The main "brand" colors are:

• #a4c639 Android green (pre-2018)
• #1a1a1a 90% gray

When used as an icon, the gray background is used with a green quill.
In other cases, the logo is used with a white background and green quill.

It consists of a quill (quill.svg) used as part of the letter 'Q' (Q_centered.svg). Currently, the height of the Q is 1.2 times it's width, however this may be subject to change.
The quill is integrated into the circle by applying a slight stroke to it, which can then be removed from the circle using a difference operation on both paths. This results in some slight negative space around the quill, making it more visible.

The complete Q must always fit into a circle with a diameter of 72px (assuming Android icon guidelines) as shown in adaptive_icon.svg.