Learning about medieval jewelry
http://www.ceu.hu/medstud/manual/SRM/jewel1.htm
http://neurolanis.tripod.com/id20.html
http://www.jjkent.com/articles/jewelry-guide-vol1/index.htm

Learning about gemstones
http://www.gemstone.org/
http://www.gemsociety.org/info/info.htm#gemology

Learning about birthstones
http://www.about-birthstones.com/decemberbirthstone.html

Some historic treasures
The Fishpool Hoard
http://www.thebritishmuseum.ac.uk/compass/ixbin/goto?id=OBJ11440
The Cheapside Hoard
http://www.ganoksin.com/borisat/nenam/cheapside-hoard.htm
The Thetford Treasure
http://rubens.anu.edu.au/new/england/london/museums/british_museum/
The Snettisham Jeweler's Hoard
http://www.thebritishmuseum.ac.uk/compass/

The Treasure Act and archaeological finds
www.finds.org.uk

Becoming an expert: Gemological Institute of America
http://www.gia.edu/ /

Order antiquarian books about rings
www.jmcohenrarebooks.com/