• Cryptocrystalline aggregate of quartz • Translucent to opaque • Banded, multicolored
• Lots of named types
– Ex. Botswana Agate
– Ex. Mexican Lace Agate

• Good jewelry stone

• AMBER
– Organic, fossilized resin from Baltic or Dominican Republic
– Soft, sensitive to chemicals

– Many enhancements and Imitations

• AMETRINE
– Bi-colored variety of quartz from Bolivia
– Can be cut to separate or blend colors

– Synthetics are made

• Purple, single crystal quartz• Many shades such as:
– Siberian
– Rose d’ France
• Good jewelry stone • Brazil, Uruguay & Zambia major sources
• Fashioned in many ways • Birthstone for February


• AMMOLITE:
– Fossilized ammonite shell, Canada is major source
– Iridescent

– Stabilized for durability

• ANDALUSITE
– Pleochroic
– Lesser known jewelry stone
– H = 7.5
– Brazil is major source



• APATITE
– Delicate gem: H =5, cleavable, heat sensitive
– Phosphate mineral (similar to that in your teeth)
– Yellow, green and blue green
– Cat’s eyes occur



• BLUE GREEN TO BLUE BERYL
– H = 7.5 Good jewelry stone
– Colors from pale to medium dark
– Transparent to opaque
– Fashioned many ways
– Brazil is major source, Africa, for darker stones
– Generally heated
– March Birthstone


– Fragile collector stone,(not rare)
– H = 3
– Cleavable



• Cryptocrystalline aggregate of quartz
• Single color,translucent
– Several named forms: Holly and other blue chalcedonies, chrysoprase, gem silica, carnelian
• Excellent jewelry stone



• Durable and brilliant jewelry stone, H = 8.5 • Most common in yellow shades • Cat’s eyes highly valued  • Color change variety is Alexandrite • Sri Lanka is today’s main source, some from Africa • Rare bright green form colored by Vanadium



• Yellow to orange variety of single crystal quartz • Usually heated amethyst • Good jewelry stone  H = 7 • Major source is Brazil • Alternate November Birthstone


• Two types both organic
-Calcareous or stony coral
• Calcium carbonate • White, pink, red • Often dyed or simulated
–Proteinaceous coral

• Made of hair-like protein • Heat sensitive • Black, gold, blue • Sometimes bleached

• Most valuable form of garnet, especially if Russian origin • Green to yellow green color • High dispersion and luster • Horsetail inclusions diagnostic of Russian source, increase value



– Chrome green type is popular as simulant of Tsavorite, but more delicate
– Cat’seye variety occurs



• Chromium or Vanadium containing beryl of medium or darker color (lighter = green beryl)
• Virtually always oiled • Gentle-care gem • Major sources are Colombia, Zambia and Brazil
• May Birthstone


• Amazonite
– Microcline
– Colored by lead

– H = 6

• Labradorite
– Plagioclase
– Directional shiller

– Spectrolite has vivid colors

• Moonstone
– Orthoclase
– Shows adularescence
– Near transparent to opaque

– Blue and “true” rainbow most valuable

• Sunstone
– Oligoclase
– Shows aventurescense
– Transparent material from Oregon, with and without “shiller”

– Translucent and opaque from Tanzania and India

• Fluorite
– Soft and cleavable
– Many colors
– Widely distributed
• Fossil Organisms
– Animals, plants, microbes
– Many processes of fossilization
• Petrifaction
• Impressions
• Casts



• Traditional garnet varieties • Medium dark to dark red with brownish tones • Can be very dark • Historically important • Good jewelry stone • Birthstone for January (all forms)



• Golden Beryl (Heliodor)
– Often irradiated white beryl (Goshenite)

– Good jewelry stone

• Grossular Garnet
– Colorless, yellow, orange and light green
• Colorless is rare
“leucogarnet” collector stone

• Orangey Hessonite has “treacle” inclusions that are diagnostic

• Gaspeite
– Iron and Nickel carbonate mineral
– Unique color popular in
“Southwestern” jewelry

– Sources: Canada, Australia

• Natural Glass
– Several types
• Moldavite & other tektites
• Libyan Desert Glass
• Obsidian
– Bubbles and swirl inclusions


• Hauynite
– Ultra-rare collectors stone

– Constituent mineral of lapis lazuli

• Hemimorphite
– Zinc containing mineral
– Fluoresces bright orange

– Similar in appearance and sometimes confused with Smithsonite

• Extremely pleochroic  gem • Good jewelry stone H = 7 • Frequently too light or too dark

• Major sources: Sri Lanka, India, Madagascar

• Jadeite
– More valuable type
– More saturated colors, greater translucency possible
• Nephrite
– Wider range of colors
– Less expensive
• Both are sometimes bleached, dyed and/or stabilized (more likely with
jadeite)

• Both are exceptionally tough aggregates

 

• Cryptocrystalline quartz aggregate
• Opaque solid color or patterned
• Many named types
– Imperial, Biggs, Bloodstone, Mookaite, Plum Blossom

• Excellent jewelry stone

 

.Pink spodumene
.Cleavable so gentle wear needed

.Moderate fading due to light

• Kyanite
– Rare material in gem quality
– Noted for directional hardness H = 5 & 7
• Larimar
– Gem blue variety of mineral pectolite
– Found only in Dominican Republic




• A rock, not a single mineral
• Ancient gem
• Often contains white bcalcite and/or golden pyrite inclusions
• Highest grade from Afghanistan
• “Denim” lapis from Chile

• Simulants exist

 

• Malachite
– Soft copper mineral
– Idiochromatic green due to copper content
– Characteristic banded
appearance
• Mawsitsit
– Burmese jade containing rock
– Single location
– Excellent jewelry stone

• Morganite
– Light pink beryl
– Usually heated
– Excellent jewelry stone
• Myrickite
– Name for rare type of chalcedony inter-grown with mercury sulfide mineral, cinnabar
– White to brown or grey with red/orange

– One major locale, in California

 

• Amorphous hydrated silica gel
• Many varieties
– Precious with color play
– Common without
• Many locales
– Australia, Mexico, Brazil, Peru, Nigeria, USA
• Fragile gem, H = 6
– Fragility related to water content
– Assembled stones and stabilization possible, synthetics & imitations, too
• October Birthstone



• Pearls today are cultured, natural rare
• Saltwater and Freshwater types
• Bead and tissue nucleation processes
• Different body colors and surface iridescence (orient)
• Many enhancements, bleaching, dyeing, irradiation
• Simulants “faux” still popular
• June Birthstone



• Gem grade olivine
• Idiochromatic, colored by iron
• Relatively good jewelry stone H = 6.5 not fragile
• Major locales
– Arizona, Pakistan, China, Norway, historically Egypt
• Birthstone for August


– Brecciated tiger’seye quartz
– Brown, blue-grey, chatoyance with brown, red or black matrix
– Major source: Namibia
– Minor source: China


• Numerous varieties: rose, smoky, milky, girasol, star, cat’seye, dendritic, rutilated, etc.
• All make good jewelry stones
• Some highly collectable
• Few enhancements
– Rose and smokey can be irradiated


• Red, chromium containing variety of medium to dark red, corundum
– No agreed upon line between ruby and pink sapphire
• The most valuable jewelry stone
– Best stones (Burmese) are very slightly purplish to pure spectral vivid red, with visible fluorescence
• Enhancements, synthetics and simulants on market
• Good-excellent jewelry stone
• Birthstone for July



• Titanium and Iron containing corundum
• Various sources and shades of blue: Ceylon, Australian, Burmese, Kashmir
• Numerous enhancements, synthetics and simulants
• Superb jewelry stone
• Most popular colored stone

• Birthstone for September

 

SAPPHIRE-FANCY
• Any color corundum except blue or red
– Pure Al203 is white sapphire
– Various chromophores for colors: golden, pink, purple, green, padparashah
• Many sources
• Superb jewelry stone

• May be enhanced, synthetic or simulated

 

• Scapolite
– Colorless, yellow and light purple are natural
– Dark purple from irradiation
– Cat’seyes occur
• Serpentine
– Magnesium containing aggregate silicate
– H = 5
– Historical jade simulant



• Historically important ruby and sapphire simulant
• Beautiful, underappreciated gem in its own right
• Durable and bright gem, excellent for jewelry
• Comes in most colors except white and green
• Synthetics widely used as imitation birthstones



• Sphene (Titanite)
– Soft and somewhat fragile
– High RI and very high dispersion
– Pleochroic with high BR
• “Sugilite”
– Purple rock with varying amounts of sugilite mineral and chalcedony
– Most valuable material is translucent
– Single location, S. Africa



• Taaffeite (tar-fite)
– One of the rarest gems on Earth
– Mistaken for spinel, until Gemologist Count Taaffe found it to be DR
– H = 8
• Tanzanite
– Heated zoisite, highly pleochroic
– One locale, supply diminishing
– Too soft and fragile for daily use rings, but gentle use OK
– Newly adopted Birthstone for December



• Hard but fragile gem, careful use in jewelry
• Pure mineral is white
• Blue topaz is result of irradiation, then heating, of white
– Alternate Birthstone for December
• Precious topaz ranges from light yellow through peach and apricot shades to the deep orangey red of “Imperial”
– Traditional Birthstone for November



• Complex borosilicate mineral group: major sources = Brazil/Africa
– Many species and varieties: achroite, indicolite, rubellite, dravite, watermelon, Liddacoatite,
elbite, schorl
• Good jewelry characteristics, H = 7.5 not extemely fragile
• Comes in every color from white through black in various grades
• Name from “turmali” = rainbow



• Tsavorite
– Variety name for medium dark to dark green transparent grossular garnet
– Found only in two locales in Africa
– Relatively good jewelry stone, but not for daily wear rings

• Turquoise: December Birthstone
– Blue to green copper phosphate mineral
– Sensitive to chemicals, sometimes stabilized or waxed. Simulants exist.
– With or without black to brown matrix
– Many sources, but highest quality historically from Persia, today from Arizona



• Historically important, good jewelry stone
• H = 7.5, High RI
• Heated stones: blues, yellows, reds and whites mostly, can be brittle
• Blue is December Birthstone

• Reputation unfairly tarnished by erroneous association with synthetic CZ