Month 12 · gemstone almanac
December
birthstone
Tanzanite is the blue-to-violet gem variety of zoisite. Its principal commercial source is the Merelani mining area in northern Tanzania. The gem is pleochroic, showing different colors from different viewing directions, and heating is commonly used to develop its blue color.
Share the December birthstone guide
Immediate answer
Tanzanite and Turquoise and Zircon
- Modern list
- Tanzanite · Turquoise · Zircon
- Traditional list
- Turquoise · Lapis lazuliA different stone from the modern list
- Hardness
- 6-7 on Mohs scale
- Reference policy
- Primary sources over folklore summariesAlternatives remain visible when a source lists them
Which list are you being given?
December has two defensible answers
Most pages that answer “what is the december birthstone” quote one list without saying which. There are two in common use: the modern American list standardised by the National Association of Jewelers in 1912 and revised since, and the older traditional list that preceded it.
| List | Stone(s) for December | Basis |
|---|---|---|
| Modern | Tanzanite, Turquoise, Zircon | Standardised in 1912 and maintained since; used by current gemological guidesThe list this site leads with |
| Traditional | Turquoise, Lapis lazuli | Older lists predating the 1912 standardisationStill widely quoted, especially outside the United States |
What changed: Turquoise and lapis lazuli are the older December stones. Zircon was added in 1952 and tanzanite in 2002, which is why current guides lead with tanzanite.
The modern list was designed around transparent, faceted gems so that jewellers could set several children's stones in one ring. That commercial motive, not a gemological discovery, is why some months changed. Later revisions added alexandrite and citrine in 1952, tanzanite in 2002, and spinel in 2016.
Neither list is more “correct”: a birthstone assignment is a published convention, not a property of the gem or of the month. If a gift matters, ask which list the recipient grew up with.
Gem facts
Identity, color, and durability
Tanzanite is the blue-to-violet gem variety of zoisite. Its principal commercial source is the Merelani mining area in northern Tanzania. The gem is pleochroic, showing different colors from different viewing directions, and heating is commonly used to develop its blue color.
- Names in use
- Zoisite · Blue-violet Zoisite
- Mohs hardness
- 6-7 on Mohs scale
Typical color palette
- #6B3FA0
- #4169E1
- #9370DB
- #483D8B
Symbolic tradition
Meanings and crystal traditions
Tanzanite symbolizes transformation, spiritual growth, and new beginnings. As one of the newest gemstones discovered, it represents the modern age while its deep blue-violet color evokes mystery and magic.
- Modern crystal traditions associate tanzanite with transformation
- Its blue-violet color is often linked with intuition and reflection
- New Age readings use tanzanite as a symbol of spiritual connection
- Some symbolic practices connect it with communication
- These interpretations are traditions, not scientific effects
Interpretation label: Personality words such as intuitive, transformative, spiritual, unique, perceptive belong to symbolic birthstone readings. They are not traits caused by a gemstone or birth month.
Context
History and cultural variations
Blue zoisite from Tanzania was identified in 1962, and prospectors located its primary Merelani source in 1967. Tiffany & Co. later promoted the gem under the name tanzanite, honoring its country of origin.
New life, given to newborn children
Unique engagement stone alternative
Stone of transformation and spiritual growth
Considered a 'generational gemstone'
Variation note: Historical beliefs are presented as beliefs. A source can document a tradition without proving a physical or medical effect.
Practical guide
Jewelry care and gift ideas
- Clean gently with warm soapy water
- Avoid ultrasonic and steam cleaners
- Protect from hard knocks (softer than sapphire)
- Store carefully away from other gems
- Avoid extreme temperature changes
Care note: Treatments, inclusions, and settings can change safe cleaning methods. Ask a qualified jeweler when a stone's treatment history is unknown.
Budget ideas
Small tanzanite pendant · Tanzanite accent ring · Tanzanite studs
Mid-range ideas
Tanzanite solitaire ring · Tanzanite drop earrings · Tanzanite bracelet
Premium ideas
Large tanzanite statement piece · Investment-grade tanzanite · Custom tanzanite design