This is a tutorial about how it's possible to change your crosshair color to any rgb color in counter strike 1.6, 1.7, 1.8 (it is probably to work for any other versions as well).
Step 1. Go to your game directory/cstrike and open the file called config.cfg (or any other file that you use as main cfg) with notepad.
Step 2. Seach in the opened cfg file the line: cl_crosshair_color (if you can find it then you can add it, somewhere in the document).
Step 3. Select your color from
here, once you picked up your color from that tabel, look at red, green and blue (R G and B) values from the selected color. You can add the color to you document as follows:
cl_crosshair_color "63 10 152" //this is for purple.
To understand the RGB colors, the first value 63 -> is the value for the red color, the second value 10 -> is the value for green color, and the third value 152 -> is the color for blue color, all these colors combined together creates the purple color.
Note: If you change the color again, from the Main Menu of the game, you will need to modify the config file again, and to follow this tutorial along for the wanted color.
Good luck.