Best Diamond Simulants: Comparing Strontium Titanate, Cubic Zirconia, and Moissanite

In the world of gemology, a diamond simulant is any material that mimics the appearance of a diamond but does not share its chemical composition or crystal structure. Unlike lab-grown diamonds, which are chemically identical to natural diamonds, simulants are entirely different substances. For the enthusiast or professional, understanding the nuances between strontium titanate, cubic zirconia, and moissanite is essential for accurate identification and valuation.

Comparison Table

Shared Features

While chemically distinct, these three materials share a primary goal: the visual replication of a colorless, brilliant-cut diamond. All three are typically produced in laboratory settings to ensure a level of purity and clarity that exceeds most natural gemstones. They are all isotropic or nearly so in their interaction with light, allowing them to be faceted in the same traditional brilliant cuts used for diamonds to maximize light return.

Important Differences

The primary distinctions lie in their optical performance and physical resilience.

Optical Performance (Fire and Brilliance)

Moissanite is renowned for its extreme “fire.” Because its dispersion is significantly higher than a diamond’s, it produces a “rainbow effect” that can appear overly vivid compared to a natural stone. Cubic Zirconia has a dispersion closer to diamond but lacks the same brilliance, often appearing “flat” in low light. Strontium Titanate possesses a very high refractive index, providing excellent brilliance, though it is rarely used today due to its softness.

Physical Durability

There is a vast disparity in hardness. Moissanite is nearly as hard as diamond, making it suitable for daily wear in engagement rings. Cubic Zirconia is respectable but will develop surface scratches over time. Strontium Titanate is the outlier; with a Mohs hardness of only 5.5, it is prone to scratching and chipping, rendering it unsuitable for high-wear jewelry.

Gemologist’s Note: When distinguishing Moissanite from Diamond, a thermal conductivity probe is the most efficient tool. Moissanite conducts heat almost as well as diamond, whereas CZ and Strontium Titanate act as insulators.

Suitability by Use

• Moissanite: Best for those seeking a permanent, durable, and ethical alternative to diamonds for engagement rings or heirloom jewelry.
• Cubic Zirconia: Ideal for costume jewelry, temporary placeholders, or fashion accessories where low cost is the primary concern.
• Strontium Titanate: Primarily of interest to collectors of vintage simulants or for use in specialized optical components where high refraction is required without the cost of diamond.

Identification Limits

To the untrained eye, all three can look identical to diamond. However, professional identification relies on specific markers:

1. The “Rainbow” Test: Moissanite displays a distinct double refraction (doubling of facet edges) under a microscope, which is not present in diamonds or CZ.
2. Weight Comparison: CZ is significantly denser than diamond; a CZ stone of the same visual size as a diamond will weigh approximately 1.7 times more.
3. Surface Analysis: Strontium Titanate will show wear and abrasions much faster than the other two, often revealing a “frosted” look on facet junctions.

Related Profiles

For a deeper understanding of diamond alternatives, readers should explore profiles on Lab-Grown Diamonds (which are chemically identical to natural stones) and White Sapphire or White Topaz, which are natural mineral simulants with lower dispersion but higher authenticity.