Thanks for your information and interest in stone ice cubes. There's some further information I would like to share with you regarding "stone ice cubes". Soapstone should be used and not marble or granite. They both have a level of porosity and different flavors have been known to stick with them for a while. Soapstone absorbs nothing and won't have any flavor after the cubes are washed. It naturally holds temperature a bit longer because of its density being more than either marble, or granite. Soapstone is also known for its ability to maintain temperature longer than marble or granite. The company I work for sell Soapstone Ice Cubes in 6-packs and 24-packs. They are made in Vermont USA and you can see them at: http://www.temperatureware.com/coolwa... - The last thing is that they actually work if there are basically 2:1 Cubes to liquid, thus the math does work out substantially better when you have twice as much frozen stone mass in relation to un-cooled liquid. Hope this helps!