@yangxin (View Post)

 Try to be a little more discriptive.

Anyway, from what i could make out from what you said:

To change the colour of diamond, go to decorations menu, choose a colour and paint with the mouse.

https://powdertoy.co.uk/Wiki/W/Laser_design.html

https://powdertoy.co.uk/Wiki/W/Hidden_manual_for_photons.html

everything about photons are in the above 2 links. Read through them and find out what you want.

Go to console  (~` key), or they C in the top right corner.  And type      "     !set type phot dmnd     "    No quotation marks.     Also,  https://powdertoy.co.uk/Wiki/W/Using_the_console.html for console commands.