kw: book reviews, nonfiction, gemstones, mineralogy, history
Strictly speaking, jewels and jewelry are not limited to gems, but without gemstones, jewelers would need to be a lot more creative. In Jewels: A Secret History by Victoria Finlay we find the author on a nine-part quest, to learn the history, mythology, mineralogy, and some gemology for the four "precious stones": diamond, sapphire, ruby, and emerald, plus five other gem materials that, at one time or another, have been deemed precious enough for a king's ransom.
Basically, "precious" gems are those that are harder than the tip of a penknife (for durability), clear enough that faceting (rather than form into a cabochon) enhances their beauty, and rare enough that the market for their production can be cornered by a small number of powerful folks. These days, we add one more proviso: stones formed by natural means carry a better cachet than those formed in the laboratory.
Interestingly enough, some gems violate these guidelines yet retain popularity and value. For example, Amber, Jet, Pearl, and many Opals are softer than a Moh's hardness of 5.5, so a pocketknife will scratch or cut them; Jet and Pearl are partly or wholly opaque; and Diamonds are more common than Garnet, Spinel, and Zircon. The four "soft" gemstones are just too beautiful to pass up, and ditto the opaque and semiopaque ones. Diamond's rarity is artificially maintained by a cartel of mining-and-distribution companies, who have recently even begun producing laboratory-grown gems in an effort to enclose that market also. Without the cartel, diamond values would be in the few-hundred-dollar-per-carat range...and that's about what they go for at a pawn shop.
Ms Finlay's travels took her from Poland to Yorkshire to Sri Lanka to Africa, and quite a few other places (nice work if you can get it). In nearly every case, she found that the historical mines have been supplanted by newer, better ones, which has usually led to a decreased market value for the gems in question. Today, many "middle class" folks can afford gemstone jewelry, forcing richer folk who wish to display their riches with some "bling" to obtain ever-more-extravagant large stones in imaginative settings.
It is still the case, however, that those who actually mine the more precious stones are among the poorest people, working in abysmal conditions. Only diamond miners have had a meaningful improvement in their work conditions and prosperity in recent years. Most mining is still carried out by poor men (and a few women) working in hot, wet (or both) holes that frequently fall in on them.
The book is arranged by hardness of the gem material, from soft amber to diamond. The traditional precious gems are all hard, 7.5 and harder (diamond is 10, but on a more "true" scale would be about 40), so they come in a cluster in the end of the book. Topaz, also an 8, is not mentioned. I guess I don't find this strange. It cleaves too readily, and is hard to cut without getting "pull marks" on the table unless one REALLY knows how to set the crystal axes beforehand.
Jewels is a lot of fun to read. I am a rock junkie. Though my personal interest is in semiprecious stones, mostly the incredible range of chalcedony gems, I've known a few hobbyists who produce faceted gems. None that I know try to do diamonds; most do quartz in various colors, and a few have done sapphires. It takes a certain, almost obsessive, personality to produce a faceted stone. Me, I like the "natural facets," the crystal faces, of well-grown mineral specimens. I'll "silver pick" any clear gems I might wish to own.
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