Red corundum is called ruby, blue corundum is called sapphire, and all other colours are called fancy sapphires. A high density of ~4.0 g/cm 3 (most silicate minerals are ~2.6 g/cm 3) results in corundum occurring in secondary placer deposits and recoverable by panning methods, similar to how you would recover placer gold.Ĭorundum comes in all colours of the rainbow but is most commonly found as opaque crystals with dull colours. It has no dominant cleavage and fractures in a conchoidal manner. It has a hardness of 9 on the Mohs scale, making it one of the most durable commercial gemstones. There is a rainbow of Corundum waiting for you.Lesson 17: Corundum Mineralogy and Gemology What is Corundum and What are its Basic Qualities?Ĭorundum is an aluminum oxide that commonly forms hexagonal barrel-shaped prisms that taper at both ends or as thin tabular hexagonal plates.
This unique wearability factor, combined with their rarity and brilliant colors make rubies and sapphires some of the most valuable gemstones. Because rubies and sapphires are so hard and resistant to scratching, they make great choices for all types of jewelry exposed to everyday wear. On the Mohs scale (gemstone hardness scale), Corundum has a hardness of 9, second only to diamond with a hardness of 10. The scientific definition of hardness in gemstones refers to its ability to resist scratching, and nothing more. The word “hardness” in gemology differs considerably from its everyday usage. The hardness of a gemstone is a very misunderstood property. These little beauties, referred to as “Yogo Sapphires,” have come across my desk many times. While Rubies and Sapphires from Sri Lanka and Myanmar often appeal to those with an exotic nature, the Vortex mine in Montana, is a great American source of Sapphires, which it produces using green mining techniques. Are There Sapphire and Rubies born in the USA? You betcha It is now legal to import all gemstones, including ruby and jadeite, from Myanmar. On October 7th, 2016, President Obama signed an Executive Order, effectively removing all sanctions on the importation of gemstones from Myanmar. At one time importing gems from Myanmar was illegal due to human rights abuses. Ceylon sapphires come from Ceylon (even though the country is now known as called Sri Lanka).īurmese stones originate from…you guessed it: Burma, now called Myanmar.
Rubies and sapphires can also be categorized by their origin.
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