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?
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The impurities are what give gemstones their different colors.
Gems have crystalline structures, meaning the atoms appear in a regular, 3D pattern. For instance, aluminum oxide is made of aluminum and oxygen. But if you replace a tiny fraction (around 1% or less) of the aluminum with something else – like iron, titanium, vanadium, chromium, or various other metals – you can get different colors.
In the periodic table, these transition metals produce colors when they oxidize (chemical name for “rust”). You already know that iron becomes orange when it oxidizes. Chromium can be yellow or purple. Titanium can be pink or blue. Chromium can be red. And so on…
Different combinations of metals in different concentrations create a wide variety of colors in these crystals.
The impurities are what give gemstones their different colors.
Gems have crystalline structures, meaning the atoms appear in a regular, 3D pattern. For instance, aluminum oxide is made of aluminum and oxygen. But if you replace a tiny fraction (around 1% or less) of the aluminum with something else – like iron, titanium, vanadium, chromium, or various other metals – you can get different colors.
In the periodic table, these transition metals produce colors when they oxidize (chemical name for “rust”). You already know that iron becomes orange when it oxidizes. Chromium can be yellow or purple. Titanium can be pink or blue. Chromium can be red. And so on…
Different combinations of metals in different concentrations create a wide variety of colors in these crystals.
Gemstones are usually different minerals (although some organic materials are worn as gems in jewelry like pearls and amber) and most of them get their color from structural or chemical impurities that refract light in different parts of the spectrum.
Interestingly enough there’s a pretty large variety of quartz that would include rose quartz, amethyst, citrine, ametrine, jasper, and agate but aside from color I’m not entirely sure what would make those quartz varieties distinct.
Fun fact though: peridots are always green.
Gemstones are usually different minerals (although some organic materials are worn as gems in jewelry like pearls and amber) and most of them get their color from structural or chemical impurities that refract light in different parts of the spectrum.
Interestingly enough there’s a pretty large variety of quartz that would include rose quartz, amethyst, citrine, ametrine, jasper, and agate but aside from color I’m not entirely sure what would make those quartz varieties distinct.
Fun fact though: peridots are always green.
The simplest answer is that the common gem names are applied to whatever people agree to call them. The distinction between a ruby and a sapphire is entirely arbitrary. Why is red corundum called a ruby? Because ruby meant red. Emerald meant a green gem and has been applied to malachite at times. Sapphire May have come from it being sacred to (what would be called) Saturn, probably wasn’t what the Greeks called sapphires, but instead was because they described sapphires as blue. Diamond was called such because it was super hard. All of those gem names came from either observable phenomena or cultural legacies. Not scientific consistency.
Our definitions of what constitutes a ruby ultimately comes down to organizing what different people called recurring groups of minerals. We could get rid of ruby entirely because it’s uniqueness comes from its color and that the name is popular. We could call it a red sapphire and it would probably be more accurate.
The simplest answer is that the common gem names are applied to whatever people agree to call them. The distinction between a ruby and a sapphire is entirely arbitrary. Why is red corundum called a ruby? Because ruby meant red. Emerald meant a green gem and has been applied to malachite at times. Sapphire May have come from it being sacred to (what would be called) Saturn, probably wasn’t what the Greeks called sapphires, but instead was because they described sapphires as blue. Diamond was called such because it was super hard. All of those gem names came from either observable phenomena or cultural legacies. Not scientific consistency.
Our definitions of what constitutes a ruby ultimately comes down to organizing what different people called recurring groups of minerals. We could get rid of ruby entirely because it’s uniqueness comes from its color and that the name is popular. We could call it a red sapphire and it would probably be more accurate.
To add; long (centuries) before atomic theory and the modern understanding of chemistry relating to minerals, or the tools such as mass spectroscopy that can view the chemical makeup of as substance directly, people could tell these stones apart independent of their visual appearance. They tested for hardness by scratching other stones, they measured density and a special variant of density called specific gravity using scales and jars of water. All these properties are unique to each mineral type and were known long before the chemistry.
To add; long (centuries) before atomic theory and the modern understanding of chemistry relating to minerals, or the tools such as mass spectroscopy that can view the chemical makeup of as substance directly, people could tell these stones apart independent of their visual appearance. They tested for hardness by scratching other stones, they measured density and a special variant of density called specific gravity using scales and jars of water. All these properties are unique to each mineral type and were known long before the chemistry.
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.
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.
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