What is a notable physical property of Kashmir sapphires?

Kashmir sapphires are celebrated for their unheated quality, which is one of their most defining characteristics. Unlike many other sapphires that undergo heat treatment to enhance their color and clarity, Kashmir sapphires are often found in a natural state, preserving their original hues without artificial enhancement. This unheated quality contributes significantly to their value and desirability among collectors and gem enthusiasts.

Additionally, the color of Kashmir sapphires is renowned for its depth and richness, typically described as a velvety blue, which is attributed to the unique geological conditions of the region where they are mined. The absence of heat treatment allows these stones to retain their original color characteristics, making them particularly sought after in the marketplace. The provenance and rarity of unheated Kashmir sapphires further enhance their prestige in the world of colored gemstones.