Can lab-grown diamonds crack?
No, lab-grown diamonds do not crack easily. As the hardest substance on earth, they are extremely durable and resistant to fracturing, just like mined diamonds.
Lab-grown diamonds, also known as cultured or created diamonds, are chemically and structurally identical to mined diamonds. They are produced by replicating the high-pressure and high-temperature conditions under which diamonds form naturally deep within the Earth. The key difference lies in the controlled laboratory environment, which allows for meticulous control over the diamond growth process, atom by atom.
This level of precision enables producers to minimize flaws and create diamonds with exceptional clarity. With fewer atomic defects, lab-grown diamonds tend to be even harder and more crack-resistant compared to many mined diamonds of similar size and cut. However, they are still not completely immune to cracking under extreme conditions.
At 10 on the Mohs scale, a diamond's hardness is surpassed only by its own crystallized allotrope, aggregated diamond nanorods. Though extremely hard, forceful impacts can still cause fractures. Cleaving along the diamond's four perfect octahedral cleavage planes requires very focused pressure. This tendency to cleave gives diamonds their sharp edges as cutting tools. Heat and rapid temperature changes can also introduce cracks.
Comparison of material properties:
| Material | Hardness (Mohs scale) | Fracture toughness |
|---|---|---|
| Lab-grown diamond | 10 | 5.8 MPa√m |
| Cubic zirconia | 8.5 | 4-6 MPa√m |
| Moissanite | 9.5 | 2.3 MPa√m |
| Silicon carbide | 9.5 | 3-5 MPa√m |
Other superhard materials sometimes used as diamond substitutes, like cubic zirconia, moissanite silicon carbide, cannot match a diamond’s crack resistance due to their fundamentally different atomic arrangements. Though the lattices of these minerals are tightly bonded, they contain more defects, dislocations, and grain boundaries compared to a perfect lab-grown diamond crystal.
In summary, while not completely unbreakable, the precisely engineered structure of lab-created diamonds makes them exceptionally durable and resistant to cracking - matching or even surpassing the fracture toughness of natural diamonds. They do not break easily!