Gemstone & Jewelry Blog by Dragon Dreams Jewelry, LLC

April 6, 2015

How hard is it? A simple guide to Mohs’ Scale

Filed under: General Information — Tags: , , , , , , , — dragondreamsjewelry @ 8:52 pm

Gemstones and mineral specimens have many properties.  One that is particularly important for jewelry is hardness.  Why? A stone that is soft should not be used in an unprotected setting or in a piece that is likely to be bumped.

For example, I had a lovely opal ring with four opal cabochons in prong settings.  Not realizing at first how fragile opal can be, I wore the ring regularly.  It didn’t take long before I’d chipped one of the stones.  I was slightly more careful with it but still managed to chip a second stone and lose that first one (as it was loose in its setting).  Fortunately, we were able to match up the opal, cut and polish new cabochons and restore the ring completely.

For stones that are below 7 on the Mohs’ hardness scale, dust can do some damage if rubbed into the stone as quartz particles are fairly common in dust.  To help identify how hard a stone is, there is a “simple hardness tester” that can be used as a guide and to provide an idea of what the various scale values mean along with an example in parenthesis[1]:

  • 1 (talc) and 2 (gypsum): can be scratched with a fingernail
  • 3 (calcite): can be scratched with copper coin
  • 4 (fluorite): easily scratched with knife
  • 5 (apatite): can be scratched with knife
  • 6 (orthoclase): can be scratched with steel file
  • 7 (quartz): scratches window glass
  • 8 (topaz), 9 (corundum), 10 (diamond) : no simple test 

I would not recommend actually trying any of the scratch tests on finished stones but rather use the information to help understand what the various Mohs values represent.  Note that the scale is relative, so that the difference between a 4 and 5 on the scale is not the same as the difference between 9 and 10.

[1] Gemstones of the World: Newly Revised & Expanded Fourth Edition by Walter Schumann, p20 (based on the table “Relative and Absolute Hardness Scale”)

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November 18, 2012

Featured stone: fluorite

Fluorite’s name derives from the Latin fluere, “to flow”.   It “melts more easily than other minerals and was once used as a flux.”  [1]

Fluorite, sometimes called fluorine, fluorospar or fluorspar, can be found in a variety of colors: bright golden yellow, bluish green, rose-pink, blue, green, purple, colorless, and in a mixture of any of these colors.  Fluorite can be transparent or translucent – or anywhere in between.  With a Mohs hardness of 4, this stone is somewhat fragile, brittle and can be damaged easily.

Because the stone is so soft and scratches easily, cleaning fluorite is best done with a soft dry cloth (like a chamois) or with some cool water and a soft cloth.  Do not use warm or hot water on fluorite as this will damage the luster.  The beautiful colors of fluorite can fade if exposed to prolonged intense sunlight so be careful to store these stones in a cool, dark place.   To protect your fluorite jewelry when not in use, also store it apart from other stones, wrapping it in a soft cloth to provide additional protection from scratching or chipping.

One of the interesting features of fluorite is that it usually glows (fluoresces) under black or ultraviolet light – likely caused by yttrium and other trace impurities in the stone.

Fluorite may be irradiated or heated in oil to deepen the color.  It may be impregnated with a resin or polymer to strengthen the stone.  Cabochons are sometimes capped with clear quartz to protect the stone against scratches or being chipped.  All treatments should be disclosed by the seller.

Fluorite (sometimes called “the genius stone”) has a myriad of metaphysical properties associated with it, including:

  • stimulates third eye
  • increases wisdom and the power of discrimination
  • aids the advancement of the mind, concentration, and meditation
  • cleanses aura
  • promotes self-love
  • powerful healing stone
  • grounds excess energy
  • boosts comprehension
  • promotes spiritual and psychic wholeness and development, truth, protection, and peace

Chakras: vary by color but include heart (green), third eye (purple)

[1] The Jeweler’s Directory of Gemstones by Judith Crowe, p.108

See beautiful jewelry like this for sale at our website – www.dragondreamsjewelry.com

Fluorite wrapped in Sterling Silver

 

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