There is a great deal of confusion on the topic of diamonds, diamond simulants, that which is sometimes called a "created diamond" and outright fakes. This guide is to give a basic understanding of some of the differences between these things, and what to look for (and ask about) when you're considering buying jewellery with any kind of simulated diamonds.

First, a brief look at the terminology. A "simulant" is something that "simulates" or "looks like" something else. A diamond simulant can be nearly anything that looks reasonably like a diamond. Some simulants are very good and very beautiful, some are completely unconvincing, some are in between, and for many, it's simply a matter of taste.

In the jewellery world, you also have that which is known as a "created" gemstone. In order to legally be called a created gemstone, the synthetic (i.e., manufactured or created) stone must be chemically, physically, and visually identical to the natural version. Simulated diamonds do not fulfill this requirement. They may look quite like diamonds, but unless they are chemically, physically, and visually identical, they are not "created diamonds".

There are a number of jewels that can be rightfully considered diamond simulants, including some kinds of garnet, some colours of zircon (note: cubic zirconia is not the same as a zircon!), sphene, rutile, white topaz, white sapphire, and synthetic spinel. This article will go into detail only on the two most popular diamond simulants (cubic zirconia and moissanite), and consider that which is known as as "cultured diamond" or "synthetic diamond".

Cubic Zirconia

Cubic Zirconia (or cubic zirconium; zirconia would actually be the plural) is an extremely popular and versatile lab-created gemstone. (Technically, there is such a thing as naturally occurring cubic zirconia in mineral form, but the mineral - zirconium oxide (ZrO2) - is extremely rare, it is not normally gemstone quality, and it can be safely stated that all commercial cubic zirconia are, indeed, lab created. Don't fall for it if someone offers to sell you a "natural cubic zirconia" ring!)

Cubic Zirconia is commonly abbreviated CZ, to the point that professional jewellers refer to the stones by those initials. Note that there is also a gemstone named "zircon" but it is not the same as a cubic zirconia.

To the untrained eye, CZ looks just like a good quality diamond, although the CZ does have slightly less brilliance than a diamond and more fire (flashes of color), and while it is almost as hard as a diamond, it is not as dense (a one carat CZ is larger than a one carat diamond as a result). Trained gemologists can usually tell the difference between a diamond and a CZ, but even they may require a special tool (a thermal conductivity test) to do so with absolute certainty. Put in a good quality setting, it is extremely difficult for anyone to tell that a quality Cubic Zirconium is not a diamond. While quality does vary, CZ are not cheap "paste" jewels or rhinestones or glass. Good quality CZ stones are brilliant and beautiful, and they are extremely popular for this very reason. They are sold in reputable jewellery stores around the world.

CZ are not limited to their usual diamond-like appearance. CZ can be coloured in various ways to resemble many coloured including sapphire, ruby, citrine, amethyst, topaz (all colours), emerald, peridot, and colored diamonds, including champagne, canary, and the very popular pink. (How convincing the stones are as the jewels is debatable, but coloured CZ can still be extremely pretty.)

CZ are sometimes referred to as "created diamonds", but this is incorrect, as they are not identical to diamonds visually, chemically, or physically.

Moissanite

Another diamond simulant that's getting a fair bit of attention lately is the jewel known as moissanite. The word moissanite is a trade name given to silicon carbide (SiC) which is synthesised for use in the jewellery business. Silicon carbide is also known generally as "carborundum" and has other industrial uses.

Gem-quality silicon carbide was introduced in 1998 as a lower-cost alternative to diamond. Moissonite has a higher index of refraction and greater light dispersion; this greater dispersion and index of refraction gives it more fire and brilliance than diamond. It is also quite hard although not as dense as diamond, and it has a similar thermal conductivity as diamond (so the thermal testing that will determine that a CZ is not a diamond doesn't work on moissanite). Moissanite has a slight green tint to it which can intensify in bright natural light. Also, moissanite's, high refraction and dispersion is thought by some to be distracting and harsh, but many people do find these sparkling stones to be quite beautiful, and moissanite continues to grow in popularity.

Moissanite is generally more expensive than cubic zirconia, but certainly far less expensive than natural diamonds.

Cultured Diamonds

There is such a thing as a laboratory-created diamond, although they do not fulfill the requirement to be legally called "created" diamonds, as they are visually identical to natural diamonds, but with slight physical and chemical differences. These synthetic diamonds are also known as industrial diamonds, manufactured diamonds, or cultured diamonds (a name similar to "cultured pearls" because of the laboratory process used).

Synthetic diamonds are visually identical to natural diamonds, as mentioned, but their differences may be distinguished from natural diamonds by spectroscopy in infrared, ultraviolet, or X-ray wavelengths. Only three companies in the world produce gem-quality synthetic diamonds. All three of these manufacturers laser-inscribe serial numbers on their gemstones, and these serial numbers can and will identify the stones as synthetics.

Although not as expensive as natural diamonds, synthetic gem-quality diamonds are still quite expensive, especially compared to the price of diamond simulants such as moissanite and cubic zirconia.

How can I tell the difference?

Given the way sellers (and many wholesale suppliers!) sometimes misuse terms, it can be confusing to navigate the jewellery categories. Some sellers use incorrect terms because they don't know any better, but some do it deliberately to mislead buyers. The best thing you can do is be informed prior to bidding.

First, always check the seller's feedback! What have others said about the goods they received from the seller? It's true that there are always cases where people are just not satisfied no matter what kind of service they get or the goods they receive, but if a seller consistantly has regular negative feedback, especially if the comments are that the quality of the item received was poor or that the item was fake, this is a pretty good warning sign! Certainly take negative feedback in the context in which it's given and balance it against the rest, but if a seller has buyer after buyer saying that the item they received was cheap or low quality or fake, that should raise a red flag to potential buyers.

After you're satisfied with the seller's feedback history, the best thing that a buyer can do is ask the seller questions. Ask them what, specifically, they mean by "created diamonds " or "natural cubic zirconia" or whatever term they're using. Ask before you bid, and then carefully consider the answer you get, and the degree of knowledge the seller shows on the subject. Not all sellers are (nor should they have to be) certified gemmologists, but they should have a good working knowledge of what they're selling and be able to answer your questions clearly and professionally..

There's nothing inherently wrong with diamond simulants, so long as you know what you're buying. In fact, diamond simulants can be extremely beautiful (there is a reason, after all, that CZ is so very popular and moissanite is growing in popularity all the time!). Just exercise a bit of caution, check feedback, and ask the right questions prior to bidding, and you can get a lovely piece of jewellery with sparkling jewels that you'll be pleased to wear. We hope that this guide has given you some insights that will be helpful in navigating the sometimes confusing jewellery market on eBay.