In Chinese culture, qualities associated with 坚硬 are often highly valued. While in the West, being “hard” can sometimes imply being unfeeling or stubborn (“hard-headed”), in China, 坚硬 more frequently evokes positive concepts like resilience, integrity, and perseverance. It's culturally linked to the image of bamboo (flexible yet strong) or jade (a hard, precious stone symbolizing purity and virtue). A person with a 坚硬 will is seen as reliable and steadfast, able to endure hardship (吃苦, chīkǔ) without breaking. This contrasts with the Western concept of “stubbornness,” which is almost exclusively negative. 坚硬 is closer to the English “rock-solid” or “steadfast”—a desirable trait for facing life's challenges. It embodies the strength needed to remain true to one's principles in the face of pressure.
坚硬 (jiānyìng) is slightly more formal and descriptive than its common counterpart 硬 (yìng). You'll find it more often in written Chinese, formal descriptions, and when someone wants to emphasize the extreme hardness of something.