Moissanite has become a highly popular material in the jewelry industry, often serving as an alternative to traditional gemstones. This crystalline compound, known scientifically as silicon carbide (SiC), is valued for its brilliance and durability. Its structure consists of silicon and carbon atoms held together by strong covalent bonds. Understanding hardness is paramount for any material intended for daily wear, as this characteristic determines its long-term appearance and longevity.
How Gemstone Hardness is Measured
The hardness of a gemstone refers to its resistance to scratching or abrasion on its surface. Mineralogists quantify this property using the Mohs Scale of Mineral Hardness, developed by German mineralogist Friedrich Mohs in 1812. The Mohs scale ranks minerals from 1 (Talc) to 10 (Diamond) based on the principle that a harder material can visibly scratch a softer one.
This is an ordinal scale, meaning the numerical intervals are not linear. The difference in absolute hardness between a 9 and a 10 is far greater than the difference between a 1 and a 2. This system provides a practical way to assess a mineral’s scratch resistance and wearability.
The Specific Hardness Rating of Moissanite
Moissanite achieves an exceptionally high rating on the Mohs scale, scoring 9.25. This number places it among the hardest known substances, ensuring a high degree of scratch resistance. This exceptional hardness is a direct result of the silicon carbide crystal structure.
The strong covalent bonds between the silicon and carbon atoms create a robust and dense crystal lattice. This atomic structure requires a significant amount of energy to disrupt, making the surface highly resistant to abrasion. The 9.25 rating signifies that moissanite is well-suited for everyday jewelry, as it can withstand the constant friction of daily life without easily developing surface scratches.
Scratch Resistance Compared to Common Gemstones
Moissanite’s 9.25 rating is second only to diamond, which holds the top spot at 10 on the Mohs scale. This narrow difference has practical implications for long-term wear, as only a diamond can scratch moissanite.
The high score of moissanite is significantly greater than other popular colored gemstones. For instance, Corundum, which includes both sapphire and ruby, ranks at 9. Moissanite is also substantially harder than Topaz, which rates an 8.
Moissanite’s hardness of 9.25 is particularly advantageous when compared to Quartz, which is rated at 7. Since Quartz is a common mineral found in household dust and sand, any gemstone below a 7 is highly susceptible to scratching from airborne particles. Moissanite’s position well above this threshold means it can resist abrasion from the abrasive dust that settles on jewelry, helping to maintain its polished finish over decades of use.
Durability Factors Beyond Surface Hardness
Hardness, or scratch resistance, is only one of the three components that determine a gemstone’s overall durability. A complete assessment of wearability must also consider toughness and chemical stability. Toughness refers to the material’s resistance to fracturing, chipping, or breaking when subjected to a sudden impact.
Moissanite exhibits excellent toughness, which is a significant factor in its suitability for rings and other exposed settings. Its crystal structure lacks the distinct cleavage planes found in materials like diamond, making it potentially more resistant to chipping from a sharp blow. Moissanite also possesses high chemical and thermal stability, resisting damage from common household chemicals and the extreme heat involved in jewelry manufacturing and repair processes.