[PurpleKat]

I use a coaster that's marble, that my hamsters can lay or just stand on if she gets warm.
Sure you could use ceramic, and tiles could work too.
Also, small amounts of ice chips in water can make it more palatable, I change the water daily especially in the warm weather.
Ceramic hides are nice too, I use large candle holders, and my hamster loves to sit in a groom. Even found one in a charity shop big enough for my syrian (she's a big girl).
Ice bottles near the cage can help keep them cool where they sleep, no too cold its unoutable or unsafe.