Precious and Decorative Stones

2023: No. 2 (112) CONTENTS

AN UNIQUE VARIETY OF FLUORITE "BLUE JOHN"

К. Tatarintseva
State Gemmological Centre of Ukraine

О. Belichenko
State Gemmological Centre of Ukraine

Yu. Gayevsky
State Gemmological Centre of Ukraine

Yu. Ladzhun
State Gemmological Centre of Ukraine

Language: Ukrainian

Precious and Decorative Stones. No. 2 (112), 2023: 12–17

Abstract
Information is provided on "Blue John", a unique variety of fluorite with rhythmically zoned colours of purple or violet, blue, yellow and white, mined in the Peak District, Derbyshire, England. The history of extraction and use, gemological properties, diagnostic characteristics are considered. The results of gemological research of the sample of "Blue John" fluorite at the State Gemological Centre of Ukraine are presented. According to the results of the IR spectrum and fluorescence in the short-wave range (225 nm) on the "DiamondView™" device, signs of treatment by impregnation with epoxy resin were established.

Keywords: fluorite, "Blue John", diagnostic characteristics, gemological expertise.

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