How to Tell If an Opal Is Real — A UK Buyer’s Guide

How to Tell If an Opal Is Real — A UK Buyer’s Guide

Introduction

Opals are some of the most beautiful gemstones in the world, but they are also some of the most misunderstood. With synthetic opals, treated stones, triplets, glass imitations and mass-produced fakes flooding the global market, it’s more important than ever to know how to tell if an opal is real.

Whether you’re a jewellery maker, a collector, or someone buying their first opal, this guide will help you understand what genuine opals look like and how to avoid being misled.

This article also explains how Cornwall Gem ensures that every stone sold is a natural, authentic Australian opal.

Why Fake Opals Are So Common

Fake opals are common because:

• they are cheaper to produce

• inexperienced buyers can’t always tell the difference

• some sellers intentionally avoid mentioning treatments

• photo editing online hides flaws and gives false brightness

For many people, a “fake” opal is not obvious until it arrives in the post. That is why understanding the basics is essential.

The Three Main Types of Fake or Man-Made Opals

There are three common categories:

1. Synthetic Opal (Lab-Grown)

These stones are grown in a laboratory and mimic the appearance of natural opal, but their patterns are too perfect, too uniform and lack natural randomness.

Signs of synthetic opal:

• repeating patterns

• perfectly straight colour columns

• very “neat” colour blocks

• lack of natural matrix or unevenness

2. Imitation Opal (Glass or Resin)

These are not opals at all.

Signs:

• no depth

• plasticky look

• glitter-like colour

• colour only on the surface

3. Doublets and Triplets Sold as “Solid Opals”

Doublets and triplets are genuine opal layers, but they are not solid stones.

They are beautiful and affordable, but should always be labelled correctly.

A dishonest seller might simply call them “opal cabochons” without mentioning layers.

Simple At-Home Tests to Identify Real Opal

Here are reliable tests you can perform without damaging the stone.

1. Look for Natural Random Patterns

Real opals have chaotic, organic patterns. Fake opals often show:

• checkerboard patterns

• repeating geometric blocks

• straight vertical columns

Real opals are never symmetrical.

2. Check the Back of the Stone

Turn the opal over.

• Solid opals: natural uneven back, sometimes matte, sometimes polished

• Boulder opals: natural ironstone back

• Doublets: straight, sharp line between layers

• Triplets: glass or resin dome on top

If the back looks too perfect, machine-cut or jet black plastic, it is likely a doublet or synthetic stone.

3. Examine the Play-of-Colour

Natural opals show colour that appears to move within the stone as you tilt it.

Fake opals often show:

• colour that stays still

• colour that seems printed or painted on

• glitter-type sparkle

Natural play-of-colour is deeper and more three-dimensional.

4. Look for the Lizard Skin Effect (Synthetic Sign)

Many lab-grown opals show a “lizard skin” or “snakeskin” pattern.

This is a tell-tale sign of artificial production.

5. Check for Plastic or Resin Shine

Plastic or resin imitations often have:

• overly glossy surfaces

• light reflections that look waxy

Solid opal has a softer, more gemstone-like lustre.

6. The Weight Test

Resin and glass fakes are often lighter or heavier than expected.

Natural opals have a specific, consistent weight when compared to size.

7. Magnification Test

Use a jeweller’s loupe.

Under magnification, natural opals show:

• tiny irregularities

• depth

• internal structure

• subtle cracks or lines in boulder opal

Fake opals show:

• perfect uniformity

• repeated patterns

• plastic-like texture

Common Opal Scams UK Buyers Should Watch For

Sadly, these are common across marketplaces:

❌ Photo-enhanced brightness

Some sellers increase saturation or brightness digitally.

❌ “Australian opal” listed with no origin

If the seller doesn’t know the field or region, be cautious.

❌ Triplets sold as solids

If a stone is extremely bright and very cheap, it is likely layered.

❌ Incorrect stone names

Some sellers use terms like:

• rainbow opal

• fire opal (incorrectly used)

• synthetic boulder opal

• Ethiopian “Australian-style” opal

These are red flags when misused.

How UK Opal Direct Guarantees Authenticity

Cornwall Gem specialises in genuine natural Australian opals only. Here’s how authenticity is ensured:

✔ Direct sourcing from trusted Australian miners

Every stone comes from reputable suppliers and mining contacts in:

• Lightning Ridge

• Coober Pedy

• Queensland

• Yowah

• Koroit

No unknown sources. No synthetic stock.

✔ Honest, natural lighting photography

Photos are taken:

• in daylight

• without filters

• without saturation boosts

• without artificial enhancements

This means customers see the true colour, pattern and brightness.

✔ Clear labelling

Each listing clearly states:

• type of opal

• origin

• weight

• dimensions

• whether it is boulder, crystal, white or rough

• whether the stone is polished

No hidden information, no misleading names.

✔ A strong reputation and repeat buyers

Cornwall Gem has earned trust because:

• customers receive what they expect

• stones look the same in person as they do online

• UK buyers appreciate fast delivery and no import fees

Authenticity is the foundation of the brand.

When to Get a Professional Opinion

Most buyers don’t need a formal gemmology certificate, but you may consider one if:

• the stone is high-value

• you want to set it in fine jewellery

• you’re unsure about authenticity

• the origin is important to you

A certified gemmologist or jeweller can easily confirm natural opal under magnification.

Final Thoughts: Buy With Confidence

Knowing how to tell if an opal is real will help you avoid disappointment, overpriced synthetics and misleading listings. With the right knowledge and a trusted seller, you can buy opals confidently and safely.

This is why so many buyers choose Cornwall Gem a transparent, ethical and trusted source of natural Australian opals delivered right here in the United Kingdom.

Your opal should be genuine, beautiful and exactly what you expect. When you buy from Cornwall Gem, that’s a guarantee.