Ruby

The name ruby comes from the Latin ruber, meaning red. For centuries red spinel and ruby were grouped together in the gem trade, and the two can look nearly identical in a ring. Ruby's deep red color led many cultures to link it with blood, fire, power and life force, and it has long been a stone of rank and wealth.

Crystal traditions associate ruby with drive, stamina and courage, and with warmth and passion. Practitioners link it to the Heart chakra and the Root chakra, to the elements Fire and Earth, and to the zodiac signs Leo, Aries and Cancer. Some collectors describe the soft sheen of rutile silk in certain stones as part of the appeal.

People use ruby as jewelry, as polished cabochons, or as raw crystals kept on a desk or carried as a pocket stone. Buyers interested in the metaphysical side should know that many rubies are heat-treated, and some are glass-filled composites. Glass-filled stones can feel lighter, may show blue-orange flash in fractures under a loupe, and do not wear like solid corundum. These associations are cultural beliefs, not proven effects, and they are not a substitute for medical care.

Ruby is the red variety of corundum (aluminum oxide, Al2O3), and most of its color comes from chromium. Good ruby shows both gem and rock character. Many natural pieces are included, fractured, or still attached to matrix, unlike the perfectly clean jewelry stones people often expect.

A decent crystal feels heavy for its size. The faces can be glassy, though not as slick as quartz. Some pieces show the classic corundum form, chunky hexagonal barrel-shaped crystals, sometimes with flat basal faces. Others are heavily worn, with rough edges and chips from long transport and weathering.

Many people expect a pure cherry red, but natural ruby color varies widely: pinkish red, purplish red, brownish red and orangey red. The market is also complicated. Much ruby is heat-treated, and many very red stones are glass-filled composites that photograph well but do not behave like a single solid crystal in handling and wear.

The word ruby comes from the Latin ruber, meaning red. For a long time the gem trade grouped red spinel and ruby together, because the two can look nearly identical in a ring under warm light, and refractometers were not available to buyers or sellers in the 1600s.

Corundum didn’t get formally pinned down as a mineral species until modern mineralogy got rolling, and the name “corundum” is generally credited to work that was popularized in the late 18th century (often linked to European mineralogists like Abraham Gottlob Werner). So once hardness testing, optics, and chemistry finally caught up, “ruby” as “red corundum” became a crisp definition. That’s when a bunch of famous “rubies” sitting in old collections quietly got re-labeled as spinel.

Ruby shows up in metamorphic rocks (marble, gneiss) and in basalt-related deposits where crystals weather out and concentrate in gravels.

Most rubies form when aluminum-rich rocks get heated up and squeezed hard during metamorphism, and a bit of chromium slips into the corundum crystal structure, nudging the color over into red. Marble-hosted ruby is the classic situation. You’ve got the chemistry lined up, lots of heat and pressure, fluids pushing through tiny cracks, and corundum grows in spots where silica is scarce (you’ll often see it right along those white calcite bands).

Basalt-related deposits are a second source. Volcanic activity carries rubies to the surface, and they later accumulate as rounded, waterworn pebbles in secondary deposits, smooth to the touch and slightly frosted when dry. Marble-hosted rubies often show a soft, glowing red with silk, while basalt-related material is usually darker and, in rough form, chunkier and more opaque.

Color: Ruby ranges from pinkish red to deep purplish red, with the red primarily caused by chromium. Many rough pieces show zoning, like bands or patches where the red turns pink, purple, or brown.

Luster: Vitreous luster on clean faces, sometimes leaning slightly silky if there’s rutile “silk” inside.

If you scratch it with a steel knife, nothing happens, and it’ll laugh at glass too since it’s Mohs 9. Look closely at the crystal shape in rough pieces, corundum often shows stubby hexagonal barrels or flat basal faces rather than pointy quartz-style terminations. The real test is a refractive index reading around 1.76 to 1.77, because red garnet and spinel can fool you by color alone.

Ruby is sometimes confused with these materials:

• Red spinel (natural or lab-grown, often sold as “ruby” in older jewelry)
• Red garnet (pyrope/almandine, especially dark “wine red” stones)
• Red glass or leaded glass imitations (sometimes with bubbles and a too-warm feel)
• Flame-fusion synthetic ruby (Verneuil) and other lab-grown ruby sold without clear disclosure
• Composite “ruby” (glass-filled ruby or ruby-in-glass, sometimes called lead-glass-filled ruby)
• Dyed corundum or dyed crackle quartz marketed as “ruby” beads/cabochons (watch for dye in fractures)

Ruby is generally safe to handle and does not react with water under normal conditions. The main hazards are physical. Rough crystals can have sharp edges that catch the skin along a jagged face, and a hard knock can chip the stone and send small fragments flying.

If you’re cutting or grinding corundum, handle the dust like any other fine mineral dust. Use good ventilation (you want that gritty powder moving away from your face, not hanging in the air), and wear a respirator.

Rough/Tumbled: $10 - $5,000+ per piece

Cut/Polished: $50 - $100,000+ per carat

Price mostly comes down to color (a real, true red versus that brownish or purplish look), clarity, whether it’s been treated, and whatever origin it’s being sold as. But the moment you’re looking at a clean, unheated stone that’s got a strong red and some real size to it, that’s when pricing just goes completely off the rails.

Very Durable — Scratch resistance: Excellent, Toughness: Good

Ruby is very stable for daily wear, but it can chip if it takes a sharp hit, especially along fracture planes or in heavily included material.

Use & Storage

Store ruby so it cannot rub against softer stones, since it will scratch them. A small box with individual wraps or gem jars works well, especially for faceted pieces.

Cleaning

1) Rinse with lukewarm water and a drop of mild soap. 2) Gently scrub with a soft toothbrush around crevices or matrix. 3) Rinse well and pat dry; avoid leaving it wet in a closed container.

Cleanse & Charge

For those who follow the metaphysical tradition, a simple rinse and a few minutes in sunlight are commonly used. Avoid leaving ruby on a hot windowsill for hours. Heat is used in treatment, and brief sun will not harm ruby, but display stones more often look dull from grime and constant handling than from any other cause.

Placement

On a desk, ruby reads best under a focused light where you can catch internal silk or zoning. In a pocket, go with a cab or a well-polished piece, because rough crystals can chew up your keys.

Caution

Don’t use an ultrasonic cleaner on rubies that are badly fractured or glass-filled. Those vibrations can open up the cracks you can already see under a bright light (that little spiderweb look) and they can even chip away at the fillings. And before you assume you’ve got one solid crystal, ask what treatments it’s had. Why guess?