This Certificate icon is made in Material Design style developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 4,300 icons, all in the same style and quality.
The icon Diploma 1 is a large vertical rectangle. Inside the rectangle, towards the top are two horizontal lines. At the bottom of the rectangle is a circle with a rectangle coming out the bottom, with the bottom being inverted like a triangle.