Hi, Semi precious stone identification is always problematical simply
because the stones are of lesser value and to that extent fall
outside the scope of gemology and gemological associations. To put it
in an exaggerated way, no one cares very much what you might want to
By that I don’t mean to disparage such stones. In fact, they are
among my personal favorites. The pattern variation in agate for
example is endless and hence always offers fresh possibilities.
The names for agate and jasper tend to be descriptive: plume agate,
moss agate, picture jasper, poppy jasper, fortification agate, lace
agate, etc. Sometimes the geographical location is included in the
name, as in Nipomo tube agate, Morgan Hill poppy jasper. Sometimes
the geographical designation is all you get, as in Montana agate or
Laguna agate from Laguna Mexico.
The best way I can think of to become familiar with these terms and
stones is to frequent the shows. And even then, there’s always
something new, or one person will call his stone a moss agate and his
neighbor will cal;l the same stone a plume agate. In addition to
that, June Culp Zeitner’s “Gem and Lapidary Materials” is a good
reference. Zeitner focuses on the semi-precious to a greater extent
than the Schumann “Gemstones of the World” which has already been
mentioned and which covers both. But if you had to get only one
single reference, go for “Gemstones of the World” - in my view by far
the best and most comprehensive guide.
Ironically the very term semi-precious is frowned upon; the
preferred term is gemstone - precious, three-quarter-precious or
semi-precious, they are all But sem-precious is so much in
the lingo that it will probably never be displaced.