Brazilian Aquamarine & Topaz
World-renowned Brazilian aquamarine including Santa Maria quality, and exclusive imperial topaz from Ouro Preto.
Introduction
Brazil's Minas Gerais state has been the world's benchmark source for aquamarine
since the early twentieth century. The Santa Maria de Itabira district lent its
name to the most prized colour grade: a medium to medium-dark, strongly saturated
blue with minimal green modifier; "Santa Maria" is now applied by the trade to
any aquamarine of equivalent colour intensity regardless of origin. [1]
Minas Gerais pegmatites yield exceptionally large crystals: the Dom Pedro aquamarine,
a 10,363-carat carved obelisk now in the Smithsonian Institution, was cut from a
single Brazilian crystal. Heat treatment to remove the greenish iron modifier is
broadly accepted when disclosed. [2]
Brazil also holds geographic exclusivity on imperial topaz at Ouro Preto, Minas
Gerais, the world's sole commercial source of orange to pink-red topaz. Fine sherry
to pink material commands $1,000–5,000 per carat or more; declining production has
steadily firmed prices. [1]
Brazilian Aquamarine
Premier aquamarine production:
Sources
- Minas Gerais: Primary source; multiple deposits
- Santa Maria de Itabira: Famous intense blue origin
- Bahia: Additional production
- History: Major source since 1910
Characteristics
- Colour: Light to medium blue; some greenish
- Santa Maria: Term for finest deep blue
- Clarity: Often excellent
- Sizes: Notable for large crystals
Santa Maria Quality
Famous Aquamarines
Notable Brazilian specimens:
- Dom Pedro: 10,363 carat carved obelisk (Smithsonian)
- Hirsch Aquamarine: 109.9 carat faceted gem
- Marta Rocha: 134,000 carat rough crystal
- Many museum-quality crystals from Minas Gerais
Aquamarine Treatment
Enhancement considerations:
- Heat treatment: Common; removes green modifier [2]
- Purpose: Produces purer blue colour
- Acceptance: Generally accepted practice
- Detection: Difficult to determine
- Disclosure: Variable in trade
Imperial Topaz
Brazil's exclusive variety:
Ouro Preto Source
- Location: Ouro Preto, Minas Gerais
- Exclusivity: Only commercial source worldwide
- Geology: Weathered deposits in clay
- Character: Unique formation conditions
Colour Range
- Orange: Most common imperial colour
- Sherry: Reddish-orange ideal
- Pink: Most valuable; very rare
- Red: Extremely rare; highest values
Characteristics
- Pleochroism: Shows colour variation with direction
- Clarity: Typically eye-clean
- Hardness: 8 (excellent for jewellery)
- Lustre: Vitreous; excellent brilliance
Imperial Topaz Rarity
Imperial Topaz Value
Market position:
Pricing
- Premium over other topaz colours
- Orange: $500-2,000/ct for fine stones
- Sherry: $1,000-5,000/ct range
- Pink: $2,000-10,000+/ct
Value Factors
- Colour saturation most important
- Pink tones add significant value
- Clean material preferred
- Origin documentation adds confidence
Other Topaz
Beyond imperial:
Blue Topaz
- Colourless topaz commonly irradiated/heated
- "London Blue", "Swiss Blue" created
- Lower value than natural colours
- Major production for treatment
Treatment Note
- Most blue topaz is treated
- Pink topaz may be heated from yellow/orange
- Imperial colour generally natural
- Disclosure required for treated material
References
- ↑ 1. Schumann, W. (2009). Gemstones of the World (4th ed.). Sterling Publishing. ISBN: 978-1-4027-6829-3.
- ↑ 2. Read, P. (2014). Gemmology (3rd ed.). Butterworth-Heinemann. DOI: 10.4324/9780080507224.