How Are Gemstones Formed? Powerful Natural Materials, from Earth to Jewelry

Gemstones — formed over millions of years by Earth’s geologic processes, like cooling magma, plate tectonics, and even erosion  — bring a naturally captivating narrative to fine jewelry design. So much more than luminosity and shine (though we do applaud those qualities), diamonds, emeralds, sapphires, and other gemstones are truly “from Earth, with love.” Each stone tells a story.

“With gemstones, we have a very tangible, cosmic-level piece of history that we get to work with,” says Anna Bario, Bario Neal Principal + Lead Designer. “They’re amazing formations from Earth. It adds depth to our collections and custom designs when you consider the materials and  how long the formation took and how long ago they’ve existed before we hold them.”

A deep appreciation for these Earth-forged rare materials shaped by time is one reason that Bario Neal practices Earth Day principles year-round. The team is dedicated to sustainable jewelry design and has established gemstone sourcing that minimizes, as much as possible, the environmental impacts of mining. Why perpetuate damage to the very origin of these colorless, colorful, and multicolored icons? (Bario Neal has published details about their diligent ethical sourcing of sapphires and emeralds, colored gemstones, Australian diamonds, and Canadian diamonds.) Many clients appreciate Bario Neal’s dedication to crafting jewelry with fully traceable gemstones too. In many ways, traceability — full transparency about where a stone has come from — means making sure that every gemstone’s story is preserved rather than erased. 

“Gemstones represent planetary history,” Anna says. “They are records, of magma cooling slowly over centuries, of what other minerals were present. Some gemstones take millions of years to form, and we find gemstones through mining that are already millions of years old. Sometimes it’s heat and pressure. Sometimes it’s happening in lava chambers. As natural materials, they are small but incredibly potent symbols.” 

How Are Gemstones Formed?

The crystal structure and color of gemstones — the details that define a gemstone’s type appearance — are the result of a geologic process and what minerals were present during formation. Titanium or chromium, for example, can influence the destiny of a sapphire, which is colorless in its “pure” state. A blue sapphire means there was titanium. A red color, which makes it a ruby, is a clue that chromium was on the scene.

If you’ve ever caramelized sugar to make candy, you’ve had a glimpse into the crystallization (solidification) at the heart of gemstone formation. The type of geologic process depends on temperature, pressure, and time, and some gemstones are created by more than one process. 

  • Igneous gemstone creation happens deep underground at extremely high temperatures, in the molten rock of the Earth’s mantle. Massive shifts, like volcanic eruptions, will push the formed gemstones closer to the surface for miners to discover.
    Examples: Diamond, Peridot
  • Hydrothermal gemstone creation leads to stones taking shape as mineral-rich waters begin to cool and crystals form.
    Examples: Tourmaline, Emerald
  • Metamorphic gemstone creation refers to magma pushing through earth and melting rock, which then recrystallizes as a new material under pressure that’s typically generated by shifting tectonic plates.
    Examples: Sapphire, Ruby, Garnet
  • Sedimentary gemstone creation occurs thanks to the sediment in water deposits on Earth’s surface, like rainwater and groundwater, that settle into the cracks and crevices. The minerals present influence the gemstones that form there. For example, turquoise gets its color from copper in water, and opals are formed from a solution of silicon dioxide and water.
    Examples: Opal, Turquoise 

Each geologic process renders beauty in its own style. 

“Softer gemstones like opals aren’t formed under the intense heat and pressure, but they have other qualities,” Anna notes. “That process means they have much more varied surface textures and play of color. Part of their beauty is that they are delicate.”

The “marbled” appearance of Bario Neal’s Sapphire Slice Earrings and Shield Ruby Slice Pendant, Anna says, is another hint at how Earth serves up a stunning variety of gemstone looks. “You can see the crystal formation in them,” Anna says of the inlay pieces. “In the sapphires, you see the white and blue together.”

How Are Gemstones Prepared for Jewelry?

A gemstone’s journey from mine to jewelry collections or custom designed jewelry can take months or years, depending on the source and path. (If you’re custom designing jewelry with heirloom gemstones passed down through your family, that timeline might be centuries.) The three basic stages are: mining to extract rough gemstones, cutting and polishing the rough stones, and handcrafting fine jewelry with polished and cut gemstones. 

Rough Gemstones 

“You can see the potential in most rough gemstones, but the surface can be dull or the rough forms misleading,” Anna says. 

Bario Neal’s rings with rough diamonds give a glimpse into the natural state of gemstones. Generally rough diamonds have been tumbled clean — think of the process like a high-pressure wash on a sidewalk or deck — to remove sediment or extraneous materials so you can see the stone better, but they’re otherwise unaltered. They’re not polished against a wheel to add facets or smooth the surface.

Find details about gemstone mining in Bario Neal’s reports on the ethical sourcing of sapphires and emeralds, colored gemstones, Australian diamonds, and Canadian diamonds.

Cutting and Polishing

Cutting and polishing gemstones reveals the crystal structures and colors of gemstones and sets their shape for setting in rings, earrings, bracelets, and necklaces. (“Bario Neal’s Guide to Fancy Diamond Cuts” has more about cuts and shapes.)

“Because we source gemstones from many small-scale, artisanal miners, we can request materials to be cut especially for us on site and delivered to us in a matter of months,” Anna says. She explains that other gemstones might be aboveground for years before they are cut and polished. “We could craft a custom designed ring with a Montana sapphire that was mined years ago and had been sitting with a U.S. specialty cutter who was waiting for the right project for that rough stone for some time.”

Cutting and polishing is a lesser-known phase of the jewelry industry and there are risks that workers may be exploited and unprotected amid unhealthy work practices. Bario Neal’s ethical sourcing standards aim to make sure all workers along their supply chain are treated fairly and operate in safe conditions.  

The New Yorker, in a feature about the diamond industry, talked to Oded Mansori, a manufacturer and distributor of rare diamonds, about the complexity of cutting gemstones: “Cutting a diamond, [Mansori] explained, is not merely a question of geometry. Certain types of stone can change color during the polishing process. Other stones contain faults, or ‘inclusions,’ that need to be worked around. Growth lines in the diamond — markers of different stages of crystal formation within a stone — must be considered; if you leave a line at the surface, it cannot be polished away. All decisions are irreversible: a cut diamond cannot be uncut. Mansori does not polish stones himself. He employs specialists for that task … The cutters, in Mansori’s opinion, are not artisans; they are artists.”   

Handcrafting Fine Jewelry

The Bario Neal team crafts fine jewelry with cut and polished gemstones at their Philadelphia workshop, and sometimes uses local partners in the manufacturing process. 

Anna notes that many people select gemstones for their Bario Neal jewelry based on healing properties or spiritual qualities. According to Healthline, for example, some turn to sapphires to heal eye issues or ease anxiety. “In custom design, if clients want to dig in with that side of it, there’s so much to work with in terms of these esoteric properties of gemstones,” Anna says. “We don’t necessarily tap into that for our design process for Bario Neal collections, but it has been part of a few personal projects for us. And for clients drawn to that energy, we can definitely incorporate it into custom designed jewelry.”

You might, of course, be attracted to a certain gemstone because of the color or the country of origin or your appreciation of the jaw-dropping power of what our planet can make. In an on-demand, rushed-delivery world, there’s something to love in having a piece of Earth that spans eras.

“Because of what jewelry inherently represents, gemstones are that much more powerful, like a talisman. We’re making pieces of decorative body armor,” Anna says. “So we work with clients to find out what they want that jewelry to represent, and gemstones are certainly a way to add layers of meaning.”