If your Colorimeter does not have a CAL button, use the instructions in the document below to calibrate your Colorimeter.

http://www2.vernier.com/til/1665/colorimeter_calibration.pdf

If you are using EasyData for data collection, Vernier can provide you with Experiment AppVars for the Colorimeter. Please contact Vernier if you are interested in obtaining this file.

Related TILs:
How do I calibrate a COL-DIN Colorimeter using the LabQuest App?
What model Colorimeter do I have?