The logo for Sigma pretty much looks like the letter E. The symbol has a deep bent in the middle towards the right and the middle ledge doesn't protrude as much as the top and bottom ledge.
This Sigma icon has Android KitKat style
. If you use the icons for Android apps, we recommend using our latest Material Icons icon pack (please check our sidebar on the right). Otherwise, it's a solid icon pack that looks good in small resolutions, either on the web or in print. It's characterized by thick lines, smooth corners, and is optimized for 24x24 pixels.