They seem to feel it somehow makes them more attractive, and enhances them somehow. But it seems to diminish them more. By wearing a fancy and ostentatious piece of jewelry, they become an adjunct to it rather than the other way around.
(When some woman proudly flashes a big diamond engagement ring, I always have to repress a desire to tell her, "You remind me of Gollum in Lord of the Rings.")
In a way, it's a roundabout admission of failure: there's really nothing to admire about me, so, please, admire my jewelry instead.
An expensive watch sends the same message, since these days cheap watches tell time just as well. (Both Rolexes and Omegas are, in spirit, far more pieces of jewelry than timepieces.)
A woman who gets extremely excited over a pricey engagement ring is basically saying: my value has been affirmed! A man values me this much!
(Have you no self-worth?)
In general, the more expensive the jewelry, the cheaper the woman. Such women don't care how witty, or smart, or honest, or decent you are. They only want to know how successful you are. More important than that, how much money you have. And even more important than that, whether they can get their hands on any of your money.
(If you're a stupid-but-rich sociopath, these are the women for you.)
A woman who loves jewelry is apt to see a short, fat, ugly, well-dressed, conceited guy get out of a Ferrari and think to herself, wow, that guy is really sexy. Jewelry-lovers aren't necessarily quite as conniving as gold-diggers, but they do tend to conflate money with sexual attraction.
If having a fancy car or big house is ostentatious, wearing expensive jewelry is ten times more so. It's basically the equivalent of taking a thick wad of hundred dollar bills, encasing them in sheer plastic, and hanging them around your neck.
And if women who wear gaudy jewelry are off-putting, men who wear jewelry are even more so.
What men have traditionally worn flashy jewelry, like gold chains and pinkie rings? Mafiosi.
These days, the gangsters have been surpassed in that department by gangstas.
And gangstas have been outdone by those pretend gangstas, the rappers who have renamed such ornamentation "bling."
In all three cases, the mentality is the same: admire me for my strutting ostentation (....since there is little else to admire me for.)
Just remember, the next time you consider buying a piece of jewelry -- even one piece -- you're taking a step in the direction of Flavor Flav: