It’s green, it’s red, it’s blue it’s clear- it must be emerald, ruby, sapphire or diamond.

It may interest readers of our master classes to learn that until the early 1700s that anything red was a ruby and blue was a sapphire and anything clear was a diamond. Today’s gemmologist is familiar with the refractometer, spectroscope and specific gravity formula for dividing  gems into the 7 crystal systems and their scientific families of corundum, beryl, diamond etc. The early gem trader knew enough to know that there was a difference in the hardness between gems and that some gems “felt” heavier than others and that some “emeralds had a better green than others and that some diamonds where better than others because they were harder and the some rubies where redder than others but the early gem trader relied on no or poor science to back up their assertions. We know for instance that what we call today lapis lazuli was called sapphire by the ancient Greeks and Romans. A lot of the modern gem deposits weren’t even known before the 1700s. The most famous misnomer of a gem is in the British Imperial State crown. The “Black Prince’s Ruby” is a red Spinel. 

- Ronnie Bauer