Jade is a gemstone valued for millennia across various cultures for its ornamental and artistic uses. Its appeal stems from its rich color, texture, and notable physical properties, especially its resistance to wear. Understanding how jade holds up to daily use requires consulting the Mohs Scale of Mineral Hardness, which measures a material’s scratch resistance. This scale provides a framework for assessing the relative durability of jade compared to other common materials.
Defining Nephrite and Jadeite
The term “jade” does not refer to a single mineral but rather to two distinct mineral species: nephrite and jadeite. These two materials are chemically and structurally different, which results in variations in their final physical properties, including hardness. Nephrite is classified as a calcium and magnesium-rich amphibole mineral, forming a composition that is an aggregate of tremolite-actinolite. This composition creates a dense, matted structure of interwoven fibrous crystals that contributes to its physical characteristics.
In contrast, jadeite is a sodium and aluminum-rich pyroxene mineral, which is considerably rarer than nephrite. Jadeite’s internal structure is composed of interlocking, fine-grained crystals rather than the fibrous arrangement seen in nephrite. Both of these distinct structures are microcrystalline, meaning their individual components are extremely small and tightly packed. This unique formation is the reason why both nephrite and jadeite possess their characteristic toughness.
The Specific Hardness Rating
The Mohs Scale of Hardness ranks minerals based on their ability to scratch one another, ranging from 1 (talc) to 10 (diamond). This scale measures resistance to scratching, which is a different property from resistance to breaking or chipping. Jadeite consistently ranks slightly higher on this scale than its counterpart, with a hardness that falls between 6.5 and 7.0.
Nephrite has a slightly lower hardness rating, typically measuring between 6.0 and 6.5 on the Mohs scale. To provide context, steel files and common window glass generally have a hardness around 5.5, meaning both forms of jade resist scratching from these everyday items. However, the omnipresent mineral quartz, a major component of common dust and sand, has a hardness of 7.0. This means that most jade, especially nephrite, is susceptible to surface damage from repeated exposure to quartz-rich grit and airborne particles.
Durability and Care for Jade Jewelry
While hardness measures a gemstone’s resistance to scratching, durability also depends on its toughness, which is the resistance to breaking or chipping. Jade is celebrated for its exceptional toughness, a property that is particularly high in nephrite due to its interwoven fibrous crystal structure. This dense, felt-like arrangement allows nephrite to absorb impact and resist fracturing better than many harder stones, such as quartz or even topaz. Jadeite is slightly less tough than nephrite but still possesses a superior resistance to shattering compared to most other gemstones.
Translating these properties into care requires specific practices to protect the stone’s surface from scratches. Jade jewelry should be stored separately from harder gems like sapphires, rubies, and diamonds, which will easily abrade its surface.
Cleaning and Maintenance
For cleaning, the safest method involves using only mild soap and lukewarm water, gently applied with a soft cloth. Avoid steam cleaners and ultrasonic cleaners, especially if the jade has been treated, as the heat or vibrations can potentially damage the stone or its setting. Furthermore, jade should be protected from harsh chemicals, like household cleaners and chlorine, which can dull the polish.