Metal coasters (and glass ones too) are all well and good, but if you put a glass with iced drinks in and they drip condensation, the water causes a vacuum under the glass and when you pick the glass up, the coaster comes with it and then suddenly comes crashing off, really a problem especially for unsuspecting guests. My coffee tables are those clear glass type and when you hear a coaster hit one of those from a foot up, is quite a shock. I've had guests break two glass coasters so have stopped using them.

I have tried metal (aluminium & stainless steel) and glass and they are all as bad as each other! Fine for hot drinks and tall wine glasses, but any iced drink that the condensation drips down onto the coaster causes this. The lighter the coaster the more likely it is to stick and drop off. They need to be really heavy to avoid that and my aluminium ones are the worst. If they have a rough texture on the top, that also stops this happening, but smooth glass, frosted glass, polishes aluminium, turned aluminium etc are not a good idea. I've resorted to using

I have these coasters from Stelton I think more then 10 years.