Category: Gem Notes

Pezzottaite

Posted on May 1, 2023 by John J. Bradshaw, GIA GG

Pezzottaite is a mineral species with the formula Cs(Be2Li)Al2(Si6O18). It is named after Dr. Federico Pezzotta from the Natural History Museum of Milan for his work on Madagascar’s granitic pegmatites.

Gem Notes

Hauyne

Posted on March 1, 2023 by Brecken Branstrator, GIA GG

Haüyne is a rare mineral, not often seen as a faceted gem even within the colored stone world. But it’s a material that has resurfaced in conversations on online gemological forums of late, receiving plenty…

Gem Notes

Jeremejevite

Posted on January 1, 2023 by John J. Bradshaw, GIA GG

Introduction: Jeremejevite is not well known among the general public and it is safe to say, it is not a common gem seen or familiar within the gem and jewelry industry. Unlike many gems within the…

Gem Notes

Wulfenite

Posted on November 1, 2022 by John J. Bradshaw, GIA GG

INTRODUCTION Wulfenite is a mineral species crystallizing in the tetragonal system, lead molybdate, with the formula PbMoO4. It was named after the Austrian mineralogist, Franz Xavier Wulfen. Wulfenite is almost always found as thin, tabular crystals…

Gem Notes

Kyanite

Posted on August 31, 2022 by John J. Bradshaw, GIA GG

Kyanite can be extremely attractive as mineral specimens (Figure 1) and is actively sought after by collectors.

Gem Notes

Aragonite & Calcite

Posted on July 1, 2022 by John J. Bradshaw, GIA GG

Just as graphite and diamond have the same chemical composition but crystallize in two different systems, so is the case with aragonite and calcite

Gem Notes

Zincite

Posted on April 26, 2022 by John J. Bradshaw, GIA GG

To complicate matters, zincite can be and has been intentionally synthesized in a laboratory. Many years ago, synthetic zincite was used as semi-conductor crystal detectors in radios before the advent of vacuum tubes.

Gem Notes

Some Interesting Finds in Tucson

Posted on February 28, 2022 by Richard B. Drucker, GIA GG, Honorary FGA

Blue chalcedony is not a gem that the GemGuide normally researches, but in Tucson was a dealer selling Ethiopian blue chalcedony that was of the finest we have seen.

Gem Notes

Brazilianite

Posted on January 3, 2022 by John J. Bradshaw, GIA GG

Faceted brazilianites are definitely not an “off the shelf” gemstone.

Gem Notes

Colorado Rhodochrosite

Posted on November 1, 2021 by John J. Bradshaw, GIA GG

Rhodochrosite has become increasingly popular among collectors and jewelry connoisseurs in recent years. Most

Gem Notes

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