Sphene, also known as titanite, is a rare and beautiful gemstone prized by collectors and jewelry enthusiasts for its striking brilliance and unique optical properties. Here’s a detailed description:

General Characteristics

• Chemical composition: Calcium titanium silicate (CaTiSiO5), often with traces of iron, aluminum, and rare earth elements.

• Crystal system: Monoclinic.

• Color: Can range from yellow, green, brown, orange, reddish, or even black; green and golden tones are the most valued.

• Luster: Adamantine to sub-adamantine, giving it a bright, almost diamond-like shine.

• Transparency: Transparent to translucent.

Optical Properties

• Dispersion: Very high (greater than diamond), giving sphene extraordinary “fire”—the colorful flashes of light seen when the stone is moved.

• Refractive index: 1.84–2.11 (relatively high, contributing to its brilliance).

• Pleochroism: Often strong, showing different colors when viewed from different angles.

Physical Properties

• Hardness: 5–5.5 on the Mohs scale (softer than quartz, making it relatively delicate for jewelry use).

• Specific gravity: 3.4–3.6.

• Cleavage: Distinct, which can make cutting and setting challenging.