Stones/Gems with O

• Obsidian

  Real volcanic glass; common semiprecious gem.

• Onyx

  Well-known banded chalcedony gemstone.

• OPAL

  Famous precious gemstone with play-of-color.

• Orange Stone
• Olivine

  Real mineral; gem variety known as peridot.

• ornament
• orange calcite
• Old
• octopus
• Oynx
• Oxford
• One
• Oval stone
• Orchid
• Opalo
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• One stone

The words in the list Stones/Gems with O come from players of the word game Categories game.