Answer:
Hardness: Sapphire is one of the hardest gemstones, second only to diamond on the Mohs scale of mineral hardness. It has a rating of 9 on the scale, which means that it is very resistant to scratches and abrasions.
Color: While sapphire is most commonly known for its blue color, it can actually be found in a range of colors, including pink, yellow, green, and purple. The color of sapphire is determined by the presence of trace elements such as iron, titanium, and chromium.
Transparency: Sapphire is typically transparent to translucent, which means that it allows light to pass through it. This property is what gives sapphire its luster and sparkle.
Refractive index: The refractive index of sapphire is relatively high, which means that light is bent or refracted more than it would be in other materials. This is another property that contributes to sapphire's brilliance and sparkle.
Density: Sapphire is a relatively dense material, with a density of around 4 g/cm3. This gives sapphire a substantial weight and feel when worn as a piece of jewelry.