Garnet in Depth
A family, not a stone
Garnet is a group of related silicate minerals that share a crystal structure but differ in chemistry, and they are not all red. Almandine is the common deep iron red. Pyrope is the brighter blood red of Bohemian jewelry. Spessartine is orange, grossular gives you both cinnamon hessonite and green tsavorite, andradite produces the intensely green demantoid, and uvarovite forms tiny emerald green crusts.
They crystallize in the cubic system and characteristically form rhombic dodecahedra, twelve-sided crystals with diamond-shaped faces, or trapezohedra. Finding a garnet in schist that grew its own complete crystal faces inside solid rock is one of the more satisfying things in field mineralogy. Hardness runs 6.5 to 7.5 depending on species.
Reading what you have
Since garnet varieties differ, it helps to know which one is in your hand. Almandine from India and Brazil is what most tumbled red garnet is, often quite dark and nearly opaque in larger pieces. Rhodolite, a pyrope-almandine blend, is the purplish raspberry color and the most attractive of the common reds.
Garnet is also used industrially as an abrasive, which tells you something practical: it is hard and it has no cleavage, only an uneven to conchoidal fracture. That makes it more durable in a ring than moonstone or fluorite by a wide margin, though sharp corners on faceted stones can still chip.
One more practical note: garnet is common enough in metamorphic rock that you can find your own. Mica schist in New England, Scotland, and the Alps regularly holds dark red almandine crystals weathering out of the surface, and a single well-formed dodecahedron picked up yourself tends to mean more than a bought tumble.
Practice
Garnet's traditional themes are commitment, vitality, and returning after absence, and the Persephone story with the pomegranate seeds sits behind a lot of that. The name itself comes from the Latin for seed-like, from the resemblance to pomegranate arils.
People use it at the start of things that need staying power rather than a burst: a long project, a reconciliation, a training program. Carrying a small stone or wearing it against the skin is more common than grid work. It gets placed at the root or the base of the spine in layouts, and some practitioners keep it out of night-time arrangements because it is described as activating.
Care and companions
Garnet is water safe and sunlight safe, and warm soapy water with a soft brush suits it well. Avoid ultrasonic cleaning on stones with visible inclusions or on demantoid, which has the horsetail inclusions that make it valuable and fragile. Thermal shock is the main real risk. Some garnets are sensitive to sudden temperature swings.
It is the January birthstone and pairs with Capricorn, Aquarius, and Scorpio. It works with carnelian for a sacral and root combination, with clear quartz for amplification, and with black tourmaline when you want the drive contained. Ruby and garnet together are redundant rather than complementary, so pick one.