Other
The image.com: Minerals
This is a very large list of minerals complete with image and physical descriptions, chemical descriptions, and classification.
Jewelry Central
Jewelry Central: Ruby
This commercial site gives information on rubies, including their physical properties and where they are found. Includes some details on how to choose a ruby for purchase.
Amethyst Galleries
Amethyst Galleries: Mineral Gallery: Ruby
This site gives general information about the gem, ruby. Also included is information about hardness, color, uses, and other physical characteristics
Other
International Colored Gemstone Association: Ruby
Site provides many facts about rubies, including properties and where rubies are found. Also provides further information and pictures of the gem itself.
Amethyst Galleries
Amethyst Galleries: Mineral Gallery: Sapphire, the Non Red Variety of Corundum
This resource provides general information on sapphire, including hardness, color, and uses.
Curated OER
The image.com: Minerals
This is a very large list of minerals complete with image and physical descriptions, chemical descriptions, and classification.