How to Tell If a Stone Is Real or Synthetic

May 26, 2026

The question of whether a stone is real or synthetic is one of the most common questions in jewellery and one that requires clarification before it can be answered usefully. Real versus synthetic is not the same as genuine versus fake. A synthetic stone can be entirely genuine a real material with real properties, just created in a laboratory rather than formed in the earth.

The more useful question is: what is this stone, and does it perform as described? This guide covers practical tests and visual indicators that help answer that question.

Key Takeaways:

1. Real versus synthetic is not genuine versus fake synthetic stones are real materials

2. The relevant distinction is natural (formed in earth) versus synthetic (created in laboratory)

3. Glass and plastic imitations are the actual fakes these are not stones at all

4. Simple tests can distinguish stones from glass/plastic but cannot distinguish natural from synthetic without equipment

5. Temperature test is the most accessible: real stones feel cold to the touch glass warms quickly

The Stone Hierarchy — What You Might Have

STONE TYPES — FROM NATURAL TO IMITATION

Type	What It Is	Is It a Real Stone?	How to Identify
Natural gemstone	Formed in earth over geological time	Yes — entirely real	Requires gemological testing to confirm natural origin
Lab-created gemstone	Chemically identical to natural grown in laboratory	Yes — real stone, lab origin	Indistinguishable from natural without specialist equipment
Cubic Zirconia	Zirconium oxide synthesised crystal	Yes — real synthetic material — not glass	Heavier than glass, colder than glass, more brilliant than glass
Moissanite	Silicon carbide synthesised crystal	Yes — real synthetic material	Double refraction visible under magnification
Crystal (glass)	Precision-cut lead-free glass	No — glass, not a stone	Warms quickly in hand, lighter than CZ, less sharp brilliance
Plastic imitation	Coloured plastic	No — plastic	Warms immediately, scratches easily with fingernail, very light

Practical Tests Anyone Can Do

1. The temperature test

Real stones including CZ are thermal conductors that feel cold to the touch and take time to warm in the hand. Glass warms more quickly. Plastic warms almost immediately. Hold the stone or piece in your closed palm for 30 seconds. A real stone will feel distinctly cooler than glass or plastic of the same size.

2. The weight test

Stones are generally heavier than glass of the same size. CZ is notably heavy — heavier even than diamond of the same size. If a stone feels surprisingly light for its visual size, it may be glass or plastic. This test requires comparison — knowing what the expected weight should be.

3. The scratch test — carefully

Real stones with hardness 7+ Mohs will not be scratched by a steel nail (hardness ~6.5). Glass and plastic will show scratches. CZ (8–8.5 Mohs) will not be scratched by steel. This test should only be done on an inconspicuous area of the stone and only when necessary scratching can damage lower-quality surfaces.

4. The fog test

Breathe on the stone. Real stones including CZ disperse fog almost instantly due to thermal conductivity. Glass holds fog slightly longer. This is a rough indicator, not a definitive test.

The Bottom Line

Distinguishing a stone from glass or plastic is practical with simple tests. Distinguishing natural from lab-created requires specialist equipment. For the purposes of choosing jewellery, the most useful distinction is between genuine stone materials (natural, lab-created, CZ, moissanite) and glass or plastic imitations. The first category produces durable, beautiful jewellery. The second does not. Whether the stone within the genuine category is natural or synthetic is a question of origin preference and price point not of quality.

Frequently Asked Questions

How can I tell if a stone in my jewellery is real?

Start with the temperature test: hold the piece in your closed hand for 30 seconds. Real stones including CZ feel distinctly cooler than glass or plastic. Then assess weight: real stones are generally heavier than glass of the same visual size. Finally, look at the brilliance: real stones with precision facets produce sharp, clear light reflections. Glass produces more diffuse light. These tests distinguish real stone material from glass or plastic but cannot determine whether a real stone is natural or lab-created.

What is the difference between a real stone and a synthetic stone?

A real stone is any material with genuine crystalline structure and physical properties including synthetic stones like CZ and moissanite. A synthetic stone is a real stone material created in a laboratory rather than formed in geological conditions. Glass and plastic are not stones they lack crystalline structure and the physical properties of genuine stone materials. The real versus synthetic distinction commonly used in jewellery actually means natural versus lab-created both are real materials.

Is cubic zirconia a real stone or fake?

Cubic zirconia is a real synthesised crystalline material not glass, not plastic, not a fake. It is zirconium oxide in cubic crystal form, created in a laboratory. It has real hardness (8–8.5 Mohs), real optical properties, and real beauty. It is not a natural stone it does not form in the earth. It is also not a fake it is a genuine synthetic stone material. The word fake suggests misrepresentation. CZ sold as CZ is exactly what it is: a real synthesised stone.