I don’t like any jewellery. Don’t like gold or silver or gemstones or dangly things hanging from body parts of any kind.
Diamonds are over-valued because of monopolies in the diamond trade. They aren’t nearly as precious as most people think they are.
And after all, when you can buy something that looks for all intents and purposes the same for a lot less, why throw away your money?
Oh. Sorry. You need to tell the world how much money you have.
I’m not anti- or pro-. They’re kinda “meh” to me. I prefer them as an accent stone with other stones, like garnet, amethyst, sapphire, emerald. I wouldn’t hate a piece of diamond jewelry, but it wouldn’t be my favorite.
I’m not really a fan of any sparkling gems at all, especially ones with inflated prices and sketchy human rights records. I much prefer smooth stones with interesting inclusions and streaks, like jade, turquoise, or amber.
I’ll just agree with what everyone else said. I find diamonds aesthetically boring and morally suspect. I prefer blue gems such as aquamarine and sapphire, or plain jewelry with interesting filigree or engraving.
I like the look of diamonds, but there is absolutely no good reason to spend $$ on them as opposed to moissanite. Jewelers have a very hard time telling the difference between moissanite and diamonds with the naked eye.
Cute anecdote: I’ve worked at a jewelry store and was 
occasionally when a veteran worker had a prodigious talent for guessing moissanites from diamonds. She seemed to be right a lot (wasn’t a trained jeweler), and I asked how she could tell the difference. The answer: she just looked at the clothes the client wore… :eek:
A really GOOD diamond (large, $$$) can be quite pretty. But for most I’ve never seen the allure, myself.
I prefer things with deep color. Opals are nice, especially fire opals.
http://www.astral-creations.fr/catalog/images/cabochon%20carre%2012x12mm%20fire%20opal.jpg
But hey, I’m easy. Even Tiger Eyes, which aren’t worth much, are pretty.
http://oldenwisdom.com/images/tigereye.jpg
OK, I gotta pick? A nice star ruby, I think.
http://www.thaigemshop.com/contents/media/t_star-ruby-1319-1.jpg
I dislike them, most because I dislike the marketing and hype around them. The geniuses at DeBeers have made spending a small fortune on a not-particularly rare stone somehow become the same thing as love. People are free to waste their money as they want, but damned right I’m gonna judge them when they do.
I’ve been interested in minerals and gems nearly all my life, so I do like gems in general. But I’m not a huge fan of diamonds, and think they tend to get all the attention concerning gems. (They do account for something like 90% of the gem trade in monetary terms.) A top quality amethyst, which is about 99% cheaper, can be more striking than a diamond in my book. Recently I had the opportunity to examine a square-cut aquamarine about the size of my thumbnail, and it was absolutely stunning. Aquamarines tend to be a little dull and glassy, their main attracting being the color, but this one was brilliant. It wasn’t a cheap stone–the ring was being offered for about $2000 IIRC, but it was far cheaper than it would have been if that were a diamond.
I don’t like 'em at all. I owned/operated a jewelry studio for three years shortly after I got out of college, and I’d always use white sapphires when a piece demanded a sparkly white accent stone.
I don’t dislike them, but I never really cared if I owned one or not. I do now, in my wedding ring set. If I did get a diamond, I didn’t want a round one…those I do find very boring. Hubby picked out a pear shaped stone. It isn’t real big, and if I can lose weight or get it sized, I will wear it again. I haven’t been able to wear it since the birth of my son five years ago.
The ring I wear daily is a very simple Amethyst ring set in gold. It is my birthstone and one of my favorites. I don’t own any, but I would love an emerald or a really red ruby some day. But it isn’t high on my priority list. I am not much into jewelry anymore. I used to wear it a lot more 20 years ago.
Over-done and boring. Give me something with color anyday. The only thing about diamonds, though, is that they hold up better than other stones. Colored diamonds exist, but they’re pretty rare and more expensive.
Opals are gorgeous, but unfortunately, they’re really soft. 
I do, however, wear my grandmother’s engagment ring almost everyday. It’s silver, and the diamond is small, with another band, set with a line of several other very small diamonds. It’s very 1930s looking. (My grandparents got married in '47). I like mostly vintage jewelry.
Wow, lots of people here share my taste for iridescent cabochon pretties! Diamonds seem so cold and hard, like ice you could cut yourself with. I have a hard time justifying the purchase of jewelry I really do like - money could be spent on books or art supplies instead. In fact I haven’t got an engagement ring, we’ve got plain sterling wedding bands (not crazy about gold either.) I felt pretty lucky to marry a guy who was fine with me not wanting to broadcast his prowess with a display of sparkly carbon. I daresay he felt a bit relieved too!
Also not a big fan. I prefer gems with darker, richer colors.
I also don’t like them and I can never get past how often they are connected to funding conflict or being harvested by slave labor.
I like diamonds, especially some of the fancies, but not more than sapphires or amethyst.
Another one who doesn’t give a damn about diamonds and would be happy never to own one (if I didn’t already, in the form of an antique emerald-and-diamond cocktail ring that my grandmother, who was in the antique business, gave me from her own jewelry box). Now what I really miss is a gorgeous antique deep blue sapphire ring in a white gold filigree setting that my grandparents also gave me. It was stolen, along with all the other jewelry they had given me until then, in a burglary nearly 20 years ago. If I ever end up with an engagement ring, I hope it will be something in that spirit.
I don’t dislike diamonds, but I think they’re pretty overpriced and boring. Give me a nice sapphire any day!
Diamonds are pretty but overpriced. So is moissanite. Give me a few CZ’s when I’m in that mood! Colored stones are my favorites.
However, for those who are too pure to touch diamonds: What do you know about the labor conditions that produce the other gemstones? Precious metals, too…
I’m pretty into synthetics, actually. It has nothing to do with the fact that they’re also cheaper…
Seriously, I would love to see an in-depth reveal of labor and environmental conditions for various gemstones. And also for synthetics – for all I know, creating the pretties releases clouds of toxic gasses that make Bambi cry.