Steven DiFranco Jewelers

December Birthstone - Blue Zircon or Tanzanite


Although thought by many to be relatively new to the gem market, zircon has been with us for many centuries. In the Middle Ages zircon was worn to promote riches, honor and wisdom.  It was also believed to drive away plagues and evil spirits.

The name is believed to originate from the Persian word "Zargun", which means "gold colored", due to the yellow color of the stones found there.

Blue Zircon gained popularity in the 1880's and was used extensively in Victorian jewelry. In fact, jewelry from this period is a principal source today of blue zircons over five carats.

  • Specific Gravity: 3.93

  • Refractive Index: 1.810-1.984

  • Hardness: 6.5-7.5
  • Zircon Color: Bluish Green, colorless, yellow, brown, orange, and red, violet.

  • Countries of Origin: Burma, Cambodia, Sri Lanka, Thailand, Australia, Brazil, Korea, Madagascar, Mozambique, Nigeria, Tanzania, and Vietnam.

  • Wedding Anniversary: 7th year

Wearing Conditions: Blue Zircon can be sensitive to impact.

Cleaning Conditions: Blue Zircon can be cleaned in both ultrasonic and store bought cleaners, but not for an extended period of time.


Steven DiFranco Jewelers


Tanzanites have a bluish purple that is tough to describe.  That's probably why they've been so popular for years.

  • Specific Gravity: 3.35

  • Refractive Index: 1.691-1.700

  • Hardness: 6.5-7stone can be re-polished to restore its sparkle.  With normal wear, a tanzanite would need it's top surface repolished every 3-5 years.  With careful wear, this can be considerably longer.
 Cleaning Conditions: Can be cleaned by ultrasonic with EXTREME caution considering how delicate tanzanites are. Cleaning by soft brush and warm water is preferred.