Gem-quality pink fluorite from Planggenstock, Switzerland: chemical and physical properties and a comparison with pink fluorites from other localities

When it comes to the geographic origin of gems, curiously enough, historians sometimes put forward p

A newly observed variety of faceted transparent brown sapphire has recently entered the gem market,

Jade or "Fei Cui" are trade names for a stone that typi- cally contains only one or more main minera