Description

A pink to blood-red colored gemstone, a variety of the mineral corundum (aluminum oxide). It is one of the hardest natural minerals.

Description of what it is like

Hard, crystalline stone with a red hue. Transparent to translucent.

Origin and where to find it

• Natural: Found in marble layers, basalt, or alluvial deposits (riverbeds).
• Synthetic: Can be created in labs (flame fusion) for industrial use.

Minimum processing required

• Cutting/Polishing: To shape for jewelry or bearings.
• Drilling: For use as watch jewels (requires diamond dust).

Tools needed to work on it

• Diamond tools: Only diamond is harder and can cut/polish ruby effectively.

Common forms of use

• Jewel Bearings: Tiny donuts of synthetic ruby used to reduce friction in watch gears.
• Gemstones: Cut and polished for ornamentation.

Possible substitutes

• Sapphire: Another variety of corundum, identical properties but different color.
• Glass: Much softer, wears out quickly.
• Brass/Bronze: Metal bushings (higher friction than jewels).

Limitations and common failures

• Brittle: Can chip or shatter upon hard impact despite hardness.

Risks and safety

• None: Chemically inert and safe.