Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Pretty looking optical illusion, mediocre coasters...

Oversight on my part...If you're going to get coasters to absorb liquids that sweat from your cups, pick something other than glass. Leather, wood, and cork would probably be far more suitable options.While these are pretty and very decorative, they're terrible at doing what they're designed to do, which is keep my table dry. Whenever I put a cold drink on one of these, there's soon water sweating off the glass, onto the coaster, and then pooling on it until it dribbles off onto the table.These coasters need a lip to prevent spillage and make them useful.To add a bit more disappointment, the clear rubber feet on each coaster are not put on uniformly, creating an odd staggered look into the optical illusion of having these coasters stacked.Again, very pretty, but not practical and not terribly useful.