“Color is a power which directly influences the soul” Wassily Kandinsky
Delicate pink hues of Rose Quartz and Pink Opal are heartwarming. Green shades of Aventurine and Malachite are inspiring. Yellow splashes of Citrine infuse your senses with energy and optimism.
The truth is... to a great extent it’s color that defines gemstone personality and its perceived properties.
But what defines the color itself?
What makes Turquoise blue, Amethyst purple and Ruby red?
Let’s explore the mysteries of colored gemstones. Promise, it will make you adore your gemstone jewelry even more.
Color is the interface between light and matter.
Poetically speaking, color is the interface… between subtle reality of light and the world of solid matter. It’s the language that Mother Nature uses to reveal what is hidden inside, to give us a clue what the substance is made of and much more…
Scientifically, color is a result of light rays interacting with a physical object. No light – no color, right? You won’t see colors of objects in a completely dark room.
Every school student today knows (hopefully!) that white light we see is a combination of electromagnetic waves of different wavelengths. White light consists of light rays of all colors – full visible spectrum – red, orange, yellow, green, blue, indigo, and violet – where red light waves have the longest wavelength and violet the shortest.
Splitting the light is a classic example of white light that goes through a prism – a solid glass triangle. The glass changes (refracts) the direction of the light as it goes through the prism splitting it into the spectrum so we can see light rays of different colors.
This is how the prism splits white light into its spectrum of colors and how rainbows work.
When white light passes through the crystal (or any physical object) some color rays get absorbed (trapped) within the gem while others get refracted – changing the direction as they pass through the gemstone. When one or more of these color rays are absorbed, the remaining light emerging from the gem is colored.
What we see is the wavelengths of light reflected back to the viewer and we perceive them as color.
So a red colored crystal absorbs all rays of spectrum apart from the red, that’s why we see the red color. Black gemstone absorbs all wavelengths (all colors of the spectrum) not reflecting any light so it looks dark to us. Conversely, white rock doesn’t absorb any light and reflects all color rays back.
Therefore the ability of each gemstone to absorb particular light wavelengths defines its color.
That’s how beautiful minerals get their colors as we see them.
Apart from absorption the presence of trace elements, different inclusions and gems’s chemical structure itself can affect the color we see.
Idiochromatic gems are, so-to-say, ‘self-colored’. They mostly occur in only one color, which is inherent in their chemical make-up. Idiochromatic crystals never found colorless because the elements that cause color are essential part of gem’s chemical structure.
Malachite (Cu₂CO₃(OH)₂) is always green due to Copper (Cu) that plays an essential part in its chemical formula. However, in other idiochromatic gems Copper may produce different colors. Copper causes red color in the rare gemstone Cuprite (Cu₂O) and blue color in Turquoise (CuAl₆(PO₄) ₄(OH)₈·4H ₂O) just because there are other factors that affect the color we see.
Example: Peridot ((Mg,Fe)₂SiO₄) an iron magnesium silicate, obtains beautiful green color as a result of its iron (Fe) content.
Allochromatic gems are colored by trace elements in their structure. These oh-so-wanted “impurities” are not essential for gem’s chemical structure, yet they “run the show” and play a key role in coloration.
Let’s look at the wonderful Beryl gemstone family which includes green Emerald, pink Morganite and blue or green-blue Aquamarine. The whole family shares the same chemical formula (Be₃Al₂Si₆O₁₈). But what makes each family member look so unlike its siblings?
It’s different ‘guest’ elements that create all these color variations. Without these ‘impurities’ beryl would be colorless. In fact, it would become a much more modest and less prized version of itself known as Goshenite (Be₃Al ₂SiO₆).
Rutilated Quartz is a variety of Clear Quartz which contains tiny inclusions of another mineral – Rutile. These golden inclusions grow naturally inside clear Quartz if iron oxide content is high.
Most popular gemstones used for jewelry – like Quartz, Topaz, Tourmaline – are allochromatic.
Example: Amethyst is colorless variety of Quartz (SiO₂) made purple by traces of iron (Fe).
Parti-colored gems display different colors within the same crystal. Parti-coloring can be caused by changes in the chemical medium in which the crystal has grown. Divisions between the colors can be abrupt or gradual.
Example: Watermelon Tourmaline, Parti-Sapphire, Ametrine.
Parti-Sapphire is a fusion of Blue and Yellow Sapphires with absolutely natural color zoning, which is impossible to replicate in lab grown sapphires. It’s iron (Fe) inclusions with only a single electron difference that make the crystal blue (Fe₃+) or yellow (Fe₂+) in different zones.
Color of pseudochromatic gemstones is not a result of their chemical formula or inclusion, it is caused by physical effects such as the play of light.
When light passes through a crystal, colors can be absorbed differently in different directions – as a result the gemstone changes its colors when viewed from different angles.
Example: Labradorite.
Learn more about tantalizing colours of Labradorite and its use in jewelry.
| Blue gemstones | Pink gemstones | Purple gemstones | Green gemstones | White gemstones |
| Black gemstones | Golden-Yellow gemstones | Brown gemstones | Transparent gemstones | Multicoloured gemstones |
Athena Aegis necklace with Montana Agate gemstone and Dancing Orbit necklace with Rutilated Quartz gemstone.
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Lara Gems
Author
Gemstone Strategist and Founder of Gems In Style Jewellery