Gemstones

Gemstone

Hardness

Origin

Wearability

Description

Treatments

Care

Most Value

Alexandrite

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8.5

Russia, Brazil, Sri Lanka

Excellent

Alexandrite is a color change variety of the mineral chrysoberyl. It is extremely rare, and changes from teal green in daylight to red in incandescent light. It is the accepted birthstone for June and also commemorates the 55th wedding anniversary.

No known enhancements; Synthetics and imitations common

Normal care required

Intense teal-green alexandrite with excellent clarity that changes to Reddish-raspberry in Candlelight

Peridot

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7.0

Arizona, Pakistan

Very Good

A form of the mineral olivine, peridot is commonly light to medium green or yellowish-green in color. Peridot is the accepted birthstone for August and is often given on the 16th wedding anniversary.

No known enhancements; Synthetics and imitations common

Normal care required

Peridot from Egypt that is a saturated deeper green with excellent clarity

Emerald

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7.5-8

Columbia, Brazil, Zambia, Zimbabwe

Good

A form of the mineral beryl, emeralds are medium to dark green gemstones. Internal fractures and inclusions are very common and are often referred to as a garden. Emerald is the birthstone for May.

Usually lightly, moderately, or heavily treated; Emeralds are often oiled, filled with resin, and occasionally dyed

Avoid temperature changes, streaming, chemicals, and ultra-sonic

Slightly blueish-green emerald in a medium to dark tone with vivid saturation and excellent clarity

Jadeite

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6.5-7

Myanmar (Burma), China, Japan

Excellent

Different from China's nephrite jade, jadeite jade is very rare and mined only in Myanmar. Japan and China are the main importers of jadeite. Due to human rights violations, all gemstones mined in Myanmar are banned in the US. Although it is also found in lavenders and red, the most desired jadeite is a bright waxy spectral green.

Commonly impregnated with colorless wax, occasionally dyed to imitate natural colors; Imitations very common

Avoid strong light, chemicals, and ultra-sonic

"Imperial Jade" from Myanmar which is bright green, uniform in color, and free from streaks and fractures

Tourmaline

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7-7.5

Brazil, Afghanistan, Australia, Myanmar

Very Good - can be worn in all types of jewelry

Tourmaline is found in all colors, the most common colors being pink and green. Most crystals are multi-colored - the best known being "watermelon."

Green and blue tourmaline commonly heated to enhance color. Pink, Purple, and red are occasionally heated and irradiated to enhance color; Yellow and orange are never enhanced

Avoid temperature changes, steaming, chemicals, and ultra-sonic

"Electric" or "Neon" blue-green Paraibatourmaline from Brazil

Tanzanite

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6.5-7

Tanzania

Good - can be worn in all types of jewelry

A form of the mineral zoisite, tanzanites are intense deep blue in color with underlying hues of purple. Tanzanite crystals are trichroic - meaning different colors are seen when viewed from different axes. Cutting the gemstone along certain axes can enhance more purple or more blue colors depending on the preference of the consumer.

Always heated to remove yellowish color and to enhance the violet-blue color

Avoid sudden temperature changes, extreme high temperatures and the ultra-sonic cleaner; Protect from chipping or scratching if worn in a ring

Deeply cut gemstones that are a very saturated blue in color with slight hints of Lavender when the stone is turned

Sapphire

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9.0

Myanmar, Sri Lanka, Thailand, Madagascar, Montana

Excellent

A form of the mineral corundum, sapphires are found in all colors. Some can change color from blue to violet in artificial light. Sapphire is the accepted birthstone for the month of September. It is often given to commemorate the 5th and 45th wedding anniversaries.

Usually heated to produce, intensify or lighten color and/or improve color uniformity; Heat treatment also used to eliminate silkiness and improve clarity

Normal care required, except if it has been irradiated; Color or irradiated sapphires fades quickly when exposed to light and heat

Unheated sapphires that are saturated electric blue in color with no undertones of blue, black, gray, or green

Lapis Lazuli

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40304.0

Afghanistan, Siberia, Canada, Chile

Good

Commonly used in men's rings, lapis is an opaque bright blue rock composed of lazurite, sodalite, and often pyrite.

Commonly waxed, oiled, heated and dyed; Synthetics and imitations common

Avoid contact with harsh chemicals, high temperatures and ultra-sonic

Lapis that is intense blue in color with violet undertones and has a uniform fine-grained texture; The higher the polish, the harder the stone

Turquoise

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5.0-6

Iran, US, China, Argentina, Australia, Brazil

Poor - best worn in earrings and pendants

Turquoise is an opaque blue, blue-green, to yellowish-green stone usually found in arid regions. Most turquoise has flecks or veins of other minerals such as pyrite.

Treatments very common and include plastic impregnation, dye, wax, and epoxy; The "Zachary Process" is an electrochemical treatment used to increase durability and to even the color; Imitations common

Avoid heat, hot water and household chemicals

Persian turquoise from Iran which is pure blue in color with a few flecks or veins of other minerals

Aquamarine

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7.5-8

Brazil, Zambia, Nigeria, Madagascar, US

Excellent

A form of the mineral beryl, Aquamarines occur in pastel tones from very light to medium blue. Naturally occurs with undertones of green. Large crystals over 5 carats are common. It is the accepted birthstone for March.

Usually heated to minimize green as a secondary color

Avoid steaming or ultra-sonic; Color may fade if exposed to long periods of sunlight

Aquamarine with clear deep shades of blue, cat's eye aquamarine, start aquamarine

Garnet

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7-7.5

Brazil, Madagascar, Namibia, Sri Lanka

Good

The accepted birthstone for January, garnets are found in all shades of red, orange, and green. Color change garnets can change to every hue in the gem world.

Proteus garnets are the only enhanced garnet; They are heat-treated which brings a thin layer of metals to the surface

Normal care required; Protect from chipping and scratching

Extremely rare green demantoid garnets from Russia which have "horsetail" inclusions and whose brilliance is greater than that of a diamond

Ruby

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9.0

Myanmar, Africa, Australia, Madagascar

Excellent

Distinguished from red sapphires by the presence of chromium, rubies are also a form of the mineral corundum. In addition to red, rubies can also display hues of pink, purple, orange, and brown. Ruby is the birthstone for July and is often given for the 15th and 40th wedding anniversaries.

Usually heated to improve color and appearance; Glass is occasionally used to fill fractures

If dyed or if fractures are filled with resin, avoid chemicals and ultra-sonic

Unheated rubies from Myanmar (Burma) that are red in color with slight purplish tones; Rubies larger than 3 carats are extremely rare

Spinel

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7.5-8

Myanmar, Sri Lanka, Cambodia

Excellent

Often found with ruby and sapphire deposits, spinel commonly occurs in red, black, and blue. Spinel has excellent brilliance.

Never enhanced, however many synthetics are made

Normal care required

Cobalt blue spinel which is very rare

Rubelite

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7-7.5

Brazil, Madagascar, Nigeria, US

Very Good

Rubelite is the dark pink to red form of tourmaline that is brilliant in both daylight and artificial light and does not exhibit brown undertones in artificial light.

Commonly irradiated to intensify color from pale pink to red

Avoid temperature changes, streaming, chemicals, and ultra-sonic

Rubelite that is deep pink to red with no hints of brown and with few inclusions

Amethyst

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7.0

Brazil, Uruguay, Zambia

Very Good - can be worn in all types of jewelry

Amethyst is a variety of quartz that is very light to dark purple in color. Larger carat stones are common. It is the accepted birthstone for February.

Almost always heated to bring out its purple color

Color may fade if exposed to long periods of sunlight; Protect from chipping and scratching

"Siberian" amethyst which is rich deep purple and highly transparent

Agate

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7.0

Brazil, Mexico, US, India, Australia

Excellent

Agate is a form of quartz in which individual crystals are too small to be seen with the naked eye. Found in a variety of colors, inclusions can create very intricate designs.

May be dyed; Banded agate is commonly dyed

Protect from chipping and scratching

Natural un-treated agates with rich colors and vivid designs

Amber

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2-2.5

Baltic Sea, Dominican Republic, Mexico, Myanmar

Good

Commonly yellow-orange, amber is formed from fossilized tree resin and can include insect fossils. More rare colors include red, green, blue, violet, and black.

Often heated to deepen color; Oil heated to remove cloudiness; Oil heating can cause highly refractive inclusions called spangles to form

Very heat sensitive; avoid high temperatures

Clear amber with little or no cloudiness

Citrine

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7.0

Brazil, Madagascar, Bolivia, US

Very Good

This variety of quartz is found in all shades of yellow. Large stones over 10 carats are common. Citrine is the alternative birthstone for November.

Almost always heat treated; Sometimes dyed

Protect from chipping and scratching; Avoid prolonged periods of heat or sunlight as color may fade

Natural Madeira citrine which is reddish-orange

Topaz

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8.0

Brazil

Very Good - can be worn in all types of jewelry

Topaz is very brilliant and commonly found in rich yellow, medium peach, blue, pink, brown and colorless stones. Topaz is the birthstone for November.

Blue topaz almost always heated and irradiated to produce the blue color; Orange and pink topaz occasionally irradiated to intensify color

Avoid heat and strong light

Imperial Topaz which is reddish-orange in color and precious topaz which is a rich golden yellow or peach in color

Oregon Sunstone

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6-6.5

Eastern Oregon

Poor - best worn in earrings and pendants

A form of the mineral teraspan, colors include pink, tan, orange, green, red, and multi-color. Sunstones are only found in SE Oregon. Clear sunstones are sometimes called "Plush Diamonds" named after the town of Plush, OR near where they were mined. Schiller sunstones show aventurescence from Copper platelets found within the crystal.

Never enhanced; some limitations include dyed and infused andesine

Avoid temperature changes, steaming, chemicals, and ultra-sonic

Deep cherry red sunstones or those with green and teal hues are very rare

Opal

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5.5-6.5

Australia, US, Mexico

Fair to Poor - best worn in earrings and pendants

Opal, which is formed in ancient riverbeds, is characterized by a play of colors (red, yellow, orange, yellow, blue, and green) called "fire" when viewed from different angles. Opal is the birthstone for October and often given on the 14th wedding anniversary.

Doublets, which have an added dark backing, and triplets, which have a backing and an added layer of quartz over the top, are very common; Opals can be impregnated with oil, wax, or plastic and is sometimes smoked to form black opal; Dyes or chemicals are sometimes used to make white opals black; Imitations common

Avoid heat, chemicals, ultra-sonic, and extreme temperature changes; prone to dehydration and fracture

Black opal from Lightening Ridge, Australia which has intense fire and good durability

Pearl (natural and cultured)

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2.5-4.5

Japan, China, South Sea

Good

Formed by oysters and clams which secrete layers of nacre to coat a foreign object. Naturally occurring colors include white, cream, light to dark gray, light pink, gold, and light green.

Commonly bleached or dyed; Occasionally irradiated for blue and gray coloring; Occasionally heated for brown and purple brown coloring

Avoid cosmetics, perfumes and household chemicals, including alcohol, detergent, and ammonia

Large, saltwater pearls that are perfectly round, have excellent luster, a blemish free surface, and thick nacre

Moonstone

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6-6.5

Sri Lanka, India, Australia

Poor - best worn in earrings and pendants

Very popular in Germany, moonstone is commonly found in yellow, gray, green, pink, and brown. It is characterized by an iridescent billowy floating blue-white light "Centipede" inclusions are common. Moonstone is often cut into high-domed cabochons to enhance sheen.

Glass imitations are common; Dark backing is sometimes added

Easily scratched; Protect from sharp blows

Blue sheen moonstone that is a very translucent blue and extremely rare; Most blue-sheen moonstones can only be found in antique and estate pieces

Diamond

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10.0

Africa, Australia, Canada

Excellent

Diamond is a form of carbon formed under intense heat and pressure deep inside the earth. Usually found in shades of white, fancy colors such as yellow, pink, and blue are extremely rare. Champagne and cognac diamonds with excellent clarity are also popular. Superior cut (ideal proportion and symmetry) is extremely important in creating brilliance and fire. Diamond is the birthstone for April.

Some colors, such as blue, are produced by irradiation; Inclusions are commonly removed by laser drilling and cracks are occasionally filled with glass; New technologies for polishing can hide twinning, which can make diamonds more prone to chipping

Protect from sharp blows

An inclusion that is "D" in color (colorless) and has been cut to perfect proportions and symmetry; Fancy intense yellow and pink diamonds and natural blue diamonds are extremely rare

Black Onyx

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7.0

Brazil

Excellent

A form of gray chalcendony (fine-grained quartz) that is usually heavily treated to obtain the shiny black appearance. It is often carved or cut and polished into cabochons.

Dyeing and heating very common

Protect from chipping and scratching

Natural untreated black onyx which is very rare and found only in Germany

Zircon

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6-7.5

Sri Lanka, Brazil, Australia, East Africa

Good - best worn in earrings and pendants

Zircons, which are different from cubic zirconias, are found in all colors, most commonly red-brown to gray-brown. They have great brilliance and fire that rivals that of a diamond. Green zircons can have radioactive trace elements (uranium, thorium) which decreases brilliance. Blue zircon is the birthstone for December.

Yellow, green, and brown zircon are never enhanced; Heat treatment is always used to produce blue, red, and colorless zircon

Protect from chipping and scratching; Prone to wear around edges; Avoid harsh abrasives

Natural blue or colorless zircons are extremely rare

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