Jade – Confused? Here’s Why:

I’m often asked if I make jade jewelry. The answer is yes… and no. That’s because there are two different gemstones that can correctly be called jade. They are similar in hardness and can sometimes be difficult to tell apart visually, but they are very different chemically. Both have been used for thousands of years for tools, decorative carvings and jewelry.

Things that ARE jade:

Nephrite Jade: chemical formula Ca2(Mg,Fe)5(OH)2. Nephrite is found in many countries including along the west coast of North America (sometimes called Canadian or B.C. jade) and also in Australia and New Zealand where it is often used for carved pendants. I’ve most commonly seen it in bright medium and dark greens to almost black but it can also be grayish or brown as well. Nephrite is generally more affordable than jadeite. Here’s an example of one of my recent pieces incorporating nephrite:

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Fossil orthoceras with nephrite jade (item FOSSN104)

Jadeite Jade:  chemical formula NaAlSi2O6. Jadeite is also found in the US and Canada, parts of Europe, and Myanmar. This is the jade that comes in colors including apple-green, white, and pale purple. It often has a mottled appearance. It is available as beads but tends to be very expensive.

Jadeite is commonly treated and has been categorized into 3 types based on this:
Type A – Natural, untreated, may have a surface coating of wax; “true” color.
Type B – Chemically bleached to remove impurities then impregnated with wax or polymers.
Type C – Dyed to enhance color; often chemically bleached and/or impregnated with wax or polymers.

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Aventurine and cultured pearl necklace (item PEGFN102)

Gems that can be confused with jade:
Aventurine: A quartz that gets its green color from inclusions of green chlorite mica. Aventurine is harder and significantly less expensive than either type of jade and has beautiful color. I often use it in my jewelry.

Unfortunately, some gemstones are given  trade names that are descriptive rather than accurate. Some trade names are intended to make a stone sound more expensive or desirable. Here are a few examples with their actual identity:
African Jade: grossular garnet
Australian Jade: chrysoprase
Malaysia Jade: dyed translucent quartz
Mountain Jade: dyed high-grade dolomite marble
New Jade: serpentine
Olive Jade: serpentine

Buyer beware – don’t pay jadeite prices for nephrite, aventurine, or any of the other stones I’ve listed above. Proper gemological testing can easily identify these gemstones.

For more information:
http://www.gia.edu/jade

Nephrite:
http://www.mindat.org/min-2881.html
http://www.gemdat.org/gem-2881.html

Jadeite:
http://www.gemdat.org/gem-2062.html
http://www.mindat.org/min-2062.html

Amethyst: Power to the Purple!

amethyst

Amethyst crystals, cut gem, and beads

February’s birthstone is amethyst, the purple variety of quartz.

Last month I told you about the many different colors of garnets, which are caused by differences in chemical formula. Pure quartz (chemical formula SiO2) is colorless (and is called “rock crystal” in the jewelry industry). The different colors of quartz* are caused by defects in the crystal structure rather than by a consistent change in the  chemical formula. This often causes different amounts of color within even a single crystal (“color zoning”). For amethyst, iron, and possibly aluminum, impurities are believed to cause the purple color.

Amethyst deposits are found all over the world; many of the large mineral specimens come from Brazil and Uruguay, but other sources for the gem include Russia, Czechoslovakia, Zambia, and the United States. It is not uncommon to find relatively large crystals which makes this a very affordable gem, even in large sizes.

Other facts – Amethyst:

  • is the gemstone for those celebrating their 6th or 17th wedding anniversary
  • was believed to prevent intoxication—amethystos means “not drunk” in ancient Greek
  • is sometimes found in combination with citrine and is then known as “ametrine”
  • when heated can change color to become a golden citrine
  • has a hardness of 7 on the Moh’s scale

*Other quartz gemstones include citrine (yellow), aventurine (green), rose quartz (pink), tigers eye (brown), smokey quartz (brown or gray) and chalcedony (which includes jaspers and agates).

Sources:

  • Gemological Institute of America, Gem Encyclopedia page on amethyst: click here.
  • Manual of Mineralogy, 20th Edition, Cornelis Klein and Cornelius S. Hurlbut, Jr., 1977.
  • GemSelect

Garnets are Red … Sometimes

January’s birthstone, garnet, is generally associated with the color red. But did you know garnets also come in orange, green, brown, and other colors?

Garnets are actually a group of gems with similar, but slightly differing chemical formulas.  The generic formula is A2B3(SiO4) where A is calcium, magnesium, iron or manganese (Ca, Mg, Fe, Mn) and B is aluminum, iron or chromium (Al, Fe,Cr). The different combinations of elements create the different species of garnet (listed below with their common colors). Color can be a very helpful diagnostic feature when identifying some (but not all) gems.  For instance, spessartine garnet must always have an orange color component.

min_garnet

Almandine garnet collected at Gore Mountain in New York (left), spessartine garnet crystal (locality unknown, right)

  • Pyrope: medium to dark reddish orange, red through slightly purplish red to pale pink, colorless
  • Almandine: brownish orange to brownish red to purplish red
  • Spessartine: orange, brownish orange, yellowish orange, reddish orange, and red-orange
  • Grossular: medium to dark orange, medium to dark green to yellowish green, colorless
  • Andradite: yellow to slightly greenish yellow or brown, green through yellow-green
  • Uvarovite: light to dark green through yellow-green to brownish green
  • Hydrogrossular: pink, green, brownish pink, white, gray

Because of the range of chemical formulas possible, garnets may also be mixes of more than one species.  In addition, some species have subspecies (called varieties).  Some examples are Demantoid (a variety of Andradite) and Hessonite (a variety of Grossular)

Some garnets also display “phenomena” such as stars, cat’s eye, and color-change due to features of that stone that affect how light is reflected and/or transmitted.

Other facts – Garnet: 

  • is the gemstone for those celebrating their 2nd wedding anniversary
  • is used as an abrasive
  • has been used in jewelry since ancient times
  • can be found in all three major rock types: igneous, sedimentary and metamorphic
  • has a hardness of 6.5-7.5 on the Moh’s scale

and comes in colors to please almost everyone!

GASSN102_a

Sources:

  • Gemological Institute of America, Gem Encyclopedia page on garnets: click here.
  • Gemological Institute of America, Gem Identification Lab Manual, 5/2012
  • Manual of Mineralogy, 20th Edition, Cornelis Klein and Cornelius S. Hurlbut, Jr., 1977.

Gift Giving: Gems with Significance

Most people are aware of birthstones, the gems associated with the month a person was born in, but did you know that specific gemstones are also associated with anniversaries, zodiac signs, historic customs, religions, and metaphysical healing?  Here’s a partial guide to help you with some classic or perhaps some unusual options to give a jewelry gift with extra meaning.

TUSSN101

Turquoise

Birthstones (traditional and modern):
January: garnet
February: amethyst
March: aquamarine or bloodstone
April: diamond or rock crystal (quartz)
May: emerald or chrysoprase
June: alexandrite, moonstone or pearl
July: ruby or carnelian
August: peridot or sardonyx
September: sapphire or lapis lazuli
October: opal or tourmaline
November: topaz or citrine
December turquoise, zircon or tanzanite

Anniversary Gemstones: (it’s a long list so here’s a link)                                         http://gemologyonline.com/anniversary.html

Chakra Gems: Different sources tend to provide slight variations on gems for metaphysical purposes.  Here’s are some links (this is not an area in which I have expertise so you may find better options):

http://healing.about.com/od/astrology/a/zodiacstones.htm                                                               http://gemologyonline.com/chakra.html                           http://balance.chakrahealingsounds.com/chakra-colors-stones/

 

Hematite, Imitation Hematite and Disclosure

Hematite

Hematite is a naturally occurring mineral with the chemical formula Fe2O3. It is mined as an ore of iron and you’ll notice it’s quite heavy because of that iron content. It is commonly metallic steel gray to reddish brown.

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Imitation hematite necklace on natural hematite specimen

Imitation Hematite

You may notice that hematite jewelry is relatively inexpensive compared to other gemstone jewelry. There’s a very good reason for that – almost all hematite beads are imitation. This means that they look like the natural mineral, but they are man-made.  This is also why you’ll see imitation hematite in so many more shapes than natural gemstones (including the rings in the necklace shown above). The larger bead companies that sell on-line are generally very good about providing information on synthetics, imitations and treatments and may use names like “hematine” and “hemalyke” to denote imitation hematite. Magnetic hematite is also an imitation gem. Imitation gemstones are not “bad” – they have a place in the gem world in providing beautiful and generally more affordable versions of rare gemstones. I love the look of hematite and often create and wear imitation hematite jewelry.

Disclosure

In the jewelry industry, ethical dealers tell customers when a gem is imitation, synthetic or has been treated in some way.  This is called disclosure. However, when at bead shows, I’ve learned that some sellers are not as knowledgeable about their products as they should be and do not provide this information.  So, when I buy beads, I ask lots of questions and consider the items carefully before purchasing.  This does not mean that I have not been fooled!  When buying at gem shows, it’s just not possible to have all the necessary equipment to do testing. I generally assume that any “hematite” beads that I buy are imitation and you probably should too!

Thanks for reading!

Gem vs. Mineral

What’s the difference between a gem and a mineral?

Some, but not all, minerals are gems, and some, but not all, gems are minerals.  Confused?  Good, then we’re ready to start.

amethyst

Amethyst is both a mineral and a gem

A GEM has the following properties:

  • Rarity
  • Beauty
  • Durability

A MINERAL has these properties:

  • Inorganic
  • Naturally occurring
  • Set chemical formula or range of formula
  • Solid with unique crystalline atomic structure

(A rock is composed of more than one mineral although a large mass of a single mineral can also be called a rock.)

In general, the properties for gems are much more loosely defined than those for minerals.  Let’s look at some of these properties.

Rarity: Rarity describes how common a gem is and can change as gem deposits are mined out or new sources found. Rarity is also relative to each individual gem; for instance, large inclusion-free amethysts are common, but large inclusion-free emeralds are extremely rare. Generally, the “cleaner” and larger the gem, the rarer and therefore more expensive it will be.

Beauty: Not everyone agrees on what is beautiful, but there are gems for just about everyone’s taste.

Durability: Durability is a gemstone’s ability to withstand wear, heat, and chemicals. Durability consists of three properties: hardness, toughness, and stability. Hardness means how well a gemstone resists scratches and abrasion. Toughness describes how well a gemstone resists breaking and chipping. Stability means how well a gem resists chemicals and temperature changes. (http://www.gia.edu/diamond-care-cleaning)

Inorganic: Not a previously living plant or animal.

Naturally occurring: Not made by humans.

Set chemical formula or range of formula and unique crystalline atomic structure: This is what creates specific crystal shapes and consistent properties for a given mineral.

Examples of gems that are not minerals:

  • Pearls, fossils and amber (“organic” gems)
  • Any synthetic gem (not naturally occurring)

Examples of minerals that are not gems:

  • Gypsum, mica (not durable)
  • Milky quartz (not rare)
  • Hornblende (not beautiful as a gem)

When you look at a piece of gem jewelry, consider how these factors came together when you admire its beauty!