O
OBSIDIAN
Name: from the Latin “obsidianus” (a misspelling of “obsianus”). Pliny the Elder claimed it was named after Obsius, a Roman explorer who “discovered” it in Ethiopia.
AKA: The Stone of Truth.
Description: It is technically an extrusive igneous rock rather than a mineral. It has a smooth, glassy texture and razor-sharp conchoidal fractures. It is formed from the rapid cooling of silica-rich lava and is considered volcanic glass.
Chemical Composition: SiO2 with impurities.
Color: Primarily jet black but comes in a variety of colors (black, gray, brown) and sheens (gold, silver, blue). Some varieties include: Snowflake (white cristobalite inclusions in black); Mahogany (brown to red iron streaks with black); Rainbow (blue, green, pink, yellow, silver, gold).
Treatments: Rarely treated.
Moh’s Hardness: 5.0 – 5.5
Toughness: Brittle.
Location Found: Iceland; Italy (Lipari Islands); Japan; Mexico; New Zealand; USA (Arizona, California, Oregon).
Birthstone: December; November.
Wedding Anniversaries: 10th.
Zodiac Signs: Capricorn; Sagittarius; Scorpio.
Chakra Associations: Root; Earth Star.
Historical Associations: scrying; seeing the future; divination; cutting cords; truth; breaking toxic emotional attachments; absorb negative energy from the aura; absorb negative energy from the environment; confront fears; confront flaws; confront repressed emotions; bring a scattered mind back to the present moment; surgery; mirrors; arrowheads; spear points; knives.
Historically Used to Treat: poisons; viruses; emotional sludge; digestive cramps; back pain; joint pain; circulation.
Care: Avoid harsh acids which can dull the glassy luster over time. Use warm, soapy water and a soft cloth to clean. Dry with a soft cloth. Store in a separate soft pouch so it doesn’t get scuffed by your jewelry.
Imitations: Black Glass. Black Slag. The man-made glass lacks the slight internal imperfections or “flow lines”.
ONYX
Name: from the Greek “onyx” meaning “fingernail” or “claw”.
AKA: Venus’s Fingernails. Stone of Self-Mastery.
Description: chalcedony characterized by straight, parallel bands that are usually black and white.
Chemical Composition: SiO2
Variety: of banded chalcedony
Color: black and white.
Treatments: Dyeing is nearly universal. Solid black onyx is almost always gray chalcedony soaked in a sugar solution and then carbonized in sulfuric acid to achieve a deep, uniform black.
Moh’s Hardness: 6.5 to 7.
Toughness: Good to Excellent.
Location Found: Brazil; India; Madagascar; United States; Uruguay.
Birthstone: December; July.
Wedding Anniversaries: 7th, 10th.
Zodiac Signs: Capricorn; Leo.
Chakra Associations: Root.
Historical Associations: mourning; absorb grief; a psychic sponge; physical stamina; mental stamina; banishes flighty or impulsive thoughts; confidence; a sense of quiet authority; self-mastery; decision making; inner strength.
Historically Used to Treat: bone marrow diseases; fractures; tinnitus; ear infections; childbirth pain; gluttony; impulsive behaviors.
Care: Heat may change color. Usually stable to light, but stones dyed with organic dyes can fade. Avoid harsh chemicals. Attacked by hydrofluoric acid. Ultrasonic and steam cleaning are usually safe. Use lukewarm water and a soft cloth. Dry immediately to avoid water spots. Do not let it sit in dirty water or near oils/perfumes, as it can absorb them and lose its polish as it is porous. Store separately from diamonds, sapphires, and rubies as they can scratch it.
Imitations: Black Glass; Plastic; Black Spinel.
Synthetics: No commercial synthetics exist.
OPAL
Name: Opal comes from the Sanskrit word “upala” meaning “jewel”. The later Greek word for opal, “opallios” means “to see a change in color”.
AKA: Eye Stone. Stone of Intensification.
Description: Opal is a form of silica and is a mineraloid with two broad classes, precious and common. Precious opal gets it play-of-color (iridescence) from its internal structure and results in flashes of colors that can be blue, green, purple yellow, red, orange and the background color may be white, gray, black, or nearly any color of the spectrum. Common opal does not have iridescence. Opals can be transparent, translucent, or opaque. Black opal is considered the rarest of the colors of opal, whereas the white, gray, and green opals are most common. Today, the most sought after color of opal is the black opal.
White Opal: translucent to semi-translucent with play-of-color against a white or light gray body color.
Black Opal: translucent to opaque with play of color against a black or other dark body color.
Fire Opal: transparent to translucent with brown, yellow, orange, or red body color. Often doesn’t show play of color. Also known as Mexican opal, gold opal, or sun opal.
Boulder Opal: is opal attached to a host rock.
Hydrophane Opals (Ethiopian) are especially porous and will absorb liquids and need to be stored with a small damp cotton ball in a pouch, or in water, to prevent dehydration.
Doublets & Triplets: Opal doublets and triplets enhance the appearance and perceived value of a thin or lighter piece of opal by amplifying its play-of-color. Both the doublet and triplet are made by bonding a thin layer of precious opal to a dark backing material, which is usually black potch or ironstone. The triplet has an additional protective layer of clear quartz or glass bonded on top of the precious opal layer.
Doublets: consists of a layer of opal over a backing.
Triplets: consists of a layer of opal over a backing with a protective top made of rock crystal quartz or colorless glass.
Play-of-Color Patterns:
Pinfire or Pinpoint: small, close-set patches of color.
Harlequin or Mosaic: broad, angular, close-set patches of color.
Flame: sweeping reddish bands or streaks that shoot across the stone.
Peacock: mainly blue and green.
Chemical Composition: SiO2⋅nH2O (hydrated silica)
Color: includes white/light, black (dark body tone), fire (yellow, orange, red).
Treatments:
Impregnation w/ oil, wax, or plastic improves play-of-color and prevents or disguises fracturing. Black plastic also creates the appearance of black opal. Stability is fair to poor for oil or wax; excellent for plastic. Common treatment. Detectable by a trained gemologist.
Soaking in dye, silver nitrate, or sugar and acid (known as “sugar treatment”) creates or improves play-of-color and simulates the appearance of black opal. Stability is poor to good. Common treatment. Detectable by a trained gemologist.
Smoke impregnation creates or improves play-of-color and simulates the appearance of black opal. Stability is fair to poor. Treatment is shallow, and abrades or chips away easily. Common treatment. Detectable by a trained gemologist.
Moh’s Hardness: 5 to 6.5.
Toughness: very poor to fair.
Location Found: Australia (black and white opal, boulder); Brazil (white opal); Ethiopia (welo opals); Honduras; Mexico (fire opal); Peru; USA (Arizona, Arkansas, California, Idaho, Louisiana, Nevada, Oregon, Utah, Washington).
Birthstone: October.
Wedding Anniversaries: 14th, 34th.
Zodiac Signs: Libra; Pisces; Scorpio.
Chakra Associations: all, varies by color. Crown (white), Root (black), Sacral (fire).
Historical Associations: the Heavens; lightning; good luck; prophecy; hope; purity; truth; power to preserve the life and color of blond hair; magic; beauty; love; passion; desire; invisibility; inspiration; artistry; spontaneity; amplify emotions; helps one to face their true self; living in the moment; joyful tears; the Creator; Quetzalcoatl; good fortune; innocence; joy; happiness; banish evil; carefree; emotionally expressive; reveal the true nature and character of the individual wearing it.
Fire Opal: fostered creativity and beginnings; bring about necessary destruction.
Historically Used to Treat: disease; eye health; sight; fevers; infections; insulin regulation; labor; mood swings; digestive issues; skin issues; emotional trauma; headaches; insomnia.
Misinformation: The first accounts of opals being “bad luck” came from the 1800s through two works of fiction, Sir Walter Scott’s 1829 fiction novel, “Anne of Geierstein,” where they were first introduced as “bad luck charms,” and again in Charles Dickens’ 1874 fiction novel, “The Opal Ring” where he reiterated that opals were “bad luck charms”. From these two fictional sources the rumor took on a life of its own and became a fact. The common misconception that opals are “bad luck” is still prominent in the collective mindset.
Care: High heat or sudden temperature change can cause fracturing. Generally light stable, but heat from intense light can cause fracturing (known as “crazing”). Loss of moisture and crazing can result from storage in airtight containers. Attacked by hydrofluoric acid and caustic alkalis. Hydrophane opals are especially porous and will absorb liquids which can ruin their play of color. Never use an ultrasonic or steam cleaner. Warm water, mild soap and a soft cloth are safe to use for cleaning. Storage of hydrophane opals should be with a damp cotton ball in a pouch that can help prevent dehydration. Store in a soft pouch, or box, away from other jewelry that can scratch or damage the stone.
Imitations: Glass; Plastic; Slocum Stone (glass).
Synthetics: available in a variety of colors. Gilson (laboratory grown silica spheres). Kyocera/Inamori (often contains a plastic binder). Synthetics usually show a “chicken wire” or “lizard skin” pattern under magnification.