TOPAZ

Red and pink topaz varieties, including imperial topaz (medium reddish orange to orange-red color), are the most rare and valuable.

Topaz from in the orthorhombic crystal system. Many topaz crystals are elongated, they’re often cut as long ovals, pears, or emerald cuts.

Because of its basal cleavage, topaz requires special care in cutting, polishing, mounting, and wear.
Often set stone in protective mountings

IMPERIAL, RED, PINK, AND YELLOW-TO-BROWN TOPAZ

COLORLESS AND BLUE TOPAZ

Topaz is commonly colorless, but treatment can produce a blue color.

TOPAZ SOURCES AND MARKETS

  • The Ouro Preto area of Brazil is the world’s major commercial source of imperial and red topaz.
  • At many Ouro Preto mines, yield of facet-grade imperial rough is small

TOPAZ TREATMENTS

Trace Elements

  • Chromium --> Natural pink, red & violet
  • Color centers --> Yellow, brown & blue
  • Color centers & Chromiun --> Orange

Pegmatits Rock, huge crystals are found in cavities & pockets.

The definitions of imperial topaz can vary
widely, usually is medium reddish orange to orange-red color.

  • “sherry topaz”/Precious topaz: orange-to-yellow and brown topaz.

Golden or yellow topza is much more abundant than imperial topaz, therefore less valuable

Since the 1970s, treatments have brought blue topaz to a broad market.

  • “London blue,” “Swiss blue,” “super blue,” “maxi blue” --> darker blues
  • “sky blue” for paler hues
  • In general, darker blue hues cost slightly more
  • Most fine-quality imperial topaz crystals are mined in the Ouro Preto area of Minas Gerais in Brazil.
  • Highly prized red topaz is also mined primarily in Ouro Preto. Miners find various blends of red and purple or red and orange.

Pakistan—Ghundao Hill, near the town of Katlang—supplies gem-quality, naturally pink to red topaz

  • “cyclamen pink” - the most prized pink from Pakistan, called faintly violet

Brazil and Sri Lanka are the most significant sources of treatable colorless topaz

Most topaz mined in Brazil is cut in Brazil

Topaz treatments commonly involve heating or a combination of heating and irradiation, to create or change color in many topaz varieties

To create various shades of blue, treaters start with colorless or very light blue topaz and use one of several kinds of radiation, followed by heating.
The resulting blue color is permernant

  • If yellow to reddish brown topaz contains chromium, careful heat treatment can produce a pink color.
  • To create highly saturated pinks, treaters must start with highly saturated yellow to reddish brown colors.

Heat treatment must be carefully performed because topaz is sensitive.

Stones that remain radioactive after treatment must be quarantined for three months to a year to allow the radiation to dissipate.

Blue topaz is a mass-market gem, price and uniformity are important considerations for buyers of treated blue topaz.

Another treatment involves coating colorless topaz with a microscopic layer of a metallic oxide compound, adds a metallic luster but not durable