This content was first published on IGR – Italian Gemological Review no. 20 in 2025. The information provided here is therefore current as of the original publication date.
In recent years, the aquamarine market has witnessed a significant surge in prices, particularly for gems of the “Santa Maria” variety. Known for their unique deep blue intensity, these aquamarines were originally mined in the Santa Maria de Itabira region of Brazil and are considered the most valuable. Today, high-quality aquamarines can command prices ranging from $500 to $700 per carat for larger stones.
The depletion of Brazilian reserves has led the market to accept similarly characterized gems from Mozambique and other regions under the same designation. This qualitative attribute has long been debated within gemology, prompting institutions like the Asian Institute of Gemological Sciences (AIGS) to establish precise standards of color and saturation for a gem to be classified as “Santa Maria”.
In this context, the geographical origin of this beryl variety emerges as a highly relevant topic. A study conducted by Shiyuan Cui, Bo Xu, Jiaqi Shen, Zhuang Miao, and Zixuan Wang at the China University of Geosciences examined aquamarines from three different regions: Koktokay (China), Minas Gerais (Brazil), and Namaqualand (South Africa). Published in the journal Crystals, the research employed advanced spectroscopic, chemical, and mineralogical analysis techniques to compare the gems from these areas.
Spectroscopic analyses, in particular, revealed significant differences among the samples:
- Minas Gerais aquamarines are characterized by high transparency, intense blue color, relatively low iron and sodium content, and weak blue-white fluorescence under UV light.
- Koktokay aquamarines exhibit a more complex chemical composition with abundant Fe2(OH)4, resulting in a lighter blue-green hue.
- Namaqualand aquamarines stand out for their elevated scandium content and higher saturation of deep blue, suggesting a greater presence of sodium and potassium in their structure.
The study also utilized advanced techniques such as Raman spectroscopy and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) to analyze the chemical compositions of the gems in detail. The findings demonstrated a strong correlation between alkaline element content and color saturation. Notably, Namaqualand aquamarines exhibited a distinctively high scandium concentration (up to 574 ppm), setting them apart from those originating from other regions.
These advanced techniques provide a powerful tool for distinguishing aquamarines from different mines, ensuring the quality and authenticity of the gems. This, in turn, bolsters their appeal in the international market, where demand continues to grow.
The full article is available at the followinga web address: https://www.mdpi.com/2073-4352/13/10/1478
Gem News published on IGR – Italian Gemological Review #20 – Winter 2024/25
