Martin Rees, Jeweller and Pawnbroker

Amethyst geode

Crystals have formed in this Amethyst Geode

Quartz Crystals


You can't dissolve quartz in water (otherwise drinking glasses wouldn't last).  But if the water is superheated, i.e. heated with no way for the steam to escape, as in a steam boiler, the water can't boil and becomes very hot and with a high pressure, then it will dissolve quartz.  And that happens deep inside the earth.  The pressurised water finds cavities; then cools, depositing the quartz as crystals.  The geode above is a typical example.  Note how the crystals have partly filled the cavity.  The crystals changed in colour as the impurities in the solution varied.

Composed of silicon dioxide, quartz is very common, although gem quality crystals are less common.  In its pure form it is colourless; the colours are caused by impurities - often trace amounts of metals.  Walk on a beach, and you are walking on broken up bits of quartz (we call it sand).
Quartz has a strange electrical property.  When squeezed, it produces an electric charge.  Or when a charge is applied to a lump of quartz, it bends.  If we keep switching the charge on and off, the crystal will start to oscillate; that's the basis of quartz watches.
Because quartz is so useful, crystals are synthesised by man, and that includes gems.  However the genuine crystals are so cheap that there is little risk of problems here.

Caring for Quartz

Quartz is easy to clean;  you can safely soak it in water, and clean the stones with detergent.  I have found these stones do benefit more than most from frequent cleaning.  The transformation when a stone is cleaned can be amazing!  Do remember that quartz is the main constituent of sand, soil and also a part of household dust.  So all these things can scratch the stones, because the stones are no harder than the grit.  Avoid wearing these stones in rings when doing rough work - anyway rough work also scratches gold and silver.

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The symbol of sincerity.  The Egyptians placed amethysts on the body of the deceased.  It was believed to prevent drunkenness (the name comes from the Greek Amethystos, meaning non-intoxicating).  Amethyst was supposed to protect against spells, and bestow business success and intelligence.  There are many legends attached to this stone; I suspect it was the most popular variety of quartz in ancient times. Today it's the February birthstone.

Rock Crystal

Rock Crystal is colourless quartz (i.e. pure quartz), and was believed by the ancient Greeks to be fossilised ice.  I'm sure we're all familiar with crystal balls - that's just one use of Rock Crystal.
Although rock crystal was used in the past as a cheap imitation of diamond, it lacks the dispersion (i.e. it doesn't split light so well into the rainbow colours you see in a diamond); these days there are better man-made diamond substitutes.  Enjoy rock crystal for its own qualities  It's natural, and often has appealing inclusions.  I love large crystals, they make great ornaments.


This stone comes in a range of shades, varying from pale yellow through orange.  Inclusions are rare, most stones are totally transparent.  Most Citrine sold these days is heat-treated Amethyst.  The treatment is permanent.  Citrine is the alternate November birthstone.

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Amethyst with inclusions

Interesting 'tiger stripe' inclusion in Amethyst.  It's beautiful, in addition it confirms this gemstone is natural; this flaw never occurs in synthetic stones.

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