Amethyst: Power to the Purple!


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).


  • 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.


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!



  • 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.



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)                               

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):                                                                      


Hematite, Imitation Hematite and Disclosure


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.


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.


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!

Gold, part 2 of 2

Gold, Part 2 of 2: Platings

The Federal Trade Commission (FTC) provides guidelines for correct terminology when describing gold used in jewelry.  These guidelines apply only to items made in the United States.  Other countries may have different guidelines.

Gold Filled (also called gold overlay):

Gold filled jewelry is made by using heat and pressure to apply a layer of karat gold to a less costly base metal.  The surface layer of karat gold on gold-filled items is usually 10kt, 12kt or 14kt. To know the thickness of the layer, look for a fraction, such as 1/10 or 1/20. Examples:

  • 1/10 10kt GF: 1/10 of the total weight must be 10kt gold.
  • 1/20 12kt GF: 1/20 of the total weight must be 12kt gold.

Gold fill is 50 to 100,000 times thicker than regular gold plating, and about 17 to 25,000 times thicker than heavy gold electroplate.

Gold Vermeil (pronounced vehr-MAY):

Gold vermeil is a plating of karat gold over sterling silver. The FTC guide states “An industry product may be described or marked as “vermeil” if it consists of a base of sterling silver coated or plated on all significant surfaces with gold, or gold alloy of not less than 10 karat fineness, that is of substantial thickness  and a minimum thickness throughout equivalent to two and one half (2 1/2) microns (or approximately 100/1,000,000ths of an inch) of fine gold.”

Gold Plated:

Gold plating is a very thin deposit of gold (about 1/1,000 – 1/1,000,000 of an inch).  Heavy gold electroplate might be 2 or 3/1000s of an inch thick (this can also be written as 2 or 3 mils).  Many gold-plated items have a white nickel plate under the final gold plate.  Gold plating can be worn away relatively easily.


Photo by Paolo Ciccone

Mochi’s Gifts Jewelry:

I use gold-filled beads, clasps, and ear wires for my designs. This is the best way to provide you with a durable, high quality piece of jewelry featuring gold components at an affordable price. I also use gold vermeil beads to get the beautiful color of high karat gold without the high cost.

The earrings pictured here feature gold-filled earwires and headpins (the straight wires the beads are on), gold vermeil puffed square beads, and garnets.

Thanks for reading!


Sources for information on gold used in jewelry:



Gold, part 1 of 2

Today I’m going to provide some information on gold used in jewelry including karat gold, gold vermeil and gold plating. Much of this information was initially confusing to me which is why I chose to learn more about it. I hope you find it interesting and informative and that it improves your confidence when you purchase jewelry!

Did you know that the Federal Trade Commission (FTC) publishes guidelines for precious metals and jewelry? Gold fineness markings and descriptions have very specific definitions under U.S. law, but remember, products purchased in other countries may follow different legal requirements. And, unfortunately some sellers may purposely misrepresent their products’ purity.   See the sources at the end of this posting for more information.

Gold, part 1 of 2: The Basics

Gold has been used for jewelry for centuries and has been found in archaeological sites in Egypt and South America as well as in many other areas of the world.

Karat (kt) Gold:

Pure gold is 24 karat (kt), meaning 24 out of 24 parts are gold, in other words, “pure” gold. 24kt gold is very soft and not practical for jewelry as it is too malleable. To make it stronger, gold is alloyed with other metals.   Alloy metals may include copper, silver, nickel, zinc, tin, palladium and/or manganese. These alloys can also give the gold different colors (yellow, rose, white and green). In addition, the higher the percentage of the alloy vs. gold, the lower the cost of the finished metal. See the table below for the conversion from karat to gold content.

Common karat (or fineness) values seen in jewelry Approximate % gold
24 100
22 92
18 75
14 58
12 50
10 42

I have often been asked whether white or yellow gold is “better”. 14 kt white gold has the same amount of gold as 14 kt yellow gold. It is the percentage of gold that matters, not the other metals used to provide durability and color.

Next week, Gold, Part 2 of 2: Platings.

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 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. (

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!