54 crystals and stones with their planets, history and lore from Pliny to the Victorians, magical uses, care (water, salt, sunlight) and safety — with a stone of the day, your birthstone, when to charge each one, the hardness scale, and your own collection with its gaps and storage advice. The stones that belong to the Hindu navaratna say which planet they serve. Every stone is set on the Mohs scale of hardness, with a scratch test between any two, and a quartz crystal can be turned in the hand and coloured as each of the quartz family, from rock crystal to flint.
Steadiness, eloquence and protection — a stone for students, speakers and travellers.
More ▾Less ▴
Pliny says it was named after the river Achates in Sicily, where it was first found. Banded “eye” agates were worn against the evil eye throughout the ancient world.
Good for
Protection, Grounding, Focus & study
Cleanse with
incense smoke, moonlight, a rinse in running water, an hour of morning sun
Water: rinse OKSalt: avoidSunlight: fine
Brightly coloured agates are usually dyed.
Fluorite
Easy to handle
Blue John (Derbyshire) · Calcium fluoride · hardness 4 · ☿ Mercury · Air
Focus, study and orderly thought — a modern “student's stone”.
More ▾Less ▴
It gave its name to fluorescence, the glow some minerals show under ultraviolet light. Derbyshire's banded Blue John has been carved into vases and bowls since the 18th century.
Good for
Focus & study, Calm
Cleanse with
incense smoke, moonlight, a rinse in running water
Clear calcite doubles everything seen through it. Experiments suggest it could have been the Vikings' “sunstone” for finding the Sun through cloud — and a piece was found among the navigation gear of a 16th-century English shipwreck off Alderney.
Caution: One of the most faked stones — much “moldavite” is glass. Buy from reputable dealers.
More ▾Less ▴
Natural glass formed when a meteorite struck what is now southern Germany about 15 million years ago, throwing molten rock into Bohemia and Moravia. Its fame as a “stone of transformation” is recent.
Good for
Intuition & divination, Focus & study
Cleanse with
incense smoke, moonlight, a rinse in running water, an hour of morning sun
Water: rinse OKSalt: avoidSunlight: fine
Opal
Handle with care
Hydrated silica · hardness 5.5–6.5 · ☿ Mercury · Air · October birthstone
Imagination, intuition and change — Mercury's many colours.
Caution: Contains water: heat, dry air and long sunlight can crack it. Don't soak opal doublets or triplets.
More ▾Less ▴
Pliny admired it for showing the fire of the carbuncle, the purple of amethyst and the green of emerald at once. Its 19th-century reputation for bad luck came largely from Walter Scott's novel Anne of Geierstein (1829).
Good for
Intuition & divination, Luck, Love & friendship
Cleanse with
incense smoke, moonlight, a rinse in running water
Water: rinse OKSalt: avoidSunlight: fades
How hard is each stone?
In 1812 Friedrich Mohs ranked minerals by which will scratch which, from talc at 1 to diamond at 10. A stone scratches anything softer than itself, which is why soft stones are kept apart from hard ones. Every stone in the library is set on the scale below.
Rest on a dot to see the stone; tap it to look it up.
THE SCRATCH TEST
Amethyst scratches Malachite, and not the other way: keep malachite in its own pouch.
Glass and a steel knife are about 5.5, so any stone softer than that can be marked by a jar, a blade or the dust of quartz. ★ marks the stones in your collection. Test only on a hidden spot, or better, don't: the scale is for keeping stones safe, not for marking them.
One mineral, many stones
Quartz is silicon dioxide, grown as a six-sided crystal with a point. Where the crystals are big enough to see, it gives rock crystal, amethyst, citrine, smoky and rose quartz; where they are too fine to see, chalcedony: agate, carnelian, jasper and flint. Turn the crystal, and choose a stone.
CRYSTALS YOU CAN SEE
TOO FINE TO SEE: CHALCEDONY
Rock crystal: pure silicon dioxide, clear as Pliny's 'eternal ice'.
SETS OF STONES IN OTHER TRADITIONS
The Hindu navaratna
Nine gems, one for each of the nine grahas.
Ruby is for the Sun, pearl the Moon, red coral Mars, emerald Mercury, yellow sapphire Jupiter, diamond Venus, blue sapphire Saturn, hessonite Rāhu and cat's eye Ketu.
They are set with the ruby in the centre. Sources give the outer order differently.
Sanskrit gem-lore is old: Varāhamihira's Bṛhat Saṃhitā, of the 6th century, has a chapter on gems. The planetary set is taught in the later astrological texts.
The stone is chosen from the birth chart, not by month.
WHERE IT DIFFERS The tool follows the planets of the West. Rāhu and Ketu, the Moon's nodes, have gems of their own.
Sources: Skyjems, “Hindu navaratna”
Safety. Stones are symbols and focuses for magic, not medicine. Never put toxic minerals — malachite, turquoise, lapis, pyrite and other metal ores — into water you will drink; keep small stones away from children and pets; and wear a mask if you ever cut or polish stone.
Lore from Pliny's Natural History (77 CE), the medieval lapidaries and G.F. Kunz's Curious Lore of Precious Stones (1913); “modern association” marks 20th-century ideas such as the chakra links. Planets follow the Correspondences tables. Learn more in Stones & Metals.
PRACTISE WITH IT
0 of 4 done
A few things to do with this tool, from a first try to a habit. Each one you tick counts as practice for the day, towards your streak and milestones.
Kept in this browser. Notes you send to the journal are kept there as well.