The birthstone for January is Garnet, a semiprecious stone that is a deep red.
Garnet is the gem stone listed for the entire month of January.
You may also add Apache Tear, Diamond, Falcon's eye, Hematite, Jet, Onyx, Ruby, and Topaz if you are a Capricorn (Jan 1st to Jan 19th) and Amazonite, Amber, Aquamarine, Hematite, Jet, Onyx, Sapphire, Topaz if you are an Aquarius (Jan 20th to 31st).
Traditional, Modern and Ayurvedic Birthstones for January: Garnet
Mystical Birthstone for January: Bloodstone