The magic of gemstone inclusions
We love the fascinating and individual nature of the gemstones we work with.
Here, founder and designer Jordan explores why he finds inclusions so bewitching - and what they mean for your jewelry…
What are gemstone inclusions?
“One of the reasons I love working with gemstones is for their multitude of colors and inclusions. Almost every gemstone is unique.
Inclusions are internal characteristics - features beneath the surface of the stones - which are created by the conditions under which the stone was formed and the elements present within it.
Inclusions are like internal blemishes in the structural makeup of the stone. These can include material that has been trapped within the stone during its formation, gas-filled bubbles or liquid, or marks from pressure and heat like fractures, small lines, or dots.
The geological growth environment of marble-hosted rubies from Myanmar (left) is reflected in their internal features, such as calcite inclusions (right). Photos by Robert Weldon (left; courtesy of William F. Larson) and Nathan Renfro (right; field of view 1.44 mm).
For some stones like diamonds, smaller and fewer inclusions are desirable. The clarity of a diamond is determined from the amount and visibility of inclusions, varying from ‘included’ to ‘flawless’.
We use a grade of diamond that requires magnification to see inclusions, very small marks deep within the stone.
Small transparent crystals form clusters in a Vietnamese spinel. These tabular crystals are transparent and doubly refractive, but their host's morphology has been forced upon them, a characteristic John Koivula has dubbed "philoxenism." Dark field illumination. Photos: E. Billie Hughes
Inclusions in colored gemstones
When it comes to colored gemstones, however, their inclusions can actually be what makes them so beautiful and so special.
With many colored gemstones, inclusions can be seen by the naked eye, creating beautifully unique colors and patterns within them.
Inclusions quite literally represent the chemical processes the stones have undergone - the time taken, the pressure and the heat that the earth has put on them. They are reflections of their very formation and the sheer effort - dare I say magic - that has gone into creating each stone over thousands of years.
Because inclusions come about from a variety of different conditions and factors, no stone will have the same inclusions. To put it simply, it means that every stone is completely unique.
Inclusions of insects entombed in amber, such as these two wasps captured in an eternal embrace, offered ancient naturalists a clue to the geological origins of this gemstone. Photomicrograph by John I. Koivula.
Personality & individuality
Imagine inclusions as a fingerprint of a stone. Each line, ridge, and pattern is completely unique. This has both practical and aesthetic implications.
Practically, inclusions can be used to identify your stone. For example, if you’re getting a gemstone report for insurance purposes or to know the origins of your stone, inclusions are what gemologists use to identify your gemstone, often mapping out the inclusions on a report.
Emeralds from mica-rich schists, such as Russian emeralds (left), display inclusions that give away their geological origins, such as fields of dark mica platelets (right). Photos by Robert Weldon (left; courtesy of R.T. Boyd Limited) and Nathan Renfro (right; field of view 2.04 mm).
The same gemstone type from different countries will have different inclusions, due to the different chemical make-up of the land under which they were formed. The right equipment can use this information to trace the origin of the stone.
For instance, a ‘wispy horse tail’ inclusion often appears in garnets, looking like trails of light shooting stars gliding through the stone. This type of inclusion also tells us that the origin of the stone is Russia. I find it incredible a stone’s marks can tell us so much about its history and identity.
What types of inclusions are there?
There are thousands of types of inclusions, but some of the most common are;
- Pinpoints - tiny black dots
- Feathers - tiny cracks that resemble a feather
- Crystals (tiny minerals or even tiny bits of diamonds that became trapped in the crystal as it formed)
- Needles - long, think lines, usually white
- Clouds - small clusters of pinpoint inclusions, which together look like a cloud)
- Twinning wisps - a little like stretch marks, these are mixes of crystals, clouds, feathers and pinpoints
- Indented natural - looks like a chip beneath the surface of the stone
- Internal graining - waves or lines within the diamond, when the stone has formed or grown slightly unevenly
Inclusions really tell us a lot about the way a stone was formed and what it went through beneath the earth’s crust.
A web-like fingerprint creates a maze-like pattern in this spinel from Vietnam, observed with darkfield and diffuse fiber-optic illumination. Photomicrograph by E. Billie Hughes; field of view 5 mm. Courtesy of Vitalit Gems.
Can inclusions be a bad thing in a gemstone?
Of course, there are some inclusions to watch out for.
Surface breaking inclusions can make the stone less hard-wearing than it should be, and too many large inclusions can also create concern for durability.
One of the reasons emeralds are so special and valuable is because of their frequent and beautiful inclusions, sometimes referred to as ‘jardin’ thanks to their mossy appearance.
However, this is also what makes emeralds require a little extra care than other precious gemstones, because their inclusions can make them a slightly more fragile stone.
Left: Magnesium-rich spinel often forms in impure marbles where the magnesium-rich mineral dolomite is present. Right: These spinels contain inclusions where carbonate minerals are more likely to be dolomite than calcite, as seen in this dolomite-filled negative crystal. Photos by Robert Weldon (left) and Nathan Renfro (right; field of view 1.30 mm).
SKYDOG’s take on gemstone inclusions…
There are plenty of jewelry aficionados who desire their gemstones clear and perfect - and I too always appreciate a dazzling, eye-clean diamond or scintillating sapphire!
But I also love gemstones with a little personality. Inclusions are what create the stunning patterns within some of my favorite stones, such as the shifting colors and milky-way markings of a lapis lazuli or turquoise.
Recently I’ve been working with using large pieces of gemstones on the face of my oversized men’s signet rings. The space this provides means you can really see the whirlpools of inclusions within the stone.
There’s an incredible feeling that earth history is dancing beneath the surface of your stone when you look at a gorgeously included gemstone.
And being able to wear a piece of earth history is just… well, magic.