Ring, probably Vatican Mosaic Workshop, Italy, 1825-1875. 97.3.51
The books attached in the bilbiography cover the history of the technique with lots of illustrations -- and few clues about how to make them.
There are also many web resources for studying micromosiacs, for example:
- Laura Hiserote creates amazing micromosaics.
- Cole Sonafrank's website has an extensive discussion of different types of "Mosaic Mortar Formula and Instructions" - primarily for larger work, but he also has an assortment of resources such as a page with to stained glass & mosaic forums and resources as well as information about mosaic mortar.
- Society of American Mosaic Artists Includes lists of workshops & classes, mosaic suppliers, mosaic links, etc.
- British Association for Modern Mosaic: Includes a members gallery, suppliers.
- Mosaic Matters. “The online magazine for all things mosaic. Includes a glossary of mosaic terms, a notice board for questions about mosaics, and pages of hints and tips.