Best Coasters EVER at first; not so any longer.
348374
In my original review a few weeks ago (Dec. /16) see below, I gave these a five star and a glowing review.  Now that I've used them every day for over a month, I changed my opinion and am giving them only a three star; reason is that when I first started using them, with a glass of water with ice and left it on them for hours, the condensation off the glass soaked right into the coaster and left zero water pooled on them; that lasted for only about two weeks or so; after that, leaving the same glass of water with ice on the coasters, the condensation water off the sweating glass pools on top of the coaster right away and does not soak in at all.  This is very disappointing, since they now act just like all other coasters leaving pools of water.  And, it is NOT because too much water got soaked in the coaster and it couldn't handle any more; they do not absorb any water now, not even a little bit, when the coaster is completely dry.  And that's the sole reason I bought these (and they're over priced as it is); not happy.  So buyer beware.  (See below for my first review; wish it was still the case.)

First Review in Dec. '16:  These coasters are the very best.  They are pretty, but most important is that they actually absorb the best of any I've ever tried.  I left a glass full of water and ice on one of them for 3 hours; when I came back, the glass sweated a lot, but it was all absorbed and there wasn't a pool of water on the coaster under the glass; fabulous !!  And the cork on the bottom is an added plus.
2097362
I like coasters that will not need a lot of cleaning and not leave moisture on the table.  These are simply the best.  Love them.  We get lots of compliments of their unique design.
4000504
I would not recommend these coasters.  We have had them 2 years and bought them because they matched our dinner ware.  These coasters stick to the bottom of glasses when the glasses start to sweat and then when someone picks up the glass the coaster comes with it then drops in your plate of food.  It has happened many times.  And when they fall to the floor they break.  Waste of money.
1844234
I THOUGHT that these were excellent when I received them- I even wrote a 5 star review!  They looked great, and seemingly were a solid deal.  Fast forward to 2 months later, and I notice black stuff creeping up on the rings.  I tried to clean it, and it was impossible.  Soon enough it became obvious that this black "stuff" was mold, and it was on all of the coasters.  Also, they all became warped, which is not a desirable coaster feature.

These were used in an adult only home, once a day or less, and were immediately dried after use.  Do not buy these if you actually need to use your coasters.
3258528
The rubber bumpers didn't feel stable, so I took them off. Had a glass of water on one of these coasters for an hour, and it left a huge stain. Use without the bumpers at your own risk :(
1715979
Coasters were not cork. They were spongy like a mouse pad.
789921
I really liked the way these look, but unfortunately, they don't do the job a coaster is ultimately supposed to do...protect the surface upon which the coaster and drink rest.  The perspiration from cold drinks pools on the coaster, and eventually, makes its way down the edges and onto the counter/table/desk.  Sorry guys, but this is a bust.
4505347
These coasters are great! They might seem pretty pricey for coasters but you definitely won't need to worry about replacing these anytime soon.

Pros:
- There wasn't a strange smell/odor right out of the box.
- The lip is also great for keeping any fluids contained and off of your table.
- In a nutshell, they're unassuming, very easy to clean and extremely durable.

Cons:
- I did notice that dust/lint seems to stick pretty easily to the surface but hopefully that goes away with time.

Going to be buying another set soon!
1330900
I used the entire 10 pack to make several 3D Blu-ray movies and all turned out fine.  Not one coaster.  Not one that couldn't handle the 50gb's of data.  Extremely pleased.  In fact I am ordering more as I type.  Wish they sold in 50 packs.
Update.  I got the second pack of 10 and all but one worked.  One failed due to hardware failure so not sure we can blame on disc.  So one of 20 failed in the end.
4660513
This is a great Hi-Q novelty gift for anyone in the neural field, but these fragile, untextured museum-quality glass coasters cling to any other glass surface with even a little bit of moisture. Not a good characteristic for a coaster: I fumbled one off the coffee table while moving an icy tumbler, and that 18" drop to the floor shattered it to pieces. Not easy gemlike tempered pieces, either; it turned into those sharp, nearly invisible shards of all sizes that are so hard to clean up.

I ordered a second set to replace the slide I broke, and those which we will probably continue to break. But that's a mixed criticism; if they weren't so cool, I wouldn't have bothered. It's a pretty authentic miniaturized replica of the human brain. If you look at the stacked set of coasters from the side, you can make out the major brain structures in 3-D. Clever product, even if not so practical.
2888474
These are beautiful coasters with a great Celtic knotwork design.  They do their job well, but they are only some sort of composite "plastic" type resin.  There are others out there that are some sort of moisture-absorbing stone, but these particular ones don't absorb any kind of moisture.  The moisture just ends up sitting on top of the coaster and settling into the nooks and crannies.
2513313
3 years later, and the outer surface layer is breaking down just like the originals did. Fancy looking black bits now fall off of of the pads. (Hint: They aren't fancy at all)

While they worked pretty well until they started breaking down, I'm buying something else this time around.
4855555
I can't lie.  I've had some coasters and it's disappointing when it happens but I also have had a good success rate with them. They are over 99% effective.
1191357
These were incredible when I first got them. I used them as replacements on my MEE headphones. I wanted to block out the sound of others in my office and they did a great job at it... for about a month. After that, I noticed the tips were getting thinner and thinner every time I pulled them out of my ears. It was like the memory foam wasn't expanding back out. I also noticed the noise insulation slowly going away. I could start to hear my coworkers talking over my music. Finally, after about 5 months, chunks of foam started to fall off the tips and I had to throw them away.

I know there are multiple pairs in a pack, but I have multiple pairs of headphones so I don't have replacements for the ones that fell apart. I will be looking elsewhere for a new pair.
486327
Decent coasters, but the big problem comes with flat bottom glasses... which tend to form a suction grip the coasters after sweating. Which inevitably leads to the coasters sticking to the glass when it's picked up, and then the coaster drops to the floor, shattering if it hits anything but carpet.
3773879
Great quality coasters , lost a star because the holder for the coasters feels like it could break if not handled with care
3169076
These were awesome for a little while.  I bought them to add some extra awesome to a stage set up, but they have since been moved to the back of my computer monitors.  As of about a month or so ago, either the remote or the remote receiver stopped working.  Now, the only way I can power them off is by unplugging them and the multicolor selling point has degraded to simply blue since I can't change the color.