Grading, name of author & beginners books

(Original Forum Question : I am a real shell collector beginner and really I'm looking for some basic information:
– I note there is a grading system as I've seen F and Gem. What is the full grading range and which is best/worst.
– I see often shells for sale or in collections and are shown like this example: Cypraea achatidea (Sowerby 1837). I understand the first two words but what does Sowerby 1837 mean?
– Are there good books (in Engish) for beginners which you would recommend?)

The principle grades are: gem, fine, good, and fair. "Gem" means an absolutely perfect specimen, flawless to the unaided eye. (The whole shell grading system is based on perceptions of "the unaided eye". With a microscope you can find a microscopic flaw on just about any shell, including "gem" specimens.) "Fine" indicates a shell with a rather obvious flaw, which still does not detract greatly from the overall aesthetic or scientific value of the specimen. "Good" indicates a rather severe flaw or several lesser flaws, which does seriously compromise the appearance and/or scientific value of the specimen. "Fair" indicates a shell which no collector is likely to want in the collection, but which still could have some scientific value if it is very rare. A plus sign (+) is used to designate a grade intermediate between the major grades. For example, "fine+" means better than fine, but still not gem. "Fine++" is often used to designate "virtually, but not quite gem". Careful closeup examination of the specimen is required to discover the flaw on a fine++ specimen. Further information can be found here: http://coa.acnatsci.org/conchnet/grad2faq.html The name of a species consists of two latin or latinized words – the genus name (Cypraea), which is always capitalized and always a noun, and the specific name (achatidea), which is not capitalized and is often an adjective modifying the genus name. However, the specific name may also have several other configurations. The binomial name of a species is followed by the surname of the person or persons who originally described the species, and the year it was described.
(Answer by M. Paul Monfils via the Forum)

 (Original Forum Question : What is the difference between "Hwass, 1792" and "Hwass,in Bruguiere,1792"?)

For a new species to be recognized, its description must be published in an accredited publication. "Hwass, in Bruguiere, 1792" means that Hwass first described the species and assigned its name, but his description was first published in a paper written by Bruguiere who, in that paper, identified Hwass as the author of the species description.
(Answer by M. Paul Monfils via the Forum)