Hello, jewelry enthusiasts! Here at Goldsmith Jewelers, we’ve served countless customers seeking high-quality, genuine gemstones for over a century. Today, we’re going to delve into one of the most mesmerizing gemstones out there: the opal. It’s important to know how to tell if an opal is real, and we’re here to provide you with all the knowledge you need.

Understanding Opals

Opal is a unique gemstone known for its play-of-color, created by microscopic spheres of silica. There are several types of opals, including common opal, precious opal, and fire opal. These gems form over millions of years in cavities within rocks, making each piece truly unique.

Common Types of Fake Opals

Unfortunately, like many precious stones, opals have their share of imitations. Here are the most common types:


  • Synthetic opals: Created in labs, these imitate the play-of-color found in natural opals.
  • Opal doublets and triplets: These are assembled from two or three layers, usually a thin layer of opal glued onto a darker material, or sandwiched between a dark back and a clear top.
  • Glass or plastic imitation opals: Simply colored glass or plastic designed to look like opal.

Methods to Determine Authenticity of Opals

Visual Inspection

  • Color play and pattern: Genuine opals are known for their unique play of color. Look for multiple vibrant colors that shift and change as the gemstone moves.
  • Body tone and transparency: Natural opals come in various tones from light to dark and can range from transparent to opaque.
  • Inclusions and imperfections: Natural opals may have tiny inclusions or imperfections. Too perfect a piece may hint at synthetics.

Physical Properties

  • Hardness: Opals are softer than many other gemstones. They rate between 5.5 to 6.5 on the Mohs hardness scale.
  • Density: Genuine opals are denser than glass or plastic.
  • Temperature: Real opals usually feel warmer than ambient temperature to the touch and take a while to heat up or cool down.

Advanced Methods

In some cases, you might need more advanced techniques to determine an opal’s authenticity:


  • Magnification: Inspect the opal under magnification to look for a consistent pattern and color play.
  • Spectroscopic analysis: Professionals may use this method to confirm the presence of water in the opal.
  • Refraction index: Real opals have a specific refractive index that professionals can measure.

When to Consult a Professional

While these home tests can provide guidance, they’re not foolproof. That’s when you might need the help of a professional. A trained gemologist can accurately assess an opal’s authenticity. At Goldsmith Jewelers, we offer expert appraisals conducted by our experienced team.

Tips for Buying Genuine Opals

  • Research the seller: Look into their reputation and reviews.
  • Ask the right questions: Ask about the origin, treatment, and if there’s any certification.
  • Look for certification: Certificates of authenticity from trusted labs can provide reassurance.


Knowing your opal’s authenticity is vital, whether you’re adding to your collection or giving a special gift. With these tips, we hope you’re equipped to make informed decisions. As always, Goldsmith Jewelers is here to help, ensuring that you have access to the finest quality gemstones.


For more insights into the wonderful world of gemstones, check out our blog or contact us to book an appointment with our experienced team.


Happy opal hunting!