Buying Gemstones: How to Distinguish Real from Synthetic Stones

When buying gemstones, there are confusions, misunderstandings, and sometimes even deliberate deceptions. Is the ruby in a department store ring really genuine? What does "synthetic" mean? And is a lab-grown gemstone less valuable than a natural one? This comprehensive guide answers all important questions – so you can make informed and confident decisions on your next gemstone purchase.

The Most Important Categories: Natural, Synthetic, Imitation

The first misunderstanding: Not all non-natural stones are the same. There are three fundamentally different categories:

Natural Gemstones

Formed in the earth over millions of years through geological processes. They are unique and have natural inclusions (the so-called "fingerprint" of the stone). Natural gemstones are generally more expensive than their synthetic counterparts – due to their rarity and the symbolic value of being "grown from the earth."

Synthetic / Lab-Grown Gemstones

Chemically, physically, and optically identical to natural stones – only grown in a laboratory under controlled conditions. A lab-grown sapphire is a real sapphire (corundum), just not formed in the earth. Lab-grown stones are more affordable (40–80%), sustainable, and almost indistinguishable from natural ones for the untrained eye. They are not fakes!

Imitations (Simulants)

Materials that only resemble gemstones but are chemically completely different. Cubic zirconia (CZ) imitates diamond, but it is not a diamond. Blue glass imitates sapphire, but it is glass. Imitations do not have gemstone properties and are significantly cheaper.

Common Gemstone Confusions and Deceptions

Zirconia Sold as Diamond

The most common problem in the inexpensive jewelry segment. Zirconia looks deceptively similar to diamond but is significantly softer (Mohs 8–8.5 instead of 10) and becomes duller over time. Identification test: Diamond tester or loupe (zirconia shows no inclusions; perfect stones are often synthetic).

Synthetic Ruby/Sapphire Without Declaration

Lab-grown rubies and lab-grown sapphires look identical to natural ones. Reputable dealers explicitly declare this. If "natural" or "lab-grown" is missing, always ask.

Sodalite Instead of Lapis Lazuli

Sodalite looks very similar to lapis lazuli – both deep blue stones. Genuine lapis lazuli is recognizable by golden pyrite inclusions and characteristic veining. Sodalite lacks the pyrite specks.

Dyed Howlite Instead of Turquoise

White howlite can be treated with blue-green dye to deceptively resemble turquoise. Genuine turquoise has a characteristic veining (matrix); dyed howlite often appears too uniformly blue.

Dyed Chalcedony Instead of Onyx

Black onyx is often dyed chalcedony – this is an accepted trade standard and not a deception. Important: The dealer should communicate transparently if the stone has been dyed.

How Do You Recognize Genuine Gemstones at Home?

The Temperature Test

A genuine gemstone feels cold and warms up slowly (because crystals are poor heat conductors). Glass and plastic quickly adopt body heat. Not a 100% test, but a first indication.

The Tooth Test (for Pearls)

Genuine pearls feel slightly gritty against the teeth; imitation pearls feel smooth like glass.

The Loupe (10x)

Natural gemstones almost always have inclusions – this is a quality characteristic of authenticity. Perfect, inclusion-free stones from inexpensive jewelry are often synthetic or imitations.

UV Light

Many gemstones fluoresce characteristically under UV light: Genuine blue sapphire often does not; ruby intensely red; diamond usually blue. Deviating fluorescence can indicate treatments.

What Are Certificates and When Are They Important?

For valuable gemstones (diamond, ruby, sapphire, emerald from approx. €500 stone value), certificates are important:

• GIA (Gemological Institute of America): Most internationally recognized certification body. Documents 4 Cs, origin, and treatments.
• AGL (American Gemological Laboratories): Particularly known for colored gemstones.
• Gübelin Gem Lab (Switzerland): Highest standard for rare gemstones like Burmese ruby or Kashmir sapphire.

For less expensive gemstones under €200, a certificate is not strictly necessary if the dealer communicates materials transparently.

What to Look for When Buying Online

• Clear indication: "Natural" or "Lab-grown" or "Synthetic"
• Origin statement for higher quality stones
• Detailed product photos from different perspectives
• Certificate or quality specifications (color, clarity, cut)
• Return policy – reputable dealers offer at least 14 days

Treatments: What Is Acceptable?

Almost all gemstones are treated – this is largely accepted in the industry but should be communicated:

• Heating (heat treatment): Standard for sapphires, rubies, aquamarine – improves color and clarity. Must be stated.
• Oiling (emerald): Oiling inclusions is standard. "Minor oil" is acceptable; "significant" diminishes value.
• Resin impregnation (Jade Type B, turquoise): Stabilizes the stone – mandatory to communicate.
• Irradiation: Alters color; controversial for some stones.

Quality Jewelry with Genuine Stones at Corelune Jewellery

Transparency in material specifications is important to us at Corelune Jewellery. We openly communicate what goes into our jewelry pieces. Discover our gemstone collection and buy with confidence.

👉 Discover gemstone jewelry now – transparent, high-quality, honest!