Gemstone 101: Everything You Need to Know About Gemstones

Did you know that the largest diamond ever discovered was 3,106 carats? Gemstones, with their dazzling array of colours and storied histories, have captivated us for centuries.

What Are Gemstones?

Gemstones are naturally occurring minerals or organic materials that are cut and polished for use in jewellery and other decorative items.

Most gemstones form deep within the Earth's crust under conditions of extreme heat and pressure, a process that can take millions of years. Some gemstones, like diamonds, form in the Earth's mantle and are brought to the surface through volcanic eruptions. Others, such as opals, form in sedimentary rocks through the gradual accumulation of silica-rich water. This intricate process gives each gemstone its unique characteristics and beauty. 

Gemstones are broadly categorised into three groups:

  • Precious stones: This category includes diamonds, rubies, sapphires, and emeralds. These stones are known for their rarity, durability, and exceptional quality. They are often considered the most valuable.
  • Semi-precious stones: This group encompasses a wide variety of stones, such as amethyst, garnet, peridot, and citrine. While more abundant than precious stones, they can be equally stunning and are highly valued for their beauty and uniqueness.
  • Organic stones: Unlike mineral-based gemstones, organic stones like pearls, amber, and coral originate from living organisms. Pearls are formed within mollusks, amber is fossilised tree resin, and coral is created by marine organisms. These gemstones offer a unique, natural charm.


The 4 Cs of Gemstones

When it comes to evaluating gemstones, the 4 Cs are key: Cut, Colour, Clarity, and Carat Weight.

  • Cut: The cut of a gemstone refers to how it has been shaped and faceted, enhancing its brilliance and value by maximising light reflection.
  • Colour: Colour is one of the most important factors in determining a gemstone's value, with hue, tone, and saturation all playing a role in the stone's overall appeal.
  • Clarity: Clarity measures the presence of internal or external flaws, known as inclusions and blemishes. Fewer inclusions typically mean a higher quality gemstone.
  • Carat Weight: Carat weight measures the size of the gemstone. Larger stones are rarer and often more valuable, but the other three Cs also significantly impact value.

Popular Gemstone Cuts & Shapes

Gemstones come in a variety of cuts and shapes. Here are some of the most popular ones over the years:

  • Round: Classic and timeless, the round cut maximises brilliance with its 58 facets.
  • Princess: A modern favourite, the princess cut is square-shaped with sharp corners, offering excellent sparkle.
  • Emerald: Known for its rectangular shape and step cuts, the emerald cut highlights the stone's clarity.
  • Oval: An elongated version of the round cut, the oval cut combines brilliance with a unique shape.
  • Marquise: With its elongated shape and pointed ends, the marquise cut makes a dramatic statement.

Current popular cuts include:

  • Cushion: Combining a square shape with rounded corners, the cushion cut is both vintage and contemporary.
  • Pear: Resembling a teardrop, the pear cut is elegant and flattering on rings and pendants.
  • Radiant: A combination of the emerald and round cuts, the radiant cut offers brilliance and unique facets.
  • Asscher: Similar to the emerald cut but square, the Asscher cut has a distinct art deco appeal.
  • Heart: A romantic choice, the heart cut is a symbol of love and affection. 

Top Gemstone Treatments & Enhancements

To enhance their appearance, gemstones often undergo treatments. Here are the top five methods:

  • Heat Treatment: This method involves heating gemstones to high temperatures to enhance their colour and clarity. It is commonly used for sapphires and rubies, making them more vibrant and reducing visible inclusions.
  • Irradiation: This treatment uses radiation to change or improve the color of gemstones. It is often used for topaz and diamonds, giving them a more desirable hue.
  • Oiling: Primarily used for emeralds, this process fills fractures with oil to reduce their visibility and improve clarity. The oil has a similar refractive index to the gemstone, making imperfections less noticeable.
  • Fracture Filling: This technique involves filling surface-reaching fractures in gemstones with a glass-like substance. It is commonly used for diamonds to enhance clarity and make the fractures less visible.
  • Dyeing: Adds colour to gemstones like agate and turquoise to enhance their appearance. The dye penetrates the gemstone's surface, giving it a more uniform and appealing colour.

Caring for Your Gemstones

Proper care ensures your gemstones remain stunning for years to come.

Cleaning Tips: Different gemstones require different cleaning methods. Generally, warm soapy water and a soft brush are safe for most stones. Avoid harsh chemicals and ultrasonic cleaners unless specified.

Storage: Store gemstones individually in soft cloth pouches or lined jewellery boxes to prevent scratches and other damage.

Maintenance: Regularly check your gemstones for signs of wear and tear. For professional cleaning and maintenance, especially for valuable pieces, consult a jeweller.


Understanding gemstones can deepen your appreciation for these natural wonders and help you make informed choices when purchasing jewellery. Whether you're drawn to the timeless beauty of a diamond, the vibrant hues of a semi-precious stone, or the unique charm of organic gems like pearls and amber, there's a gemstone out there that’s perfect for you. Happy gem hunting! 

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