Corundum (noun)

1. A crystalline form of aluminum oxide that is a mineral and a valuable gemstone.
2. A naturally occurring mineral that is a form of aluminum oxide and can be found in various colors including red (ruby), blue (sapphire), and colorless (white sapphire).

Origin:

From the tamil word 'kurundam' meaning 'ruby'.

Examples:

1. The corundum was valued for its beauty and rarity.
2. The corundum was used in jewelry and other decorative objects.
3. The red corundum is known as a ruby.
4. The blue corundum is known as a sapphire.
5. The colorless corundum is known as a white sapphire.