GSCol (Group Smiley Color) is a group power that allows you to change the default color of all of the smilies posted in your chat.
To change the default color, assign this power to your chat group and then hover over "group" at the top right of your chat and click "customize". Alternatively, you can use the direct edit group link. Once you've entered your chat password, visit the group powers tab and find Gscol. Enter a color code into the box, e.g. #ff0000. Then click "save" at the bottom of the page.
Note: This power is required for Gback to be used on a chat group.