Origins of Turquoise used in Antique and Modern Jewellery

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Origins of Turquoise used in Antique and Modern
Jewellery
B y - https//nigelnorman.co.uk/
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• Turquoise was among the first gems to be
  mined by our ancestors with many historic sites
  now exhausted.
• Hardness and richness of colour are the two
  major factors determining the value of turquoise
  while colour is a matter of individual taste,
  generally speaking, the most desirable is a
  strong sky to robin egg blue. It is rare and
  valuable in finer grades and has been prized as a
  gemstone and ornamental stone for thousands of
  years. Whatever the colour, turquoise should not
  be soft or chalky as it is liable to fade or
  discolour over time and will not hold up to
  normal use in jewellery.

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• The Sinai Peninsula in Egypt is believed to
  be the oldest known Turquoise mine
• An important source of turquoise for at least
  2,000 years has been Persia (now Iran). Persian
  turquoise was used to cover the domes of palaces
  because its intense blue colour symbolised heaven
  on earth. Their deposits are blue naturally with
  the oldest known workings in Nishapur. It is a
  durable turquoise which was used extensively in
  Georgian and Victorian jewellery and remains
  highly valued and sought after for its fine
  colour.

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• Another important source was the Sinai
  Peninsula in Egypt which is believed to be the
  oldest known mines. Here the turquoise is
  typically greener than Persian turquoise.

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• More recently the United States has become a
  significant source of turquoise used Antique in
  modern jewellery. New Mexico was the countrys
  largest producer although it is more or less
  exhausted today. Arizona has more recently been
  an important producer of turquoise with the
  Sleeping Beauty mine producing turquoise of
  unique colour, rivalling the Persian material in
  durability. This mine has now closed increasing
  the value of this turquoise. In general, however,
  American turquoise compared with Persian
  turquoise is of a lower grade with high levels of
  iron which means that greens and yellows
  predominate. It is not very durable requiring to
  be treated or enhanced to be able to be used in
  jewellery.

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• Unfortunately, in common with other opaque
  gems, turquoise has been devalued by the
  introduction of treatments, imitations and
  synthetics. It is therefore important when buying
  turquoise to recognise the difference between
  natural, synthetic and treated turquoise, in
  theory any such treatments which have been
  performed should be disclosed to the buyer.

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• I have a very limited number of turquoise
  pieces but all are with the Persian turquoise
  which to me is the finest colour of them all. The
  two examples in this post are from the early 19th
  century.  https//nigelnorman.co.uk/