How Gemstones Originated and the Different Types of Gemstones
Gemstones are nature’s exquisite art, forged deep within Earth over millions even billions of years. They form when specific minerals crystallize under unique conditions of heat, pressure, or fluid chemistry. Each process yields stones with distinct colors, hardness, and optical properties. From the fiery birth of diamonds in the mantle to the gentle deposition of opals in sedimentary basins, gemstones tell the planet’s geological story. Precious varieties like diamond, ruby, sapphire, and emerald sit alongside a rich cast of semi-precious stones such as amethyst, topaz, and peridot.
Geological Formation of Gemstones
Gemstones originate through three principal geological mechanisms: igneous, metamorphic, and hydrothermal or sedimentary processes. Igneous formation occurs when magma cools and crystallizes, isolating gem-forming minerals in dyke veins or pegmatites. Metamorphic stones arise when existing rocks undergo intense pressure and temperature shifts, triggering recrystallization. Hydrothermal gems develop from hot, mineral-rich fluids that migrate through fractures, depositing crystals as the solution cools. Finally, some gemstones form in sedimentary environments where minerals precipitate from groundwater or accumulate from weathered rocks.
Classification of Gemstones
Gemstones can be classified by chemical composition, crystal structure, and value category.
• Chemical groups include silicates (e.g., olivine), oxides (e.g., spinel), carbonates (e.g., malachite), and native elements (e.g., diamond).
• Crystal systems cubic, hexagonal, tetragonal, etc. govern the internal lattice that produces phenomena like asterism or chatoyancy.
• In the trade, “precious” traditionally refers to diamond, ruby, sapphire, and emerald, while all other gem minerals are termed “semi-precious.”
Precious Gemstones
These are traditionally the most valued for rarity and brilliance.
• Diamond – Pure carbon, unmatched hardness, often colorless or fancy hues.
• Ruby – Red variety of corundum, colored by chromium.
• Sapphire – All other colors of corundum (blue, pink, yellow, green).
• Emerald – Green beryl, colored by chromium or vanadium.
Semi-Precious Gemstones
Still stunning, but more abundant or varied in quality.
• Amethyst – Purple quartz, popular and affordable.
• Citrine – Yellow to orange quartz.
• Topaz – Found in blue, pink, yellow, and clear varieties.
• Peridot – Lime green olivine, often found in volcanic rock.
• Garnet – Deep red, but also green, orange, and purple varieties.
• Tourmaline – Comes in nearly every color, including bi-color.
• Aquamarine – Pale blue beryl, cousin to emerald.
• Zircon – Often confused with diamond, available in many colors.
• Spinel – Red, pink, and violet hues, often mistaken for ruby.
Organic & Exotic Gemstones
Formed from biological processes or unique geological conditions.
• Opal – Iridescent play-of-color, formed from silica spheres.
• Pearl – Produced by mollusks, natural or cultured.
• Amber – Fossilized tree resin, golden to brown hues.
• Coral – Marine skeleton, often red or pink.
Rare & Collector’s Gemstones
Ideal for storytelling and high-end custom pieces.
• Tanzanite – Blue-violet zoisite, found only in Tanzania.
• Alexandrite – Color-changing chrysoberyl (green to red).
• Moonstone – Exhibits adularescence, a soft glow.
• Labradorite – Displays labradorescence, a vivid flash of color.
• Chrysoprase – Apple-green chalcedony.
• Kyanite – Blue with unique hardness variation.
Conclusion
Gemstones capture both geological marvel and human imagination. Their birth in Earth’s crucible, coupled with millennia of cutting and polishing, transforms raw mineral into a jewel. Whether you’re drawn to the fire of diamond or the mystery of opal, each stone carries a narrative of planetary forces. At Custom Jewellery Designs in Hillarys, Perth, we celebrate this legacy by handcrafting settings that honor every gem’s origin and brilliance.
