Ruby (noun)

1. A precious stone, typically red in color, which is a variety of the mineral corundum (aluminium oxide).
2. A transparent deep red variety of corundum, valued as a precious stone.

Origin:

Middle english: from old french rubi, via latin from greek rhúbos "red".

Examples:

1. The ring had a large ruby in the center.
2. The necklace had many small rubies on it.
3. A ruby is a precious stone.
4. The ruby is the birthstone for July.
5. The ruby is a symbol of love and passion.