Black Diamond Care and Maintenance: The Definitive Guide
Black diamonds are the hardest natural substance on Earth, but their polycrystalline structure introduces care considerations that do not apply to colorless stones. Here is what every owner needs to know.
Understanding the Polycrystalline Structure
While black diamonds score 10 on the Mohs hardness scale — the same as colorless diamonds — their polycrystalline nature means they are structurally different. A single-crystal diamond has defined cleavage planes, making it predictably strong in some directions and vulnerable in others. Carbonado, with its interlocking crystal matrix, is actually more resistant to cleavage — but the graphite-filled pores that give it its color create microscopic porosity that requires specific care.
Cleaning
Clean a black diamond with warm water, a small amount of mild dish soap, and a soft-bristled brush (a dedicated jewelry brush or a clean, soft toothbrush). Gently scrub the stone and setting, rinse thoroughly with clean warm water, and pat dry with a lint-free cloth.
Avoid ultrasonic cleaners for black diamonds. The vibrations can cause stress fractures in the polycrystalline matrix, particularly in stones that already have visible grain boundaries or surface porosity. Steam cleaners should also be avoided for the same reason.
Storage
Store black diamond pieces individually, wrapped in a soft cloth or in a separate compartment in a lined jewelry box. Despite their hardness, black diamonds can scratch other gemstones and be scratched by the settings of other diamond pieces. Individual storage prevents surface contact damage.
Avoid storing black diamonds in extreme temperature environments. While the diamond itself is thermally stable, repeated thermal cycling can eventually stress the bond between the stone and its setting — particularly in bezel and channel settings where the metal expands and contracts around the stone.
Wear and Handling
Black diamonds can be worn daily, but common-sense precautions apply. Remove jewelry before activities involving heavy impact, chemicals (including household cleaners, chlorine, and hair products), or abrasive surfaces. When not worn, secure the piece in its storage case.
Inspect the setting periodically — every 12 months at minimum — for any loosening of prongs, wear in bezel edges, or movement of the stone. The polycrystalline nature of black diamonds means a loose stone in a prong setting faces higher risk than a single-crystal diamond of the same size, as the stone's surface may provide less grip.