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TOPAZ (TOPAZ TREATMENTS (Topaz treatments commonly involve heating or a…
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
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
COLORLESS AND BLUE TOPAZ
Topaz is commonly colorless, but treatment can produce a blue color.
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
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TOPAZ TREATMENTS
Topaz treatments commonly involve heating or a combination of heating and irradiation, to create or change color in many topaz varieties
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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.
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
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.