eli5 What determines whether a gem is a sapphire, ruby, emerald, diamond, etc if those gems don’t necessarily have to be the most common thought color? For example, sapphires can be colors other than blue. What’s the difference between a red sapphire and a ruby?

Question

eli5 What determines whether a gem is a sapphire, ruby, emerald, diamond, etc if those gems don’t necessarily have to be the most common thought color? For example, sapphires can be colors other than blue. What’s the difference between a red sapphire and a ruby?

In: 5800

Answer 1

Lots of similar answers yet nobody touching on history. By and large the type of gem IS determined by its appearance, originally.

* Sapphire comes from Sanskrit or a related language and means ‘dark stone’. The word is so old blue wasn’t its own color, yet.
* Ruby means ‘reddish’ in the original Latin.
* Emerald meant ‘shining/flashing precious stone’ in some Semitic language.
* Garnet is related to ‘pomegranate’, a fruit with translucent red flesh.
* Amber is named after the stones formed in whale guts.
* Aquamarine should be obvious.
* Lapis is Latin for ‘stone’ and lazuli is related to ‘sky blue’ in a bunch of languages, including their modern descendants like Portuguese (azul) though in most the L shifted to an R as in azzurro, azur, azure…
* Beryl and Topaz are named after the places they were found. Bit of a stretch on the meaning of ‘appearance’.
* Some exceptions: Diamond comes from Ancient Greek ‘unbreakable’, Amethyst from ‘not drunk’ because they thought it prevents intoxication and Opal is basically a really really old word for ‘above/superior’, i.e. something more precious than the common stone, a precious stone if you will.

Waaay later we figured out some of these are more or less the same thing and some aren’t the same thing at all. Because people naming things like order stuff got redefined. Unless a specific entity had a proper name. The Black Prince’s Ruby came into possession of the British in the 14th century. 300 years later it turns out to be a spinel as chemistry progressed.

We did the same with animals when we refined anatomical classification and finally switched to genetics. Old texts like Greek myths or the Bible refer to whales as fish. Cheetahs and cougars aren’t big cats anymore. But a variation of ‘fish buzzard/eagle/hawk’ is used in some languages while ospreys are very much their own family.