Gemstones: Natural, Synthetic, or Imitation?

All That Sparkles Is Not A Gem

Here’s a whirlwind overview to help you understand the differences between natural gems, synthetics, and imitations.

What Is A Gemstone?

You will find varying definitions and opinions on what, technically, constitutes a gemstone. In my gemological training we were taught that a gemstone is a naturally occurring mineral which is considered to have beauty, rarity, and durability. In addition to inorganic gemstones, such as diamonds, topaz, peridot, garnets, etc., there are organic materials which are considered gems, such as pearls and amber.

How Can You Tell One Gemstone From Another?

In the majority of cases it is impossible to accurately identify a gemstone just by looking at it.  A red stone could be garnet, ruby, spinel, or something else. A blue stone could be sapphire, topaz, tanzanite, or something else. Scientific testing, using equipment such as a polariscope, refractometer, and microscope, is used to identify gemstones and to separate natural gems from lab-grown synthetics and imitations.

A gem has a definite chemical composition. Gems are organized into species based on their chemical, physical, and optical properties, and within the species there may be variations.

The quartz gem species, for example, includes many different varieties. Amethyst is the purple variety of quartz, and citrine is a golden variety of quartz. In the beryl gem species, the green variety is emerald, and the seawater blue-green variety is aquamarine.

Diamonds are the only gemstone composed of a single element: carbon.

Certain gemstones, such as opal and labradorite, have visual characteristics which make them easy to identify by sight, but they are the exception.

Why Should I Care What The Gem Is As Long As It’s Pretty?

I think that knowing what you are purchasing is important. And knowing that the person selling it to you is honest about what they are selling is even more important. For one thing, there are enormous variations in the value of natural gemstones, and also in the value of a natural gem versus its lab-grown equivalent.

Here’s an example. I compared wholesale prices at a reputable jewelry supplier. A 6mm round natural blue sapphire would cost $695. A lab-grown blue sapphire would cost $6. So the natural stone is over than 100 times more valuable than the lab-grown one.

In addition to the question of price, certain gems have certain meaning to people. If you want to buy a pair of ruby earrings for your wife because her birthday is in July (ruby is the July birthstone), then you want to be sure you are getting a ruby, not a garnet.

180720_synthetic corundum crystals
Lab-Grown Crystals of Ruby & Sapphire (corundum gem species). Photo: GIA

What Is A Lab-Grown Gemstone?

A lab-grown gemstone is a man-made product which can be either a synthetic version of a natural gemstone or an imitation of a natural gemstone. A synthetic must have the same chemical, physical, and optical properties as the natural gem. For example, a natural diamond is composed of carbon, therefore a synthetic diamond must also be composed of carbon.

An imitation, on the other hand, merely looks like a gemstone. Cubic Zirconia, commonly known as CZ, is an imitation. Originally introduced into the jewelry market to imitate diamonds, CZs are now manufactured in all colors, shapes and sizes in order to simulate a wide range of natural gems.

I’ve created this chart, which you can download as a PDF, as a visual guide to help understand this.


Are Lab-Grown Gems Eco-Friendly?

Some manufacturers and sellers of lab-grown gemstone synthetics and imitations claim they are more “eco friendly”. For this article, I did a little research to see if these claims were supported, and learned (not surprisingly), that the answer is not clear-cut and that no objective scientific studies have been done. To come up with an answer one must first define what it means to be eco-friendly and studies must look at the impact of the entire supply chain.

Even Tom Chatham, whose company manufactures high-quality synthetic emeralds and rubies, has been quoted on the subject as saying  “I can’t say anything personally, because every chemical we use comes out of the ground”.

Frauds I Have Encountered

There is nothing wrong with selling synthetic gemstones or gem imitations, as long as the seller is clear about the true nature of their product. However, Federal Trade Commission regulations state that such items must be clearly labeled, and that failure to do so is an “unfair and deceptive” practice. As such, it can be prosecuted as consumer fraud (extracts from the FTC are included at the end of this article).

Customers do sometimes bring me a stone or a piece of jewelry they have purchased elsewhere and ask me to identify the gem, and sometimes I see an advertised claim which is clearly false.  Here are just a few examples of consumer fraud which I have, sadly, encountered:

  • Cubic Zirconia (CZs) being sold as “champagne topaz from Brazil” (this was the description written on the customer’s receipt, and the customer subsequently had a certified gemologist test the stones — they were just fakes). This same business also sold CZs and falsely described them on various occasions as “cultured white sapphire” or amethyst or aquamarine.
  • A business selling CZs and misleadingly identifying them as “tanzanite zirconia” (which is not a tanzanite, it is not a lab-grown tanzanite, it is merely a CZ colored to imitate a tanzanite), or “genuine lab-grown sapphire CZ” (again, not a sapphire, not a lab-grown sapphire, merely a blue cubic zirconia).
  • A bi-color quartz crystal which was sold as tourmaline (tourmaline would have been much more valuable).
  • Citrine being sold as topaz (both are golden-colored gems). I once saw a ring with a yellow gemstone advertised as a “citrine topaz”. Citrine and topaz are two different gem species, and the golden variety of topaz is dramatically more expensive than citrine. The question in this instance was whether or not the word “citrine” was being used as description of the color of a gem which was really a topaz (i.e. golden topaz), or if the word “topaz” was being used to give an inflated sense of value to a gem which was really a citrine. It was, in fact, a citrine, so the inclusion of the word “topaz” was a false and misleading description.

Could It Be An Honest Mistake?

Errors are alway possible. A reputable business will stand behind what they sell and correct their mistakes. If the identification of a gem is unknown, it should be labeled as such and priced accordingly.

Tips For Consumers

  • Ask questions. Ask if the stone is natural or lab-grown. If the answer is lab-grown, ask if it is a synthetic or an imitation. Be suspicious if you cannot get a clear and simple answer to your questions.
  • Be wary of instances where a gem name, such as sapphire or tanzanite, is being used to describe the COLOR of the stone, not the actual stone.
  • Always get a complete description written on the receipt, including the purity of the metal and the identification of the gemstones. If the gems are man-made, the receipt should say “lab-grown,” “man-made” or something equally clear and obvious. If the gem is an imitation rather than a synthetic, the receipt should say “imitation” or “simulated” or something equally clear and obvious.
  • If you are purchasing a very high-end gemstone and have any concerns about its authenticity, you might consider sending it to a reputable lab, such as the GIA (Gemological Institute of America) for independent analysis.
  • Be wary of the big price drop: “normally these earrings would be $200, but today only they are half off”.

Select Federal Trade Commission Regulations

23.23   Misuse of the words “ruby,” “sapphire,” “emerald,” “topaz,” “stone,” “birthstone,” “gemstone,” etc. (link to FTC site).

(a) It is unfair or deceptive to use the unqualified words “ruby,” “sapphire,” “emerald,” “topaz,” or the name of any other precious or semi-precious stone to describe any product that is not in fact a natural stone of the type described.

(b) It is unfair or deceptive to use the word “ruby,” “sapphire,” “emerald,” “topaz,” or the name of any other precious or semi-precious stone, or the word “stone,” “birthstone,” “gemstone,” or similar term to describe a laboratory-grown, laboratory-created, [manufacturer name]-created, synthetic, imitation, or simulated stone, unless such word or name is immediately preceded with equal conspicuousness by the word “laboratory-grown,” “laboratory-created,” “[manufacturer name]-created,” “synthetic,” or by the word “imitation” or “simulated,” so as to disclose clearly the nature of the product and the fact it is not a natural gemstone.

(c) It is unfair or deceptive to use the word “laboratory-grown,” “laboratory-created,” “[manufacturer name]-created,” or “synthetic” with the name of any natural stone to describe any industry product unless such industry product has essentially the same optical, physical, and chemical properties as the stone named.

23.24   Misuse of the words “real,” “genuine,” “natural,” “precious,” etc. (link to FTC site)

It is unfair or deceptive to use the word “real,” “genuine,” “natural,” “precious,” “semi-precious,” or similar terms to describe any industry product that is manufactured or produced artificially.

About Me & My Work

I am Lorraine Hornby, and I am a jeweler and a Certified Gemologist, SCC. I design and create unique, contemporary jewelry. In general, I use only natural gems and cultured pearls in my work, although I do use synthetic gems if the customer requests this for budgetary reasons. My work can be seen and purchased at