EOSC 118 Lecture Notes - Lecture 16: Corundum, Lapis Lazuli, Topaz
Document Summary
Lesson 16 - corundum - parent to rubies and. Learning objectives: describe the basic relationship between corundum and ruby and sapphire. List the historically important ruby and sapphire occurrences. Corundum also gives rise to different gem varieties: ruby and sapphire. These two coloured gemstones are the most important of the coloured stones, and account for more than 50% of global non-diamond gem production. Ruby, sapphire and emeralds make up the big three gemstones. It is hard (h=9), durable, rare, transparent, and vibrantly coloured with a palette of colours. Corundum has been sourced from many areas in the world over many thousands of years. Demand for the gem varieties of this mineral has been steadily climbing, making synthetics, imitations, and treated stones commonplace. In fact, nearly 99% of corundum, be it sapphire, fancy sapphires, or ruby, are heat treated to anneal cracks, intensify colours, and improve clarity.
