How can I get my ice cubes to be perfectly clear. Aparently bottled and or purified water makes no difference, I load up the ice trays and they always come out a little white inside. Just curious what makes them that way, and any way to make them clear. Seems the small square ones in the restaurants are rather clear.
I think it has to do with the restaurants having that dimple in the middle, right where the white would be. Maybe it has to do with the water expanding just before it freezes? Or the outside freezing before the inside?
IIRC, they let the water that goes into icecubes sit for a while before they put it in so something happens that doesn’t cloud up the water. The oxygen dissolves out or something…
I’ll grab a couple ice-cube trays and get back to you. 
I was told–though I don’t know for sure–that if you boil the water first, the ice cubes would be clear. It supposedly has to do with dissolved oxygenand other gases) in the water.
This answer may be apocryphal.
If I fill my ice trays from the Pur filter on my kitchen faucet (it has a very small stream and the water isn’t agitated going into the trays), and then freeze the ice in a very cold freezer, they are clear.
Water purity and low dissolved gases are factors in growing clear ice, but by far the biggest determining factor is how the water is agitated or flows during the freezing. Boiling the water won’t do anything if it’s just thrown straight into the freezer in an ice cube tray - I know 'cause I tried it specifically after reading something about clear ice here a few months ago. Both the cold and hot water ice cubes were identical; cloudy. All you need to do is figure out how to gently stir the water or flow it over the forming ice while it’s freezing. This allows the bubbles to escape from through the surface as the water normaly freezes from top to bottom trapping bubles inside the cube. Read this page to learn more about making clear ice.