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Winter 1990, Volume 26, Issue 4 (sold out)

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Gem News


DIAMONDS

  • De Beers announces world's largest synthetic diamond crystal
  • China-cut diamonds sold in Singapore
  • Guyana mining development

COLORED STONES

  • Possible foreign participation in Afghan mining
  • Novel assembled stone
  • Black coral industry on the Mexican Caribbean
  • Update on sapphire mining in Kanchanaburi
  • Peace pact for Colombian emerald region
  • Unusual color-zoned garnet
  • Heavy liquids studied in Australia
  • Black cat's-eye opal
  • Exceptionally large white opal
  • Color-change cobalt spinel
  • Large topaz sculpture
  • Cat's-eye bicolored tourmaline
  • More gems from the USSR?

ENHANCEMENTS

  • Diffusion-treated sapphire update
  • "Rainbow" quartz: A new enhancement
  • Jade "processing"

SYNTHETICS AND SIMULANTS

Appears on pages 300-309

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