Which is the better diamond alternative?

A diamond alternative or simulant looks like a diamond, but is different in terms of chemical composition and every other way. Today, the most popular options are lab-created cubic zirconia and moissanite.

Tip: Ask the retail shop you're buying your rock from if they're selling cubic zirconia - some shops may attempt to conceal this fact by passing it off as a "trade secret diamond-like rock". Know your rights as a consumer!

History and origin

Moissanite is composed of silicon and carbon (SiC), while cubic zirconia contains a mix of zirconium and oxygen. The chemical composition and structure of moissanite is much closer to that of a diamond than cubic zirconia.

Durability

Moissanite’s hardness of 9.25 allows it to exhibit great resistance to scratches, making it a practical choice for daily wear compared to cubic zirconia's hardness of 8.0-8.5.

This makes moissanite an exceptionally hard stone and ideal for daily wear. It has high resistance to chipping and breaking. As cubic zirconia scratches easily, it can lose its surface lustre after just a few months with regular wear.

Did you know? 

• Using the Knoop hardness test as a point of reference, moissanite (3000kg/mm2) is more than twice harder than cubic zirconia (1370kg/mm2).
• Moissanite (7.6 PSI) is three times more resistant to chipping and breaking as compared to cubic zirconia (2.4 PSI).

High thermal conductivity

Cubic zirconia presents a unique set of challenges if you would like to make modifications to your jewellery. It shatters and turn into an opaque, milky colour when exposed to too much heat. Therefore, many jewellers refuse to perform repairs on cubic zirconia jewellery. 

Moissanite can easily withstand temperature variations during the jewellery manufacturing process and repairs at a jeweller’s bench. In fact, moissanite's thermal conductivity is comparable to a diamond. This is also why many diamond testers on the market incorrectly identify moissanites as diamonds.

Value

Compared to diamonds, both moissanite and cubic zirconia are more affordable options.

A high quality moissanite can retail for around $400 while a similar sized high-quality cubic zirconia will cost around $20. Cubic zirconia does not have any resale value. There exists merchants who conceal the fact that their stones are cubic zirconia and call it a "trade secret diamond simulant", and charging an extremely high mark up. Do ask questions and know that it is within your right to know what the stone is.

Moissanite is not a "fake diamond" and is a gemstone in its own right. It requires professional expertise and state-of-the-art technology to produce. Moissanite has retained its value over the past decade. 

Light performance

Moissanite has a Refractive Index (RI) of 2.65 whereas cubic zirconia's RI comes in at 2.15. Diamond has a RI of 2.42. Moissanite is extremely brilliant and demonstrates excellent light performance. This is one of the many reasons why it is favoured in engagement rings.

Cubic zirconia can sometimes appear glassy and lack the fire of diamonds and moissanites. Its sparkle may appear to be more superficial as a result.

Colour and clarity

Cubic zirconia is always flawless and have a colour grade of D. 

Moissanite, on the other hand, is rarely completely white or totally transparent. It can contain a slight yellowish tint and even some internal flaws due to a complicated production process. Like diamonds, they are never perfect.

The verdict

Although cubic zirconia is much more affordable, we choose moissanite due to its unrivalled brilliance, lifelong durability and value.

With a little basic TLC, moissanite will last you a lifetime and beyond.