendar, relabelled and stacked into one table, and once that is clear the sense of an ancient sign-stone lore recedes. Kunz’s 1913 topaz is genuinely on the modern list, which puts it among only nine cells, in the thirty-six-cell grid, where an old stone reappears on the modern list for its own sign; the Aquarius page does that counting and names the two tests. It falls short of the two headline matches only because those ask the old list and the new one to open with the same stone, and here the new one opens with turquoise.
Turquoise, and the calendar it rode in on
The stone at the head of the list has no old claim at all. Turquoise reaches Sagittarius entirely through the birthstone calendar, and the calendar half of this list is younger than most people assume.
Sagittarius runs from about 22 November to 21 December, so it draws on two birthstone months, and Jewelers of America gives November citrine and topaz and December turquoise, tanzanite and blue zircon. Three of those five were assigned within living memory. Citrine and zircon both came in with the 1952 revision, tanzanite was added to December in 2002 by a joint decision of the American Gem Trade Association, the International Colored Gemstone Association and Jewelers of America, and spinel joined August as recently as 2016. The Gems and Gemology note recording the tanzanite decision even called it the first gem added since 1912, which quietly wrote fifty years and a whole revision out of the record. A list people describe as ancient has been edited three times in the memory of people now alive.
Turquoise itself is the softest sort of headline a stone can be. It is a hydrated copper aluminium phosphate at Mohs 5 to 6, and GIA describes it as porous, which is the property the trade works on. Impregnation, filling the pores with wax or polymer to firm the stone up and even the colour, is one of the treatments GIA names turquoise among the stones most commonly given. What follows is a stone that reacts to its wearer. GIA’s care page warns that turquoise can be discoloured by cosmetics, skin oils and perspiration, that heat and solvents damage any treated surface, and that steam and ultrasonic cleaners are out entirely, and its treatments page adds a jeweller’s torch to that, because heat ruins a wax or polymer fill. A sign whose whole reputation is the open road has ended up with a stone that flinches at the touch of a hand.
None of that was planned. It is what happens when a list is put together from a calendar and a temperament rather than from the stone in front of you, and turquoise is the clearest case of it on any sign. The colour looks like sky and distance, the sign is about both, and December supplied the material, so the least durable stone on the page became its headline. A shop selling a Sagittarius set is selling that association, and the association is doing all the work the mineralogy cannot.
Sodalite, amethyst, and the rest
Two of the remaining stones repay a closer look, for opposite reasons.
Sodalite draws the least attention of the five and hides the most in its reference entry. The Handbook of Mineralogy gives it as a sodium aluminium silicate carrying chlorine, cubic, Mohs 5.5 to 6, and records two things a blue tumble does not advertise: it may be photochromic, so the colour can shift with light exposure, and it may give off the smell of hydrogen sulphide when freshly broken. A stone that can fade and can smell faintly of rotten eggs on a new fracture is not what the tray label leads anyone to expect.
Amethyst is the opposite case, a stone with no route to the sign at all. February is its birthstone month, so the calendar hands it to Aquarius and Pisces. Agrippa gave it to Scorpio, the Spanish list of 1604 gave it to Aquarius, and Kunz gave it to Pisces. Every documented list puts amethyst somewhere other than Sagittarius, and it sits here on nothing but a felt match between a purple stone and a philosophical sign, which is a real reason for a pairing and not a historical one. The two kinds of reason get run together on a shop label often enough that pulling them apart is most of what a page like this is for. Lapis lazuli, the fourth stone, is a rock rather than a mineral, and what it is actually made of is taken apart on the Libra page, where it sits for reasons of its own.
Turquoise arrives by the calendar, topaz by the calendar and by Kunz together, and lapis, sodalite and amethyst by resemblance. All five sit in the Crystalance Mineral Library under their mineral names. Only topaz among them reaches back past the birthstone calendar at all, and the older layer it touches is Jupiter’s hyacinth, which is not even the same stone.
Sources
- Cornelius Agrippa, Three Books of Occult Philosophy, Book I ch. XXVI on Jovial stones, 1651 translation of the 1533 original: esotericarchives.com
- Ptolemy, Tetrabiblos I.17, Robbins translation, on the houses of the planets: penelope.uchicago.edu
- George Frederick Kunz, The Curious Lore of Precious Stones, 1913, ch. X: gutenberg.org
- Jewelers of America, birthstones by month: jewelers.org
- GIA and others, Gems & Gemology on the 2002 addition of tanzanite: gia.edu
- GIA, gem treatments, on impregnation and the torch caution: gia.edu
- GIA, turquoise description: gia.edu
- National Jeweler, on the evolution of the birthstone list and the 1952 and 2016 additions: nationaljeweler.com
- GIA, turquoise care and cleaning: gia.edu
- Handbook of Mineralogy, sodalite: handbookofmineralogy.org
